What is Al Haouz and Haouz Of Marrakech
In a study of the social history of a region, one can wonder whether it is not futile to want to rigorously define the limits of it. First, because its borders are not those of a state court, nor of a nation, and that even though would be, what happens around can have as much, if not more important to explain what is happening on the stage itself. One could agree to study only the effects of history in a well-defined geographical area, but how to define this area in a univocal way for all?
In fact, every scientific discipline concerned with reporting to space its object of study gives a different definition to the notion of the region. The superposition of geological, geomorphological, ecological, botanical, agricultural, human, administrative, to name but a few examples, reveals more overlaps than overlays.
In the same discipline, moreover, the authors among them do not always agree, and they sometimes come to contradict each other in the same book.
It must be recognized that the concept of the geographical area still lacks sharpness and wraps series of considerations non-hierarchical. The vagueness of the concept cannot admit separately to different researchers, an acceptable synthesis, each discipline is entrenched in its own effort of rigor, and consequently diverges more and more of its neighbors instead of contributing to a global vision. If regional geography is meant to be a synthetic science, we will agree that it will be more of an art, as long as the hierarchy of variables taken into account to define the regional space.
The solution proposed by J. KLAZTMANN is certainly a progress sensitive towards systematization, but it supposes the uniform taking into account of the same variables; it is applicable only in a space where the discontinuity of the associations of variables is significant; that is to say, where an old history has allowed to gradually rebalance the too strong discontinuities of the environment, where the human investments managed to soften the too brutal disparities zonal and interregional. Then the mathematical method, the topological distribution. can reveal the nuances, where they have become difficult to detect, still showing the effect of variables related to the environment and history, not yet completely dominated by the only dictatorship of the cost of distribution.
It amounts to remember that the region is also a product of history. Where man is still weak and helpless before natural forces, the method of apprehending the region cannot be the same as where millions of hours of work are accumulated to the hectare, incorporated into the landscape, into the layout of the space in machinery and in industry.
In the Haouz of Marrakech, some attempts attempted distribution mathematics, on the advice of KLAZTMANN, learned nothing more about large ensembles, than what we already knew and who jumped at the eyes; but these large sets, already distinguished, covered in a single cloak of uniformity zones and sub-zones very apparent in the landscape. It has been possible to invoke the lack of precision of the basic data, the pre-statistical age of regional knowledge in Morocco. The disparity of the economic actors, but it seems especially, that a systematic application of the same variables is not heuristic so much the fragmentation of the space raises totally different considerations in irrigated for example, in the pumping zone or in Seguia zone, in plain or dir, etc.
No doubt, when the Haouz of Marrakech will have been entirely equipped with a modern irrigation network integrating the waters of all seven watersheds overlooking the plain, into a mercantile, where men, capital, materials, and energy will be fully mobile to be in a rational system of less In the places of the highest efficiency (production, profit, social satisfaction), mathematical models can account, more than the hesitant and intuitive appreciation, for the limits and structures of the Haouzian space.
But here we are between two ages! Physical geography not enough to explain the reality of the Landscape; economic statistics lack data and are largely powerless.
Finally, if we want to move away from the specific definitions of each discipline, the notion of a region refers today, consciously or not, to the idea of development, as it used to to the idea of administration (taxation, police). It is therefore resolutely placed in the historical context of voluntary geography that a regional space can be defined.
Having pushed as much as possible and in all senses this reflection, it appears, in fact, that we are dependent on two great sources of information of quite different nature, belonging to two different modes of approach of the regional problem: a historical, abundant and ancient source Bearing on the relations between the Makhzen and the tribes of a part, a recent administrative source, natural possibilities. It would be naïve to believe that one can easily avoid the preferential use of these treasures and that one cannot forget that other aspects, such as the distribution of consumption or indebtedness, escape us almost completely.
The definition of the region is also dependent on the nature of our information. As long as the hierarchy of variables has not been established and these quantified to be taken into account, and not taken into account because they are previously quantified, the region geographic will remain a pure contingency.
At the level of language, the word Haouz is enough to designate the plain between Atlas and Jbilet and Marrakech is the capital. But it should be noted that if the hawk par excellence is that of Marrakech, other cities are flanked by qualified spaces of the same term: including Fez, Meknes, and Rabat. Tangier, Tetuan. These are mostly Hadriya cities, that is, cities of the royal residence, intermittent state capitals, in which the first urban bourgeoisie around the Central Power developed.
Etymologically. There is in the root hza, yahäzu, the action to monopolize, to appropriate, to pursue oneself to the outside – hunting, to get rid of, to push back for better own one thing. The hiyäza is possession by long enjoyment, and the haüz is the possession characterized, the place surrounded by a hedge, or a wall, an enclosure.
Historically, it seems that the first mention of this term either in the work of the Arab geographer ARRAM as-SULAMIS, who uses more exactly the plural ahwäz in the sense of suburbs, surroundings regions surrounding a city. The plural would express a vision
Sectoral centrifugal, radio centric space; in front of each door of the city would open a sector, a region. The use of the plural suppose an inner perception of the city; the singular Haouz would designate, from afar, a global space, in the middle of which the city radiates.
Originally no precise limits so! Here a center, the finger Koutoubia rising, testifying to the unity of God, around which radiates, organizes and progresses the civilization of Islam, in a country of disbelievers and savages!
The Haouz is not only a suburb, a suburban halo, but it is also a safe zone opposed to the void threatening spaces area; it is concentric with the horm and repels the hlaa. The horm is the sacred prohibition, the hau: the secular space of peaceful enjoyment, the hlaa, the disturbing emptiness.
DEVERDUN informs us that “the description (from Marrakech) Masalik is curious but logical: it is a route according to the old method of Arab geographers. It starts from the palace, that is to say the essential, and, respecting the hierarchy, walks towards the great gate of the Kasbah. We go from the inside to the outside. The Haouz is just beyond it is what is gained on the void, on the negativity.
HAOUZ BEFORE THE WORD
We cannot imagine, Haouz before Marrakech. To consider the same space, it would be necessary to make a complete reversal of perspectives, to settle on the plateau of the Kik for example, and to seize the plain only as an extension of the mountain. The opposition then would be of the azgär in relation to the adrär, of the flat Country with respect to the pastures: ancient vision, certainly, which transpires among the geographers anterior to the foundation of the capital of the south, at the time when the itineraries passed by the small ones cities’ Ailen, Agmat, Nafis, Afifen – established at the outlets (foums) of the Main rivers.
Retrenched in the near mountain, the retreat protected by defiles, the Masmoudiens dominated the great depressions of the north where the Bagawata tribes circulated. Game steppes and winter pastures, these complementary spaces of the pastoral economy constituted dangerous zones, of temporary occupation.
To follow El Bekri along Dir, one jumps valleys “charming” of oasis of prosperity in cities and stages. But it does not tell us anything about intermediate spaces to go from one to another. Even silence under, Sigilmassa and other provinces, but omits Naffis and speaks of Aghmat only as a trade relay.
Marrakesh Tensift El Haouz in History
We find for the first time the term Haouz as toponym near Marrakesh Tensift El Haouz and in an indisputable way – on First-Hand documents and excluding a nominalist intent – in a letter from Yahya or TAFÜFT written to His Uncle Yahya ibn Abdallah and the inhabitants of Sernou a few days before March 28, 1514 “:” ya nahnu tarana bi-lhaüz Mahaddinin al-wad “which can be translated as: “and as for us, here we are at Haouz, encamped at the edge of the Wadi” – d ‘after the context it must be the Tensift Wadi.
Around the same time, Hassan EZ ZAYYÂTI, known as Léon the African, gives to the region of Marrakesh, precise limits, which define quite well what we call today the Haouz if one increases it of the mountainous basins:
It is clear that already for MARMOL, there are eight sectors around Marrakech, calling together Haouz and that one of them wears the same name as the set.
The names mentioned by MARMOL are not all identified, but we can easily find in hara the extra-muros district of the leprosy: it is worn on the old maps that we own in Marrakech, such as the WASHINGTON plan “‘But as Moulay Abdallah the Saadian (964-982 h/1543-1557 JC) moved the leprosarium Bab Aghmat, where she was since the Almohads under the name of herar al judamä, in Bab Doukkala where the said place is still known today, we cannot know if Marmol means by hara a sector south of the Haouz or a sector north Cortuben is certainly put for corridors” is the translation of debbâgin (tanners) whose door opens towards the Wadi Issil. Terguin is the name of an establishment on the banks of the Wadi Tensift, close to ford or bridge This is also the name of a small town near Mazagan, often cited in the middle of the 16th century in Portuguese documents:
By the end of the sixteenth century, the expression Haouz stands out as a synonym for the wider suburbs of Marrakech but continues to designate more precisely the immediate surroundings of the city without crossing to the east the Wadi Issil, limited to the north by the Tensift and including the irrigated right bank of Nfis. It is also what the first cartographers of the Protectorate will hear by Haouz, as can still be seen on the sheet Marrakech to 1/500,000 published in 1954.
Today, however, the Haouz is much bigger than that and is rather lexicographically related to the happy expression of Doutte: “the hoûz, that is to say, something like” Provence “,
Modern Inflation in Marrakesh Tensift El Haouz
The considerable increase of space named Haouz since the XVI century continued during the twentieth. Certainly, the tertib of the years 1915 and 1916 lists in a rubric named Haouz plantings totaling less than 5,000 hectares. It would have been like a restriction of the space Houzien a little before the protectorate.
A 1: 200,000 map, edited by the National Geographic Institute in 1920, calls Haouz the immediate south-west of the city of Marrakech; the letter covers about 10,000 ha of so-called “makhzen” land, partly “guich”.
The reissues in 1954 of the sheet Marrakech (map to 1,500,000) also published by the IGN, is widely spread north-west of Marrakech a Haouz of about 100,000 ha of area, ranging from west of Sidi Zouine to the east of Jbel Ramram, and crossing the Tensift obliquely.
In the Moroccan Monographic Atlas published in 1951, the plain of Haouz figures as the territory between the High Atlas and the Jbilete, the edge of the Tekna plateau to the west, and Tessaout to the east, with an area of about 435,000 ha.
To this already considerable extension of the meaning of the toponym had to add a new one, in 1961, with the creation of the “perimeter of haouz” of the National Office of the Irrigations: © perimeter which encompassed not only the plain of Haouz in the strict sense, but extended as far west as Chichaoua, and as far north as Umm er Rbia. Thus demarcated, the perimeter of Haouz was a very artificial creation, covering a little over 900,000 ha. This perimeter was then, in November 1966, administratively reduced to the plain directly irrigable by the contributions of the Atlas Wadis, from the Nfis in the west, to the Akhdar in the east. This vast territory covers some 350,000 ha. To which must be added the mountainous feeding ponds of these same Wadis (about 874,000 ha).
These verbal inflations are significant, on the one hand, the success of the word itself varies allegorical. Euphonic connoting the extension desire for the omnipotence of the state and secondly revealing the confusion of points of view.
The first rigorous attempt to define the limits of Haouz returns to Jean DRESCH, from observations on relief and geomorphology. For this author, the Haouz first is included between Jbiletus and Dir Atlas, in addition, if we can admit the existence of a big Haouz. It is advisable to distinguish Eastern Haouz from the rest, because “Tessaout and Lakhdar belong to different hydrographic basins” (pp.491, 524). As far as the separation between the western hawk and the central hawk is concerned the Position of John DRESCH is clear, it includes the Nfis in the western hawk (page 504)
A definition properly orographic, for purposes of the Haouz limits, would be the ones that would include the areas of the Nfis Wadi, Rheraya, Ourika, Zat and Rdat. Beyond, towards the east, one cannot really speak of Haouz but rather of the country Zemrane, or better of the basin of Tessaout; the Wadi Larh which acts as natural collator Tensift, in the same way, the limit to the north. In this sense Orographic, the low plateaus and hills of Tekna. Ourir and Oulad M’Taa, in the west, are rejected out of the Haouz. The ridge of the Ardouze north of Mzouda, and the intermittent bed of the Wadi el Bied, a tributary of the Tensift, end towards the NO of closing it.
It is to the south that the limitation of Haouz is more difficult to stop and especially on two points: the outlets of the valleys (forums) and the hills of Tamesloht.
As high as we go up, and almost up to 1500 m, the valleys atlases in the North Slope are flanked by micro-plots in terraces, irrigated by Seguias taken from the bed of the river. In addition, the irrigation of the plain of Marrakesh, and consequently its economic existence itself, is dependent on mountain watersheds.
Should we then understand, in the hydrological Haouz, the Mountain directly overlooking this plain? The correct assessment of the irrigation conditions of Haouz cannot, obviously, exclude the taking into account as a whole, watersheds that give in the plain, for the assessment of water supplies and their distribution in the time. But the study of the effective mobilization of this water and its distribution in space does not require to go back far beyond the outlet of the river in the plain.
Indeed, the most important aspect regarding the distribution of water in the plain, has so far been a guarantee of mastery water intakes in the river, that is to say, the maximum possible supply of the catch over the water. However, as will be seen, no plain Seguia harvest is located more than four kilometers upstream of the outlets. Thus the capture of the first lowland Seguia could limit the penetration of Haouz into the valleys, the Piedmont line connecting these extreme points.
From the point of view of social history, it is difficult to give Haouz precise limits, because there would be as many definitions of the Haouzian space as of periods cut in History. In the mountains, human groups have long since occupied districts of stable or relatively stable districts, as can be seen for the Seksawa, for example, or the Rifans, in the plain, on the contrary, and especially around them. a capital like Marrakech which has had a particularly rich history and many population transfers, the Haouzian space appears as a pulsating nebula, with vague limits constantly questioned. If one understands by Haouz the region directly dominated by the city of Marrakech and the central power, ie if one places oneself in the optics makhzénienne, then the Haouz understands the gardens of suburbs (Jnanat) augmented the domain of the state (Makhzen) and lands guich; it should be reduced to the current administrative circle of Marrakech-suburbs in French, and “Ahwaz Marrâkuch” in Arabic. The Rehamna and Mesfioua located in the plains east of Oued Issil would be excluded.
A breakdown from so-called ‘tribal’ denominations would provide another image of Haouz, well limited to the east by the river Tirhezrit- the Zemrane making without context not part of Haouz – but difficult to stop elsewhere: the Masfiwa occupy an entire sector montapu and go down to the middle of the plain in the area of R’dat the Rehamna span the Tensift, surround Marrakech au, and their movement area goes up to the Oum er Rbia: the tribes of the NW (Oulad Dlim, Doublal, Herbil), if they are in majority ie on the right bank of the Tensift, nevertheless have azib-s and pardans in the low sector of N’fis; it would be difficult, then, too, to decide. In the west, on the other hand, the traditional border between Marrakech and the Zerarate – formerly guich also – under Safi province, is superimposed perfectly on the limits of the irrigation zones. Similarly, the southern and southwestern boundaries of the irrigation areas of the orographic areas and the “tribal” boundaries are superimposed.
Three difficulties therefore to the reconciliation of “ethnic” cutting and hydraulic cutting: embedded complexity, truly tribal Rehamna, solidarities between the Masfiwa of the plain and those of the mountain, the mosaic of northern guich.
The evolution of political life and administrative geography in some way resolved these problems by creating, in 1958, the communes.rurales. We will have the opportunity to come back to the significance of the aims of the state in the creation of rural communities, as well as the attempt to end the idea of tribe. What matters to us here is that the new division of the fixed space, with relative precision, a territorial base simple and usable for any statistical and economic comparison. Nearly today, we can define an administrative hauz, the sum of a whole number of rural communes – twelve in total – whose new names only very vaguely return to the past: Ras El Ain, Ait Ourir, Oulad Ahsoune, Abdallah Rhiate, Rhmat, Tnine Ourika, Tahanaout, Tamesloht, Saâda, Jnanat, Tnine Oudaya, Sebt Aït Immour.
This division exists today only on 1/50,000 maps, but the number and name of the villages contained in each rural commune are known, and in each village, it is possible, in the field, to recognize the line which separates it from the neighboring village, even when the land changes, still rare in the extremities of the Haouz, are superimposed finagles and soils. This is obviously a considerable advance from the point of view of the administrative knowledge of space, which does not mean that it is one from the point of view of sociological knowledge. In the past, groups could be known by their centers, their subgroups, their splits, their leaders, but it was not clear where their territories ended; today it is the opposite, we get to know the space faster than the people who live there, so systematic is the refusal of the state to recognize spontaneous organizations.
It may be asked, if the new territorial division into rural mans, will survive the future water development of Haouz in the next twenty years and if the delimitation recognized here will be relevant with another distribution of water. This is a matter of concern to the caretakers, and some of the proposed “rectifications” have been postponed until the actual distribution of the water itself. The current division is, therefore, an administrative image of waiting for transition, which has the excessive ambition to create stronger solidarities between members of the same rural municipality than between old contributors, by the administrative practice, by the activity of a commercial, financial and economic center. The introduction of modern irrigation will affect the alignment of crops and pigeonholes, and discipline the whole of productive behavior, bringing farmers suddenly into a subsistence-rich subsistence economy, to almost entirely dependent farmers of the market.
It will not go without some changes, the solidarities of towers of water, lockers, and basins, connected to the canal replacing the ancient ethnic denominations. Will not this also be the end of classical ethnography?
THE NATURAL FRAMEWORK
To see the whole Haouz, you have to settle on the Kik. It also dominates the Tizerag ledge, which borders the Oukaïmeden plateau to the north, or the ridge that borders the plateau of Yagour, two high places of cattle pastors’; but from these two points of view too high, the relief of the plain is crushed, and rarely the air pure enough, in the lowlands, to allow to distinguish the details.
We arrive at the Kik by a nasty track coming from the valley of the Rhirhaya, borrowed by ju pilgrims visiting Moulay Brahim, or better still, by a path that climbs from the valley of Nfis to Aguergour, through an olive grove and green gardens cascading in travertine.
Threatening barrier seen from the plain, the Kik is like an advanced sentinel of the Deren on the banks of the Nfis, a little like the Tasghimut is in the basin of the Zat. It stands, immense, all oval, synclinal perched, and limestone table flanked by walls whose two doors are Aguergour on the side of the sword, and Moulay Brahim on the side of religion to the east, of course.
“Even so,” cried the Imam, “would there be a Kik on the Kik, and seven Kik superimposed, nothing would prevent the arrival of Thursday. It is also said in the Haouz, that one wishes the death of “those of the Kik” so that the area carries beautiful harvests: one explains this saying by a supposed opposition, between the climate of Kîk and that of Haouz; but no doubt the adage refers more to the geography of plunder than to that of rainfall.
Here we can see the legendary and probably historical danger, which represents for the plain, the dark forces massed on or behind the Kik, this Masmouda balcony overlooking the azarhar.
- FIRST OVERVIEW
Sitting on the cornice of the Kik, let’s imagine what could to be the landscape that extends to our feet, before the development of the first cities: Nafis, Aghmät.
To achieve this, we can use: the natural land pattern, which probably has a little variation on this scale, floristic studies, advanced knowledge available today on the circulation of water and climate data.
Beyond the foreground, very rugged terrain of the primary mass of
Sektana, the gaze plunges into the plain and, towards the horizon, barely stopped by the wrinkles of the Jbilets, spins, if the weather is clear, to the distant horizon to the north, closed by the Jbel al Akhdar on the left, and the Skhour (Rehamna’s Appalachian ridges) in front and on the right. Towards the west, one can distinguish only the reliefless landscape of the Ferjanes, beyond the primary snags of Ardouz de Mzoudia, hills that are said to “contain fabulous treasures or a gold deposit”.
To the east, the view is quickly closed by the isthmus of Tirhezrit, at the level of which the suspended basin of Tasghimout approaches, to the north of the Jbilets (Jorf of Ras el-Ma) where the Tensift seems to take its source.
By fixing the plain a little better, we gradually see reliefs, wrinkles, lines, shadows and, very quickly, it appears as much less flat as it seemed at first. On the contrary, in the early morning, or in the evening a little before sunset, the grazing lights bring out a tangle of ridges, a flight of slopes, a succession of cones cut by the Wadis that will all flatten and to confuse in the oulja of the Tensift locally called by the plural “Ouidane”.
It is first the Tensift which regulates, from below, the relief of Haouz: it is the basic level of all the hydrographic system of the true Haouz; it is its northern limit, in contact with the primary glacis of the southern slopes of the Jbilets. Transects, highlighting the slope of the terrain on both sides of the Tensift at different points of its course allow to better specify what already appears to the naked eye. For example, at the level of Sidi Zouine, following the line of greater slope represented by Seheb El Aouina, the slope is on the side of Haouz of 13%. it is 27% on the Jbilete glacis on the bank of El Aamir Wadi. Everywhere the slopes in the Haouz remain strong in the sense of hydraulicians and developers in the south-north direction, the weakest being at the site of the ruins of the old Zaouia Cherradia with a slope of 10%. In the east-west direction, however. on the alluvial terrace of the Tensift, the measured slopes are much lower and the flow of water is much slower than elsewhere: in places it stagnates clearly. Gradually, the individuality of each hydrographic system appears.
To the west, the Nfis deeply cuts the Olémo-Miocène massif of Guemassa bordered on its banks, by two long green ribbons occupying the low terraces, then opens into the plain slightly encased in a cone of slight curvature. In the middle of his race. in the plain between its outlet and its confluence, the Nfis bends sharply towards the north-west, while its superior course was south-north: it is then less concealed and flows almost on the surface of the plain which does not present there less convexity, but rather a regular glaze. After some large meanders between the Zaouia of Sidi Zouine and the ruins of Zaouia El Cherradi, the Nfis recounts again to reach its confluence with the Tensift and, on this route, it also plays the role of drain for the water table. Between the outlet and the confluence. The Nfis bed follows neither the strongest slope of the natural terrain nor the most direct line; he describes a broad concave curve towards the southwest, leaving on his left bank, a clear gutter that he had to take before, as several observers have already noted. New observations confirm these hitherto purely topographical predictions. The studies carried out for the study of the water table clearly show the existence of a more straightforward Nfis palaeochenal between the outlet and the confluence than the current layout of the bed. In particular, the 1/100,000 maps of isopiezzometric curves, iso-conductivity, and transmissivities, show a privileged flow of the aquifer along the old fossil bed. Everything happens as if, held by the two ends of its lower course, the Nfis had abruptly on the geological scale gets ripped in its middle towards the east, to make the curvature that its course presents today. Indeed, the maps expressing the different variables of the water table reveal clear anomalies and not graduated passages. Is this Nfis transfer during the quaternary contemporaneous with the tectonic accidents revealed by the Azofid fault?
Or the circulation on the different generators of the cone is-she that the result of the clean discharge of the Wadi during the slow uplift of the Atlas and the game of the fault: thus raising his bed, he would have constantly found next, a line of steeper slope?
The course of Rhirhaïa presents a completely different landscape. But, before describing it, it is necessary to stop for a moment on the name of this stream. As we said earlier, toponymy is congested in Haouz by trilingualism: the Araboberberian bilingualism that is the rule in the region, and the transcription in French characters, often fanciful, cartographers. When added to this the variations generated by a very long geographical object, like a watercourse, which crosses the territory of several human groups, we do not know exactly what santon to dedicate! And these are sanctuaries here. Upstream of Moulay Brahim, the river is called Asif n’Irhirhaïne, ie the river Rhirhaïa tribe currently on its shores which is given for descendant, onomastic at least, of Hargha, ‘predecessor’ of the Almohades ”. At the level of Tahanaout, the cards bear “oued Rhirhaïa”, or “Rhiraïa”, which is basically an Arabization more or less well noted. But from Sidi Chafi ‘, at Arhouatim where the course bends sharply towards the northwest, all residents call it the name of Oued Ba’ja, and the maps bear the toponym: “Ba’ja Jdid “, which would suggest that there is a Ba’ja Qdîm. Not to be found around Tamesloht, it is necessary to cross the hills of El Mûsiha “and the coast of Azofid, to discover that the Baja is divided into two pras: the one called Oued Qdim, which goes to the northwest and disappears in a flow in a sheet at the douar Mnabha: the other says Oued Ba’ja Jdid, slightly concealed, which flows northward and also ends, but much farther, in a sheet flow.
This is not just a problem of pure onomastic rule in the Haouz, and refers to the division of major ethnic and linguistic groups, and that we will have the opportunity to remember both Oued Ourika and Oued Zat but also a question of orography and hydrography, rather peculiar and still poorly understood, despite recent work.
The map of transmissivities confirms the indications of toponymy, and suggests that a first paleo-channel of Rhirhaïa-Baja was a little further west than today and borrowed the sketched arm by the Wadi el Qdim, to jump into the Tensift at the level of the douar el Guern. The Ba’ja would have rushed eastward like the Nfis Between Nfis and Rhirhaïa, a slightly concave flat surface, the Vette de Tamesloht deserves our attention, between the edge of the Oumnast hills and the Azofid coast. We now know what had already sensed Jean DRESCH “, and that the geophysical studies have confirmed, that a fault made play the primary block deep hills of Guemassa and consitué a horst, covered by materials conglomerates oligo miocene, some snags point (Musiha). One may also wonder if the north-south fault, looking west downstream of Tadert’s elbow, is not responsible for the flight of Rhirhaïa to the west, and this well before the choice of the paleo channel of Ba’ja Qdîm cited above. At the end of the episode villa franchien, the Haouz would have ceased to be a sort of endoreic basin “, as is still the Bahira today and the Tensift would then have served as an outlet and trained to the west all the Wadis (Rhirhaïa, Issil, Ourika, Zat) which contributed to the filling of the central Haouz.
The important thing here is the role played by Rhirhaïa in the delivery of water to the surface of Haouz. Except for exceptional flood, most of its inputs feed, on the surface or infiltration, on the one hand the synclinal basin of Tamesloht, and especially, on its left bank, the sector of Arhouatim in continuation of its superior course. Under normal conditions, flows of Rhirhaïa-Baja beyond Azofid are nil or insignificant, and occur very little in the Nfis water distribution system.
The cone that the Rhirhaïa leaves on the right and downstream, will connect laterally to the cone of the Wadi Ourika. The overlapping trace of these two cones is the trough of Oued Issil, which has not built a cone itself, having only a small watershed and playing only the sometimes violent role of a runoff evacuator. Tablecloths, following heavy rains of spring on the Haouz. Add that Oued Issil is the natural sewer of the eastern part of the old city of Marrakech.
Like the Rhirhaïa, the Wadi Ourika ‘changes its name in the different sections of its path, according to the human groups established on its shores.
Tody called oued (and not asif) Ourika, de Setti Fadma until the outlet in the plain, it takes the name of Wadi Ghmat from the coast 800 m around which a tribal no man’s land, between Ourika and Mesfioua, interrupts olivettes and cultures on a strip of 1200 m width, marked with cairns. Then it divides into two arms: the eastern arm borrowed by the diffluences of floods, and the western arm, that of the average regime and of low water. At its confluence with the Zat, the river enters the Rehamna country, on the left bank at least: the meeting of the Zat and Wadi Ghmat then takes the name of Oued Lahjar to its junction with the Wadi Tensift.
On the left bank, the cone of the Ourika seems very regular, unfolding largely its curvature until the contact of Wadi Issil. The minor bed, noticeably steeped in staggered terraces visible even from a distance, gradually catches up the natural terrain at the confluence with the Zat. It is only a little before the road from Marrakech to Tadla, that, again, it sinks into the low terraces of Tensift and plays the role of a natural drain of the water table riparian.
The flood diffluence drifting in the eastern arm the supplement “Water and that fails to use the usual channel, seems to result from a lateral shift on the surface of the cone, along with another generator, as is the case for the Zat for example. This bed, for the evacuation of a slice of higher flow, does not involve, strictly speaking, the threshold in its opening; it is only more congested in large parts left by the previous floods. Measurements made, his profile in length is, with errors of scale, identical to that of the main arm; It seems that they both have the same underflow. Nor does it appear to be the result of capture, although its downstream section, turning sharply to the northwest to join the first arm, in line with the bed of a right tributary, the Asif n’Qejji, much more active.
The right bank of Wadi Ourika presents the same system of rasses than the left bank, but narrower, and narrower, due to the presence of the foothills of the Tasrhimout basin (Jbel Sahl and Adrar bou Assaba) and forms the very characteristic landscape of the hajeb (ridges), terraced edges on which, very early, settled the man, and which today bear the densest villages and Olivette. It is set back from the Jbel Sahl, on the perched table of Tasrhimout, that is Agmat-Aïlan of the ancients, the acropolis of the pre-Almoravid Aghmat, and the former door of Haouz for which came from Tafilalet by Tizi n ‘Glawa.
The asymmetry of the Ourika cone is certainly responsible, in part, the success of agricultural development by irrigation around Aghmat, from protohistoric times. Indeed, for a volume withdrawn roughly comparable to that of the Nfis, the areas offered for irrigation on the Ourika cone do not cover two-thirds of the area of those dominated by the Nfis. The area of the left bank is ten times that of the right bank. Other physical and then human consequences can be mentioned below, but we can already understand why the water table on the right bank of the Ourika is better supplied and shallower than anywhere else in the cones.
The Zat cone is a geometric model of the genre. In the Haouz, the Ourika is known for its terraces, and the Zat for its cone: perfect volume of revolution with a steep and regular slope (more than 12% in the first twelve kilometers downstream of the outlet).
The bed of the Wadi is very little encased, the water flows almost on the surface of the cone and the formation of the terraces is hardly visible there. The course of the river wanders dangerously during floods, changing generators, or flowing in lateral layers, especially on the right bank, where the Wadi seems to find an old bed. Multiple channels, still poorly fixed today, despite the efforts of the hydraulicians, are formed throughout the course, and from the first five kilometers after the outlet. Currently, the Zat actually has three beds: a low water bed, the deepest and closest to the Ourika, so in the west, a bed of annual floods, through which the slices of water are discharged greater than about two meters and which joins the Hjar three kilometers downstream of the confluence of its first arm, by a long lateral discharge of two kilometers, a third exceptional flood flow which leaves the crest in its middle, in the no man’s land between the Mesfioua and the Rehamna, and seeks to make its way to the Tensift, along the Lauian Seguia, which seems to be using its underflow and perhaps an old channel whose banks are seen strongly two kilometers east of Zaouia b. Sasi.
The discussion on the hesitation (at the quaternary scale) of the Zat Wadi to choose a channel, was recently enriched by the publication of the ‘1/100,000 map of transmissivities (DRE, December 1972) bringing together the direct studies by means of pumping, and the results obtained on the Haouz Hydraulic Analog Model. This map shows very strong discontinuities in transmissivity, aligned along the course of the current Tirhezrit Wadi (natural collation, lateral connection line of the Zat cone and the Rdat cone). The hydrogeologists who are the authors of this map – Guy BERNERT and Jean Pierre PROST (November 1972) – evoke the existence of a paleochenal from the Wadi Zat, which has deposited there very important sediments of great permeability. The existence of a topographic exit from the watershed of Oued Zat, 10 kilometers east of Imi n’Zat, before the last quaternary uplifts, does not seem impossible to geologists.
If we have to admit these conclusions, the Zat cone is very recent, and this explains why the absence of the terraces 3 – 4 – 5 in the Zat is due, not to their ablation, but rather to the fact that, very weak, they were backfilled by the sudden and powerful appearance of the Zat in this place, in the last few episodes.
The Ourika – Zat system constitutes in the middle of the plain a hair of wandering channels, extremely complex and difficult to dominate. It is one of the marginal areas of human occupation in the Haouz, and for a long time, a much-contested border point between the Mesfioua and the Rehamna. In the past, it used shrubs and poplar groves, adjacent to the Rhouiba (small forest) and jujube trees whose namesake has been preserved, even today, near the shrine of Sidi Chafi ‘(x = 275,250 y = 119). It was, it is said, a haunt of brigands and highwaymen on the road to Sidi Rahal and Tafilalet.
After the thalweg of Tirhezrit we enter Zemrane country and we leave the Haouz. The cone of Rdat, moreover, is not visible from Kiîk and on the horizon, the advance of Tasrhimout merges with Jbilète.
This first topographic and orographic overview of Haouz, we already show a clear personality of the different cones. And what is clearly established in the mind, after a superficial but attentive examination of the Haouwz’s geography, is the strong diversity of very compartmentalized space. Ultimately, this is a very different point of view from that which a traveler arriving from the northern route, at the threshold of Jbilète, would have, and who would conclude too quickly that the flatness and uniformity of the plain.
To sum up distinguish: to the west, the cone of Nfis, flat, dominated
by the small bowl of Tamesloht; in the center, a wide undulation in which the cones of the Rhirhaïa and the right bank of the Ourika are buried; to the east, the very steep and regular Zat cone; Basically, against the Jbilets, Ouidane or side terraces of the Tensift which drains towards the west the whole system.
SUBSIDENCE AND OCCASION
The Haouz of geologists is a structural depression, in which accumulated continental Neogene sediments and quaternary of Atlas origin. But the individualization of Haouz only occurred very gradually, as the tectonic movements caused the chain of the High Atlas to emerge from the Eugene in the ancient Quaternary. The structural depression, initiating the erosion and consequently causing the beginning of its filling, was slowly and moderately subsistent, since its entheogenic background was not completely covered by the posterior sediments and emerges in the form of the small one’s hills of Musiha, Gueliz, Tazakourt, Koudiat el Abid. etc … constituted by straightened primary layers dominated by waterproof shales. Above, on the periphery, from east to west, and on the edge of the Atlas, unconformably, appear secondary and Eocene terrains whose upper layers are rather clayey and marly. It is the whole of this more or less concordant stratification from primary to Eocene which was folded into a vast half gutter supported to the north on the primary line of Jbilète, and in which the sediments of neogenic and quaternary erosion have settled.
The neogenic formations (oligomiocene, Pontian, Continental Pliocene. According to the places and according to the authors) cover a deep differentiated relief shaped in the rocks of the substrate, on surfaces which played until recently (fault of Azofid. Fault north-south of Gueliz) and who may still be playing (the seismicity measured at the Lalla Takerkoust dam classifies this zone among the medium-strong category). As a result of the variations in the altitude of the substrate, the thickness and the nature of the filling by the destructive materials are variable: conglomerates at the foot of the Atlas, the neogenic materials are finer and more loaded with clay in the middle of the plain.
Above this basic fill. The establishment of quaternary deposits has been dominated by the recent uplift of the Atlas and by the alternation of the quaternary climatic periods. The longitudinal profile of the alluvial transport system seems to have been less influenced by climatic periods only by the continuation of the differential (relative) subsidence of the plain. For example, the game of Azofid’s size seems to have had more effect than that of the Gueliz fault; the uplift at the Imi n’zat level is stronger than at the level of Agadir Tacheraft. Certainly, climatic variations, poorly known my pebbles in the surveys made at the level of the cones), and phases less active depositing finer sediments in the plain.
The final filling constitutes at the foot of the Atlas of deposits in stepped alluvial cones or nested, depending on the variations in the duration and intensity of the erosive episodes. Towards the north and the bottom of the plain, the cones tend to merge or to pass laterally to vast alluvial terraces. In a general way, these quaternary contributions are constituted in depth of conglomerates or beds of rollers more or less compacted by clays, while on the surface are spread of silts or even alluvial sands, which participate in the formation of the soils of Haouz. Neogenic and quaternary deposits are the only ones that contain significant water tables.
The Atlas Wadis which open into the Haouz and which are responsible for its filling, all belong to the Tensift hydrographic system which is only their natural collation and the evacuator towards the ocean of the surplus of the contributions having streamed or drilled through the plain. Each Wadi in the mountains comes from a watershed independent, by definition, even if it mixes its deliveries in the plain with another flowing Wadi.
The liquid and solid products poured into the plain, are narrowly determined by the climatic regime and by the characteristics of watersheds (total areas by altitude sections, litho-logy. plant cover etc.
If the global climate regime is fairly well known for the small regions covered by the watersheds of Wadis, on the other hand, thinner mailes, by watershed rain information is too scarce. Too mismatched series values too questionable, to be validly retained. The best can we store the average rainfall at altitude? We know quite well what flows to the outlet of the Wadi approximately the surfaces and the altitudes of the watersheds: one can know the surfaces of the different lithological outcrops and estimate by runoff coefficients. The flow of atmospheric water.
These data are summarized in the following table:
|Oueds||L (km)||S (km²)||Zm (m)||ZM (m)||P %||Pm (mm)|
In this table, L represents the length of the Wadi in the mountains in km, S the area of the catchment area in km, Zm the altitude in m of the horizontal line which divides the catchment into two equal halves, ZM the maximum altitude of the catchment, P% the slope average of the accumulation basin, Pm the average rainfall. The Wadis whose names are underlined are those whose debits are regularly measured for at least thirty years by the technical services of Hydraulics and Agriculture. For the others, those who have never been the subject of observations average annual contributions were evaluated from neighboring Wadis by interpolation.
The lithological composition of the feeding basins presents a practical interest, because the importance of the solid flows of the Wadis, therefore the construction of the cones, is directly linked to the presence of erodible rocks of the watersheds, factors which closely condition the siltation of the Seguias catches downstream and the filling of the dams, i.e. Their lifespan. In this regard, the main basins can be classified as follows:
|basins||outcrop of loose rock as a% of total area|
This classification is only a very general indication because it groups in the “erodible” category the continental and lagoon red formations as different as those of the Jurassic or Triassic Cretaceous.
Pour ne tenir compte que du trias, formation plus facilement éro-dable, on obtient des valeurs un peu différentes.
|basins||% Triassic area|
Generally speaking, outcrops of loose rock are therefore more developed in the east than in the west. Part of the explanation for the relative youth and steep slopes of the Ourika and Zat cones lies in the load of the flows of solid products from these Wadis.
|Cones slope||Side at the bottom meters
|Side at Tensift meters
|Difference in meters
|Distance in meters
Source: Map at 1/5,000 °
On the other hand, the importance of permeable rocks susceptible to store water, conditions the regularity of the hydraulic regime. Examination of the lithological map shows that the permeable formations, corresponding to limestone rocks (Eocene, Cretaceous, Jurassic, even primary), are poorly represented.
|Total area in km²||1703||324||574||496|
|marl and clay||15,4||14,6||23,5||43,1|
Sources: – Structural sketch of the Grand Atlas at 1/200,000 ° by J. DRESCH, Rabat 1938 – Geological map of Morocco at 1/500,000, Rabat 1955-1956.
– Map only where qe watersheds at 1/200,000 ° by
- COCHET, 1962.
– Map of watersheds on the IGN topographic map at 1/200,000 °.
a – The Wadis regime
The flow rates of the Wadis of Haouz are better and better known but they have only been subject to observations since recent dates and with various methods which are difficult to connect to each other. In addition interruptions and lack of fidelity in the measurements, both from a theoretical and practical point of view, greatly disturbed the data.
Nfis has been studied since 1924, Rhirhaïa since 1927, Ourika 1928, Zat 1931. The gauges carried out by the surface velocity method, lack precision and this has long been the only method used. More precise measurements with the reel have been made since June 1962. In 1970 the different measurement methods were rigorously compared, so as to fix coefficients to be able to take into account all the data. All of these were taken up on a computer in order to be able to feed a mathematical model of hydraulic circulation which we will talk about later. So that we know better and better the liquid contributions of the Wadis of Haouz. We can summarize the progress and variations of our knowledge in the following table:
Average annual flows of Wadis in Haouz from Marrakech
We note that the Wadis Nfis, Ourika and Zat, each increased by its tributaries, bring about the same flows in the plain, we will see later that they are far from dominating the same areas and that, consequently, the irrigation possibilities offered by each of them are very different.
Variability of flow rates
The total volume delivered to the outlet, expressed in millions of m or transformed into a constant fictitious instantaneous flow, conceals large seasonal variations annual and interannual. which, in the absence of a significant accumulation dam, directly affects the irrigation conditions.
The seasonal variation in flow rates is very marked. For all the Wadis, the low water level occurs in August, then the flows progress slowly from September to February to reach their maximum from March to May, with a maximum “sharp” in April.
|Wadis||average inflows millions of m²||Coefficient of variation|
Generally, the seasonal flows of the Wadis follow, with a certain time lag, the precipitation.
In autumn, the grounds are dry and have a strong retention power, evaporation and evapotranspiration of the plant cover are strong. As a result, a significant part of the precipitation is retained in the soil and stored in the subsoil: especially in the Zat watershed where the proportion of limestone outcrops is greater (11.4% of the total surface), much less in the Nfis where it is lower (5.2%).
Winter and early spring precipitation is immobilized in the form of snow in the high mountains. The April and May precipitation flowing over land already saturated with water and adding to the snowmelt, swell the flows of the Wadis: the spring floods are, therefore, often much more spectacular than those of ‘autumn.
Floods, which reveal instantaneous variability, or of short duration, are also extremely variable from one year to another and affect the hydraulic water distribution system itself (dams, intakes, Seguias) to the point of l ” damage and put it out of service during the period sometimes decisive for cultivation. Instantaneous flows can, for example, vary in the Nfis from 2 m³s to 860 m³s.
Analysis of hydroeram and direct observations show that when a downpour affects the entire catchment area, the flood is always characterized by an acute “peak”, a short rise time and a very rapid decline. This pointed form of the flood results from the topography and morphology of the basin: stiffness of the slopes, low rate of afforestation absence of flood field upstream.
The annual variability also very strongly conditions the conditions of use of water for irrigation purposes, and above all, the cost, the profitability of the dams, that is to say, ultimately, their very existence. To highlight this variability, it is convenient to use the Galton-Gibrat lines plotted on gausso-logarithmic graphs which we will spare the reader so as not to overload this book, but whose figures are the results below.
The variability of the flows over short, (seasonal) or long (interannual) periods affect the natural conditions offered to irrigation: possibilities of perennial crops reduced to low inputs of low water (except contributions of the groundwater), irregularities of resources in water from one year to the next, which results in large variations in the cultivated areas and in agricultural yields.
b- Solid flows
Solid flows could be evaluated from direct measurements made on samples taken regularly during the different flow regimes of the Wadis and on an estimate of the backfilling of the Lalla Takerkoust dam since its construction (1919-1935). The information gathered gives, roughly, the following figures:
|Wadis||Solid flows in kg/m3||Annual volume in m3|
While being well aware of the danger of handling large figures, let us note, by way of illustration, that such solid flows are capable of constituting masses of materials of volume equivalent to that of the cones built downstream of the outlets of large Wadis in a million years for the Nfis and the Ourika, and in two hundred thousand years for the Zat – all other things settled – that is to say, assuming constant: the climate, the hydraulicity , forest cover of watersheds, etc.
The solid flow mainly comes from erodible formations. Taking into account the corresponding areas by basin, the following specific degradations are obtained on the watersheds
V = Annual volume of solid flows transited (thousands m3/year). S = Watershed area (km²)
D = Watershed degradation (m3/km²/year)
Pm = Average rainfall (mm)
P% = Average slope of the watershed (%)
RM = Percentage of the catchment area in outcrop of loose rock (%).
The specific degradation of watersheds is directly related to the amount of precipitation and the average slope of the watershed.
Groundwater Marrakesh Tensift El Haouz
In addition to surface water which more or less capriciously feeds gravity irrigation, the water table plays a remarkable role in the Marrakesh Tensift El Haouz. Very early in history, the originality of the water extraction system by Khettara encouraged hydraulic engineers to reflect on the mechanism of the supply of the water table and on the underground circulation of water. If the rigorous knowledge of the flow of groundwater really started twenty years ago with the first studies of AMBROGGI and THUILLE \ and continued thanks to the work of COCHET, it was from 1968, really, that a remarkable leap could be obtained by BERNERT and PROST 3 to which was entrusted the synthesis of all the information collected since 1927, both for surface water and for groundwater.
The objective being to succeed in drawing up a dynamic balance sheet of water circulation on the whole of Haoüz, the powerful means of calculation and the making of an analogical model necessary, exceeded the possibilities of isolated researchers, and could not be carried out than in a large-scale administrative framework, involving separate departments such as Public Works, the Department of Mines and the Office du Haouz.
The study of the water table consisted of a computer retrieval of all the information (several hundreds of thousands of data) collected since the first surveys, after having made the information obtained with different methods compatible with each other. Transferring this information to a formal model, grouping it according to their location in space, in relation to a grid of two-kilometer coordinates (computer capacity limits), made it possible to constitute an analog model. This model currently exists in three forms:
Ñ a coarse model, cut out by basin, in the conductive paper, where the circulation of water is represented by the transmissibility of an electric current, and on which it is possible to instantly display a hundred potentials and fifty separate intensities, using potentiometers, and measuring their effects with a simple galvanometer;
– A more sophisticated electronic model, positioning, by grouping, the transmissivities of each two-kilometer mesh of the whole Haouz, and on which the overall simulations can be made;
– Finally a mathematical model, which provides for the 2400 knots cut in the Haouz, the instant hydrodynamic balance. The simulations are indeed more representative than the information provided by the maps drawn from point data as numerous as they are.
The results of all this work have not yet been published, and if the adjustment and compatibility tests of the model to the real have been completed and considered to be valid, the prospective and historical simulation tests are in progress. However, we can remove, from the enormous encrypted directories produced by the computer, some significant hydrodynamic facts to understand the circulation of water in the Haouz plain.
a – The groundwater supply
The Haouz aquifer is supplied with water from three different sources: Atlas water, precipitation on the plain, re-infiltration of water which is withdrawn for irrigation.
The precipitation which occurs on the mountain ranges, roughly estimated at 50 continuous fictitious m3/s, flows through the Wadis and along the dir. Along the Wadis bed, infiltrations are not important because they have a linear appearance, but the Wadis waters are diverted by 150 km of Seguia, distributed by 5,000 km of distributors (rnesref) and spread in sheets in the fields (calants and ridges) over an area of 150,000 ha. These artificial infiltrations, but carried out without human intention, which occur along the distribution network and in the irrigation fields, are a little more than 5 m3/s fc.
Along the dir, infiltration due to runoff in sheets (jaid) is significant, especially on the left bank of the Nfis (940 Is/fc). Indeed, the small watershed of 80 km2, which constitute the hills of Tiourar in relatively impermeable materials, pours all the water that it receives, increased by flows flowing from the glacis of Amizmiz in the particularly deep and permeable pit located at the foot of the Azofid fault.
The permeability of the dejection cones has been studied directly by drilling by hydrogeologists. The tests showed difficulties in overfilling the water table by drilling, but they also showed that, over large areas, infiltration can be very significant. Infiltration rates of the order of 20 l/s were obtained by drilling, especially in the upper 20 meters of the formation of debris cones. We were able to calculate infiltrations of the order of 20 m3 per km2.
The groundwater is also fed by precipitation which directly affects the plain. The flow in the aridity conditions of the Haouz is almost zero. Except for quite exceptional rains, the ground is never saturated.
The flow therefore depends mainly on the more or less skeletal nature of the soil. However, it should be noted that, whatever the evapotranspiration formula is chosen, the rain is always less, on average, than the potential evapotranspiration. To have a flow, one of the following two conditions must be fulfilled:
– Either rain or a sequence of rains sufficiently abundant to exceed the soil’s retention capacity. As soon as this capacity is satisfied, the rain fills the saturation margin, a little evaporation occurs during drying. If the saturation margin is not reached, unless hydromorphic conditions such that water cannot descend, the water stored in the margin will percolate and will be found in the groundwater. If the saturation margin is exceeded, there will, on the contrary, be surface flow. This type of flow, therefore, depends: on the retention capacity of the soils and their saturation capacity, on the rain, and on the previous humidity state.
The retention and saturation capacities are determined by the volume of soil. Each layer that makes up the soil column has its own capabilities. What interests us here is the capacity of the entire soil column; it therefore depends on the soil section. Regarding the effect of the volume of rains and antecedents, we have to take humidity into account by known methods;
– Again a rain of enough intensity that the water cannot infiltrate at the rate at which it falls. We then observe a runoff which depends on the intensity of precipitation, and the maximum infiltration speed in the soil considered. These characteristics are of particular importance for soil erosion.
Rain infiltrations that reach the water tables act on their level very quickly, with only a lag of less than a week. However, the well fluctuation curves almost never show such rapid reactions: the shift, from the maximum of the inputs and the maximum of the aquifer levels (measured in wells), is 1 to 3 months; this delay is necessary for the infiltration wave to be transmitted to the wells.
Although less important as a source of water supply than runoff, rainwater constitutes a considerable contribution, if abundant falls occur before the spreading of floods, to prepare the infiltration of these, in raising the soil moisture level.
Ultimately, the estimates obtained by these different methods allow an infiltration rate of 5% to be assumed, that is to say that, on the 20 m3/s that fall on the Haouz, the infiltration is evaluated at 1 m3/s.
Finally, the water table still receives 1 m3/s fc of re-infiltration, from the 6 m3/s which, good year bad year, are extracted from the ground by the Khettara, wells and sources.
b— Exports of the aquifer
Departures from the water table include net withdrawals – the difference between gross withdrawals made by artificial dewatering systems installed by man (Khettara, pumping, managed sources) and infiltration – and the product of natural drainage carried out by Wadis, working laterally as collatures: Nfis (457 1/s), Hjar (424 1/s) and especially Tensift (2442 1/s). All these directly measured figures pose no particular problems.
Below are two diagrams showing the balance sheet and the jation of water in the water table of Haouz, and a table, which gives the main figures summarizing this assessment.
Manipulating the figures in this table and balance sheets of water circulation, would not give very rigorous results and they must be taken as a rough, instantaneous synthesis, in steady state. The arrangement of the analog model, on the other hand, makes it possible to solicit with prospective dynamic scenarios (development schemes), or past ones (state of the water table at such and such a time of the year or of history), available data. For example, we know approximately what was the hydraulic network, the importance of the Khettara levy, under the different dynasties, as well as the approximate extension of the marshes downstream of
Aghmat and on the banks of the Tensift. Calculation programs are being studied in the spring of 1974, to be introduced into a computer, to allow a more precise appreciation of the extent of the irrigation network, and to ask more relevant questions on land use at different historical eras.
In summary, the waters of the aquifer come from:
– Or floods, infiltrating the bed at irregular intervals desiccated Wadis or in flood areas (the latter unimportant);
– Or, on a much more regular basis, infiltrations on along networks of earth canals (Seguia) or on areas for spreading irrigation water;
– Either by percolation along the underground path, old Wadis beds with high porosity and permeability;
– Or, finally, directly from the precipitation that occurs on the plain.
This acquired knowledge allows to represent the Haouz hydrogeology fairly precisely. The polls carried out show that there are no deep aquifers and that only the neogenic and quaternary formations, of continental origin, contain an important and generalized aquifer. But these continental formations are very heterogeneous and of very variable permeability. The latter decreases from the surface to the depth, the facies becoming more and more clayey. The water table therefore circulates practically in the upper part of the continental filling that is to say in the Pliocene formations reworked by the Atlas Wadis after the end of the folds, and in the Quaternary formations.
|Injection into the water table||P. brut Khettara source well||P.
|Tas rhi mont||179||1 510||810||700||424||1 750||2 984||Hjar|
|Zat||4 370||2 620||752|
|Ourika||5 120||4 3.10||2 011||1 110||730||380||810|
|Rhirhaïa||1730||900||1 245||790||590||200||457||830||3 617||Nfis|
|Nfis||5400||3 070||1476||960||520||440||2 330|
|2 442||2 442||Tensift|
|Total :||16 620||10 900||6773||6 J60||4 410||2 050||3 323||5 720||9 043|
- = bypass Sources: exploitation of the Haouz 2/1972
P = samples Analog Model.
R- = reinfiltration Units: continuous fictitious liters/second.
The useful edge of the tablecloth, of relatively small thickness, de-rarely passing forty meters, is heterogeneous vertica- as well as laterally. This heterogeneity, no doubt due to ramblings of the old Wadis, results in the existence of channels high permeability which is the seat of preferential underground flows.
The supply of this groundwater comes, as we have seen, mainly rains having trickled into the Atlas catchments, and the infiltration of rainwater in the plain, mainly on the debris cones. The vertical infiltration of the rains that fell directly on the plain is very limited, due to the generally not very permeable nature of the alluvial cover, which the level of the aquifer tends to raise. The pumping system therefore tends to unbalance it.
The isobath map, drawn up from the survey of water points, shows that the depth of the water table tends to be greater the higher the altitude of the natural terrain.
This is how it generally decreases from south to north (moreover, from 60 m in some places on the southern edge, less than 10 m on the northern edge). The deep geological structure of the basin also has an influence: southwest of Marrakech, the presence of the Azofid fracture results in a sudden deepening of the water table. The existence of privileged feeding zones, along the course of
Wadis, appears clearly, in particular for Ourika, in the axis of which the 10 m isobath curves until it touches the piedmont. Finally, zones of depression of the water table are detectable, which correspond to zones of overexploitation; the largest is in the pumping area located west-northwest of Marrakech (Targa-Mrabtine region) and another in the southeast, in the pumping area that supplies the city.
A particularly interesting indication of the map of isobaths is that of the zones where the depth of the roof of the water table is less than 10 meters, a depth which corresponds substantially to the economic limit of pumping (taking into account the drawdown of the water table caused by racking).
This depth less than 10 m appears in three regions main:
– the Tensift border area, which stretches for almost a hundred kilometers in length (from downstream of the confluence with the Nfis to Tamelelt) and over a width varying from 1.5 km (at from the Mrabtine overexploitation zone) at 17 km (at the bottom
Nfis). Its surface is approximately 600 km.
The groundwater flows from south to north-west or north, that is to say from the Atlas to the Tensift. The natural outlets of the water table are formed by the springs or resurgences of the left bank of the Tensift (which locally detaches the water table).
Temporary accumulation of infiltrated water quickly translates by a bulging of the water table, under the feeding zone. When the feeding stops, the bulge subsides then disappears downstream, carried away at a speed higher than that of the aquifer (phreatic flood). It is understandable that the amplitude of the fluctuations of the aquifer is higher in the zones which undergo marked annual alternations of supply, than in the regions where the aquifer only transits, without receiving inputs or being subjected to sampling. These are of three types, the effects of which are different:
– in the area of Khettara withdrawals, during the period when the water table rises, the uptake increases, hence the reduction in its flow further downstream; during low water periods, therefore when its level drops, the setting flow decreases, a tendency which is opposed to the continuous decrease in the flow of the sheet during its journey. In both cases, the Khettara function as self-regulating systems;
– in the area of pumped water withdrawals, during periods of low supply, the increased need for water tends to increase the withdrawals, hence lowering the water table; in humid periods, on the contrary, the importance of pumping decreases;
– the border area of Ourika Wadi, which cuts across the Haouz plain from south to north, where it joins the Tensift border area. Surface: about 250 km.
Thus, in total, the areas under which the water table is less than 10 m deep cover nearly 850 km, or more than 40% of the Haouz plain.
THE CLIMATE OF THE PRODUCTION POINT OF VIEW
AGRICULTURAL AND PASTORAL
The Haouz is subject to the arid-hot Mediterranean climate, characterized by low and variable rainfall, a high average temperature, showing strong monthly and daily variations, low humidity and high evaporation.
Although undergoing a very contrasted climate, the bottom of the plain experiences only exceptionally frosts, but it is crossed by hail “corridors”, and often suffers from hot and drying eastern winds, sometimes even in winter.
The severity of the climate of Haouz has always been stressed and especially in its summer excesses:
“The traveler who crosses these territories in summer is struck by the desert aspect of the stony areas where crops are uncertain outside the rainy years, and where the herds are numerous roam in search of a rare grass. The rock or the silty plain dotted with jujube mounds extend as far as the eye can see under intense light and are periodically swept by the sand wind ”(R. NEGRE);
Or again… “The unity of the plain (du Haouz) is not a simple illusion, a mirage caused by the dust and the vibration of distant places in the heat of the day” (J. DRESCH);
But a striking contrast “in Spring, the rocky or silty plains disappear under a thick mantle of flowers of all colors where locally dominate the white of the bitterns and asphodeles, the orange of the marigold, the yellow of the mustards, the red of the poppies and iris purple. These marvelous multi-colored carpets stand out against a background of bluish mountains still covered with snow on the upper slopes and form landscapes of great beauty ”(R. NEGRE).
The Mediterranean climate, hot and dry, continental type, Marrakech, is classified in fact, according to the Thorntwaite indices, at the limit of semi-arid and arid, so that the slightest displacement at altitude and even in longitude varies climate conditions quite appreciably. In addition, Haouz is located east and south of two distinctly more arid groups, centered on Chichaoua and Sidi Mokhtar on the one hand and the Bahira depression on the other: it is bordered to the south and south is by semi-arid and sub-humid layered areas. It will, therefore, be understood that the climate of Haouz if it is characterized by strong contrasts over time, is not homogeneous in space either.
Their annual distribution is characterized by:
– A rainy season from October to April-May, presenting two November-December and March-April maxima:
– Almost absolute drought in summer, with very hot weather and Drying winds (chergui, sirocco). The months of June, July and August total less than 5% of the average annual rainfall.
In the plain, the average annual precipitation decreases from east to west, at a substantially equal altitude: 260 mm in El Kelaa, 237 mm in Marrakech and 178 mm in Chichaoua. As is normal, rainfall increases with altitude: 346 mm at Aït Ourir (660 m), 437 mm at Tahanaoute (925 m) and 691 mm at Agaïouar (1805 m).
Number of rainy days (1925 – 1949) (Days during which the precipitation is greater than or equal to 0.1 mm).
- DÉBRACH, J. OUNET and M. MICHEL, Annales Phys.
Globe I.S.C. 1956 t. 16 pp. 77 – 108.
Henri DELANNOY has excellently shown how the rainfall regime varies zonally, € t confirms by a rigorous graphic presentation, CE that qualitatively we sensed: the existence of a rainfall gradient, increasing from west to east, from Chichaoua, due especially to an increase in spring precipitation in the east. In other words, at the beginning of the agricultural year and until January, the total amount of precipitation is not significantly different in Chichaoua, Marrakech and Kelaa des Sraghna.
It is from February that the rainfall of Chichaoua is clearly distinguished from that of the two other stations. This observation, to a lesser degree, also applies to the left bank of the Nfis; the farmers point out that the “hail corridor is the rain corridor”, and they locate its western limit along a line going from Taguenza to Tahanaout, ie roughly along the course Nfis; but it is mainly then the rains from the north and northwest sectors which, in the spring, are the most expected.
A second gradient with a much steeper slope is that which goes from Marrakech to the south. There plays the well-known effect of altitude on rainfall, but this effect is nuanced and modified by the forms of the relief, the oppositions of the slope and the existence of the valleys which pierce the massif and open turbulent circulation on the heights landforms. The low density of stations and the subjectivity of farmers’ declarations make it difficult to make a rigorous assessment of these variations.
We can however admit that the same growth in the rainfall from west to east exists along the dir, and especially at the level of the forefronts, its effects are particularly sensitive on the distribution of the vegetation (Chamaerops humilis – ar. Doum, descends to 500 m on the Zat course, while it is 650 m on the Rhirhaïa).
If the Aghmat farmers are to be believed, it is raining more on the in Tasrhimout and on the Jbel Sahl, both in winter and in spring.
At an even more detailed level, the slope exposure effect is extremely clear, especially on the dir of Tendrara, the Jbel Sahl and Tasrhimout, less pronounced on the mountain proper.
The interannual variability is very marked: from 137 to 468 mm at Marrakech (period 1924 – 1963); from 126 to 449 mm at El Kelaa (period 1928 – 1960); from 115 to 604 mm at Chichaoua (period 1928 – 1961). Rainfall can therefore vary, depending on the year, in the proportion of 1 to 3.5 in the Haouz.
We talked a lot in Marrakech, in European agricultural circles peens, of the succession of sequences of rainy years and dry years; they were called cycles, which climate data does not seem to show well. However H. DELANNOY draws up a graph of overlapping averages over ten years, in order to cushion the effect of annual fluctuations, which gives weight to what we took for legends.
Moroccan farmers are, however, more philosophical on this subject; in any case, for them, the total annual rainfall is not of great interest: only the rain that falls before December in the mountains and after the month of February on the Plain counts; the irrigations do the rest.
This explains the extraordinary situation of Ourika compared to other basins, because it culminates in the highest peaks of the Atlas and therefore benefits from the latest melt, and, thanks to its virgation, it is placed far enough east to receive more spring rains. Although less abundant than Nfis, it is in many ways more advantageous for irrigated agriculture.
It interests heights from October. But the first snow do not hold, melt on the ground, and it is generally necessary to wait for the beginning of December, so that they occupy the mountain range without interruption, until April. Long before the first falls, from September 10, the herds in the alpine pastures return to the villages, the cattle to be laid down, the small cattle to graze on the lower slopes. When the snow suddenly seizes the mountain in its mass, the sheep and the goats are, in haste, sent to the plain. Those who are surprised must stay a few days in the barn consuming precious hay cut during the good season and reserved for the dairy cow. But most of the time the “descent” of the snow at altitude is progressive, and pushes back the herds of the Atlas step by step, day after day, slowing their walking as best as possible, so that they arrive in the plain when the shoots herbs from the first rains will already be large. Pacts (amgôn) bind, or rather still bind recently the mountain dwellers and the pastoralists of the plains: (Goundafa and Rehamna, Masfiwa and Rehamna Brabiche…).
From March in general the snow recedes, the melting feeds the Wadis, but we can still expect abrupt and spectacular returns. On March 20, 1974, the snow fell to Akhlij (800 m) and Tahanaout (925 m) and lasted two days.
In early May, the sheep slowly return to the heights. Very ancient traditions regulate this rise. A functionalist theory would suggest that the breeders are only thinking here of wise management of the pasture while respecting a delay sufficient for the growth of the grass. We believed it at first, but it is not sure: at the Yagour (2400 m) the climb is done on the first Saturday in May Julian while at the Oukaïmeden (2200 m) it is, or rather it was, August 1, Julian. In these high places, the pre-pastoral gods still remain hidden, and the worship which one returns to them interferes as much with Islam than with pure pastoral practice.
Snow in short 2, in Haouz, three roles:
– It is the best possible dam to retain a considerable body of water, which it delays the delivery in the Wadis, and allows arboriculture in the plain, in the absence of any important hydraulic building;
– It slows the vegetation in the Haouz by the air mass that it cools in winter;
– It regulates the circulation of the sheep flock and the flock residual mountain goat.
Let’s add that it does not fail to give a touristic dimension tick in the high mountains.
But its geography is still poorly understood, and we would have liked have more precise information on his diet, in order to be able to understand certain aspects of the hydraulic flow of the Haouz rivers.
Although rare (1 day per year on average) hail from spring storms is devastating in Haouz, especially for orchards. As with other precipitation, the years are very different from each other. From 1958 to 1963 there was no fall of hail, the wrestling associations were stripped and disbanded. But since 1964, each year, hail has wreaked havoc, and especially in the spring of 1968, causing damage estimated at 5 million dirhams.
b— The temperatures
: Vegetation in Marrakech suffers from cold rather than hot. If the high temperature has a disadvantage by increasing sharply evaporation and evapotranspiration in an area with low humidity, and therefore increases the water requirement of plants, its effects can be relatively combated by irrigation and windbreaks.
On the other hand, the cold, as soon as you come close to the mountain, appreciably delays vegetative growth in a region where there is no lack of sunshine. Should we explain by this the lack of ripening of dates in Marrakech and the fact that the Saadians preferred to cultivate sugar cane in Chichaoua rather than in Marrakech?
The following figures, recorded in Marrakech, are roughly valid for the whole of Haouz: the annual average temperature is 19 ° 8 (11 ° 5 average for January, 28 ° 8 for August); the average annual minimum temperature is 12 ° 4 (January’s is 4 °, August’s 19 7), the absolute maximum is 48 ° 1 (July 1943), the minimum – 3 ° (February 1935). The continental character of the climate therefore clearly appears through these figures.
c – Hygrometry and evaporation
The monthly average in Marrakech increases from September (51.2%) to January (70.2%), then decreases until August (43.5%).
The average annual evaporation (Piche) is around 2,300 mm,
varying as follows for the period 1949 – 1953:
The number of sunshine days per year is 240, of which 114 are continuous sunshine and only 6 days of zero sunshine. In total, there is an average of 3,245 hours of sunshine per year.
d— The winds
They are dominant from west to northwest, but the climate is deeply influenced by the existence of hot and dry winds:
– The chergui blows from the east, generally in August – September but can occur at any time of the year (for example December 31, 1961);
– The sirocco blows from south to southwest.
The average annual number of days of chergui or sirocco to Marrakech reaches 39.
The few figures above, reveal the essential characteristics of the climate of Haouz: annual variability marked by rainfall, coincidence in June – July – August of almost zero precipitation, high temperature and low humidity gusts of wind dry and hot causing a strong eléwemn of the temperature and a sudden collapse of the hygrometry, strong of the Pdiurnal – nocturnal of the temperature, with risks of Vans but no spring frosts, strong diurnal lowering of the hygrometry in summer.
It is obvious that such severe conditions impose strict constraints on agriculture. In winter, demanding plant growth a lot of heat is impossible; the other plants can develop but their production is very random without irrigation. In summer, irrigation becomes essential for all cultivated plants. In addition, crop yields are subject to strong interannual variations, depending on the variability of rainfall and the possibilities of irrigation, particularly with regard to cereals.
An agronomic study of the climate concluded in 19647: “without irrigation, the climatically possible crops are established as follows in the low plain of Haouz:
Shrub crops: Date palm (incomplete ripening)
Forage crops: Atriplex halimus and semi baccata,
Festuca and salsola
Oilseed crops: Safflower
Cereal crops: Wheat and barley (with less than 4 gx/ha yield).”
The olive tree itself was excluded because the annual water deficit of this tree is, in the climate of Haouz, 20 m °; with a slope of less than 2%, no surface development, apart from irrigation, allows the deficit to be filled; the same is true for almond and carob trees.
In short, there can therefore be no sustainable agriculture in the Haouz without irrigation, and agricultural development is closely subject to optimal use of available water resources.
THE PLANT LANDSCAPE OF HAOUZ
The current vegetation, as it is known by phytosociological studies is the result of a complex desertification process, the different factors of which are not easy to highlight.
The various authors agree to classify the Tensift plain in the arid Mediterranean vegetation stage (warm understory) and recognize as characteristic species of the climax, the jujube (Zizyrphus lotus, ar. Sedra), the pistachio of the Atlas (Pistacia ailantica, ar.} And Acacia gummifera (ar. Talh).
At the climax stage, the plant population of what will later become the Haouz, should appear as a fairly homogeneous formation where dominated on the slopes, below 550 meters, the jujubre in vigorous shrubs with, below, a few pistachio trees. Between 550 and 700 meters to the south, on the Dir, the dwarf palm (Chamaerops humilis, ar. Düm) spread out in broadsheets – already characteristic of a semi-arid climate – overhangs by a complex forest cover of mixed olive trees lentisques, with, in places, occupations of Thuya ‘. In the lower ground. ”Voues aux Marécages crossed rushes, by tamarisks (Tamaris gallica, ar. Tarfa ‘) themselves overtook by poplars (it is mainly P alba, – ar.
Safsaf -, not aspen, nor birch, as is too often said error). On the slopes and ridges of Jbilète, the semi-arid climax plant formation consisted of dominant wild olive trees (Olea oleaster, ar. Zebbüj) with some pistachio trees; Jujubiers being much rarer and hardly visible in this formation.
Thus the screen of the High Atlas in the south and the Jbilète in the north of Haouz, reverse the succession of climatic stages which from west to east, from the coast, went towards aridity, creating phytoecological itions very comfortable for such latitude, if we compare them with that of Figuig for example, or the same distance to the sea (Benguerer).
In the Haouz, R. NEGRE significantly reduced the area that L. EMBERGER reserved for the arid floor *. Ch. SAUVAGE makes the remark and explains it by saying that “the criteria used by R.NEGRE are only floristic” and consequently that “the limits drawn… correspond to a slightly different conception of the arid stage”.
This controversy is of great interest to us because it allows us to understand a little better the historical succession of vegetation types and, consequently, the natural conditions of human occupation before the historical period.
The main climatic formation is a discontinuous thorny thicket which occupies the wide slopes of the plain, and which can be primitively called a high bush (EMBERGER), rather open, in which the jujubiers of a beautiful coming, and the pistachios much less numerous, would be comparable to those that can be seen today in cemeteries7. The root system of the non-coppiced jujube, in the situation of primitive competition, keeps the shrubs at a fairly significant distance from each other, generally greater than 30 meters. The bush in the jujube tree must have been of an approximate density of about ten trees per hectare. Obviously, the edaphic conditions can vary the stand quite appreciably. In particular, the proximity of the aquifer reduces the horizontal path of the root system, a rocky soil, on the contrary, favors it. Denser on deep lands, well supplied with water, as on cones and high terraces of Wadis, or in thalwegs and gullies, in riparian formations, the bush was on the contrary more open on plateaus and basins with skeletal soils more or fewer limestones from Guemassa and • Tamesloht. Between – and under – these shrubs, grew bushes accentuating the physiognomy of the bush; and in the voids left by the bushes, according to the seasons, the therophytes and cryptophytes spread their vegetal carpet.
There is every reason to believe that the current distribution of vegetation very poorly accounts for climax groupings. Indeed, although not very dense, the shrub layer, reinforced by the layer of bushes, constituted a cover developing on the ground a protected micro-climate, wetter, cooler, creating more favorable soil conditions, less eroded soils, therefore more independent of bedrock or reworked lithology. In these more comfortable circumstances, the competition between the different plant species had to be very different, achieving the best balance with the general climatic conditions relatively buffered at the level of the mesoclimate and relatively indifferent with regard to local conditions, except for the specific hydrological balance. There therefore emerges from this the feeling of a horizontal homogeneity of the plant population but of a greater vertical structure within the formation, and at altitude. This does not mean that the richness of the floristic composition was not great, it later showed that it had a fairly considerable stock of possible responses to anthropic aggressiveness, but we mean that the manifestation of this wealth could be felt less due to relative ecological homogenization.
In any case, it should be considered that the climax plant mass was powerful enough to maintain a strong animal biocenosis with large ruminants and the corresponding predators. Prehistoric life, as we know it today thanks to more than a thousand engravings found in the Atlas * suggests the existence of a period – contemporary with bronze, or just before iron – when the man was engaged in catching cattle, at the dawn of a regular collection from wild herds, in the midst of a fauna of herbivores and big cats10. The capture pastoralism, combined with hunting, was certainly not without large displacements, or at least transhumance, taking into account the climatic conditions which plagued the winter on high pastures: the Yagour and the Oukaimeden are located between 2000 – 2700 m. We can identify the downhill corridors in the plain by engraved stone tags, lifted at the outlets of the Wadis, at Dir, west of Rhirhaïa and between Zat and Rdat. Did the bovid hunters – pastors linger in the plain which will become the Haouz, or did they immediately cross the Jbilète to access larger, less wooded areas, near the two large lakes of Bahira and from Zima? We don’t know anything about it except that less than half a century ago – but perhaps for other reasons – transhumance still combined the short sway on both sides of Dir with the great transhumance by the same corridors up to the Hadra. Around the lakes, prehistoric studies point to the establishment of tribes of fishermen-hunters, who must not have dealt great damage to the natural vegetation.
What could indeed be the human density, and at the technical level then, the anthropic effect on the vegetation? Probably very small, the consequences zero in the Haouz itself. The absence of any lithic industry between the Tensift and the Dir despite intensive research by prehistorians, while on the contrary, the vestiges are abundant on the right bank of the Tensift, in Bahira “and in the Atlas, must give us to reflect on the inhospitable nature of the plant cover and the ecosystem. The tree layer made up of pistachio trees, but also thorny jujube trees, should not have been convenient for circulation in an area where the rivers, ending towards the Tensift in swamps, had to compartmentalize the territory and limit passages to compulsory points. The routes of movement should rather be along the heights, on the Jbilète on the right bank, or along the Dir, on the plateaus or basins less abundantly covered and where the tree layer was more open. However, it is precisely along the line of the Foum and on the hills of Musiha (Mouissira des Cartes, near Tam esloht) that we find raised and engraved stones. Travelers, even after the founding of Marrakech, are more willing to take the Dir road to travel in longitude, perhaps because the first stopover cities were established on the Dir for historical reasons, but also because that traffic was easier there.
In general, Arab geographers and historians agree that, at the beginning of the 11th century, when Marrakech was founded, the plain was still covered with brushwood, the shallows being occupied by swamps. Jannâbi12 specifies that poplars were growing around the city. DEVERDUN rejects this clarification13 wrongly, it seems, because NEGRE admits very well the existence “at the edge of rivers and swamps of poplar and tamarisk wood that can reach more than 10 m high”
The process of degrading the plant cover must have been slow at first and should not accelerate until very late. Without involving a significant change in the climate – which may have played its role in aggravating the phenomenon15 – the decrease in density of the trees, that is to say of the upper stratum, set in motion a progressive mechanism of exposure of strata lower than the rigors of the arid climate and its variations (daily, annual, multi-year). As the micro-climate at ground level is less difficult to escape from the general climate, competition between species is opening up to tend towards a new situation of equilibrium, minimum entropy, more directly dependent on the station. In addition, the significant reduction in plant mass per unit area greatly modifies the edaphic conditions, the hydrological balance (evaporation and evapotranspiration) punctual, the thickness of the soil and, consequently, makes the plant group more dependent on the rock. or lithology. Ph. STEWART was able to show the self-aggravation of the sterilization phenomenon. We are well aware of the consequences of the reduction of plant cover on increased erosion: reduction of plant transpiration, increase in temperatures, etc. The degradation of the soil-less and less worked by the biological mass makes lower the fraction of precipitations retained under the plant, thus to decrease the lowering of the temperature of the potential evapotranspiration, and so on. Today we can see the existence of a large number of plant groups, very diverse, very varied and of a small extent.
While at the time of the climatic cover, the specification was vertical and the homogenization horizontal, with the degradation of the highest stratum we are moving towards a horizontal specification and homogenization, not to say vertical solitude.
So that, to return to the general climatic qualifications. D’EMBERGER, to say that the vegetation of Haouz belongs to the arid stage, even when specifying (warm understory) characterized by Zizyphus lotus and Pistacia Atlantica, is today only an abstraction designating a homogeneity and an identity dead, a signpost planted at the edge of an old road, evoking the name of a disappeared and untraceable city. In other words, the hot arid climax of EMBERGER was much less arid on the ground than it is today.
It is not necessary to assume that, to achieve this result, the pastor had to engage in a campaign of frenzied deforestation as some authors have complacently stated. Besides, it would have been very powerless to root out the jujube tree: those who have practiced land clearing and motorized cereal cultivation know very well that this thorny plant is not easily overcome. Better, one can assure that the extension of agriculture extended the jujube tree, not only beyond its limits, by increasing its territory to the detriment of the dwarf palm for example, and making it gain altitude which could be taken, after all, as a desertification but in density on its own territory, on the surface, but not in height. Also we can discuss the accusation of destruction against the nomad and the pastor: neither the shepherd nor the goat are really interested in the trees, and when they do, it is never in a massive way, but rather punctual and dispersed.
On the other hand, the sedentary ones have greater needs in thorny, in wood, and they occupy radio centrically the space in sheet; they first exhaust the neighborhood before going further, their action is more concentrated, more massive and therefore irreversible. But, for a few decades, the expansion of crops ceased, and we saw the re-emergence of the jujube tree, and gradually reestablished a thicker plant population. Travelers who follow one another on the same routes throughout history can be accused of subjectivism, but it is all the same surprising to note the contemporaneity of the great epidemics and the great political troubles with the description of a nature “returned to the wild ”. We will have the opportunity to come back later on the importance of the cycle of drought, famine, plague, political unrest, which several times blocked the accumulation and made the country stagnate, but we would only like to quote here two testimonies on the same places, sixty years apart after the great plagues of the first half of the 17th century:
“Jean MOCQUET (1601 – 1606), SIHM 1st series Fr. II p. 401: “Outside the city (of Marrakech), in the surroundings, through the countryside, there are a large number of gardens and orchards with all kinds of fruit and vines, with water and a small house to go and recreate; they hold some slaves there to work. There are no trees in the countryside except a few palm trees. All the trees are in gardens which are like our orchards”.
Thomas Le GENDRE (1665), SIHM 1 ** series Fr. III p. 717 & 721: “The countryside between Morocco and the sea has no towns, villages or borgades, but only traveling douars …
Even the mores have no possessions or gardening beyond the reach of the city wall mosque, because they did not enjoy it, the Alarbs would steal at night; which is why these people do not cultivate and do not use the goodness of their countries ”.
The fluctuations of the natural plant population are ultimately quite difficult to know in the course of history, but they can be deduced, in part, from the alternations of the irrigation of the land which will be the subject of a particular chapter. To summarize the main features here, let’s say that the most sensitive phenomenon was the installation of the city of Marrakech north of Haouz, capital of Empire and metropolis, which had to require huge quantities of wood for cooking food, heating baths, bricklayers and potters, the sugar industries, dyers, saltpeter, metal smelting, etc. Second, the extension of the groundwater drainage by the Khettaras well come back to that, which resulted in a dramatic reduction in marshes east and north of Marrakech. Finally, increases – often followed by regressions, it is true of intensive irrigated agriculture (cotton, sugar cane, orchards.) Which could not be done without complete and massive clearing.
We should also be more surprised by the resistance of the natural plant environment than by its degradation. If it has endured, it is certainly due to the fact that the development of Haouz has never been very complete, nor very durable: Almoravid prosperity did not last 25 years out of the 64 years of reign in Marrakech and did not interest more than 5000 hectares. It was a little before 1160 that the Almohads, finally, managed to take care of their capital and engage in major hydraulic works: 15,000 hectares in all will be irrigated at the height of their glory, but for less than 70 years. After which the long Marinid night opens for Marrakech, which remains within its walls, and sometimes even sees its water supply lacking. There is every reason to believe that in the middle of the 16th century the Haouz returned to the situation left by the Almoravids. The Saadians were great irrigators and really settled in Marrakech from 1150; but a terrible plague struck the whole country in 1558-59, and we can date with precision (the references will be given later in the chapter on hydraulic development) the repair of the Tassoultant and the impoundment from the central Haouz, abandoned since the Almohads, in the year 1578. The Saadians irrigated around 20,000 hectares in the Haouz. But from 1650, significant regressions began to be felt. Under the Alaouites, it was not until Moulay Abderahmane (1822) and his son, Sidi Mohamed, who were the first great irrigators of the dynasty, that the séguias of central Haouz were revived. Admittedly, the irrigations of the Ourika and Nfis valleys had not been significantly reduced since the end of the Saadians, but the entire center of Haouz had returned to the bour.
In 1915, the tertib recorded a total of 20,000 hectares cultivated in the Haouz, of which 98.6% in cereals and less than 300,000 olive trees, and in total 5,000 hectares irrigated. By way of comparison, the 1960 tertib gives for the same space 2 million olive trees and 80,000 cultivated hectares, 70% of which are in cereals. In short, if the degradation of the natural vegetation in the Haouz is a process started a thousand years ago with suspensions and backsliding, it is only sixty years ago that the means to overcome it used.
The spots on the maps of plant associations are relictual in most areas and therefore can only really interest the botanist. Massively, the haouzian space is occupied by the cultures, and the jujube tree which remains still visible is irremediably condemned.
THE SOILS OF HAOUZ
The soils of Haouz were formed on the alluvium deposited during the different episodes of the quaternary. These were partly intersected and washed away, during the erosive phases corresponding to interpluvial; others have been covered by deposits from the rain fill phases. Once in place, the alluvium – parent rock, has undergone changes linked to successive climatic fluctuations, then to recent climatic actions, finally to anthropic actions.
Soils, as we see them today, are the result of all these changes, sometimes separate, sometimes parallel.
Without going into details, we can sum up to six main phases the story that dominated the formation of the soils of Haouz:
– the saiétien (corresponds to the glaciation of the Günz in Europe) cold and humid, with glacial and periglacial dynamics, with erosive periods all the same to the melting of the snow, evacuating the products in flushing and forming, at the bottom , solifluxion zones then lakes and daya with intense gelation. These actions cause fragmentation of hard rocks into angular biocailles and deposits of wet clays; the soft rocks, are deposited in stony masses of large calibers: ranas of the Zat Wadi very characteristic at the Tafériat level, less clear at the base of the cone (and perhaps also in the Rhirhaïa – Ourika intercone) located on the high stony terraces, little or no encrusted;
– After a warming period, calmer from the point of view of deposits, the mild and damp Amirien (corresponding to the episode of the Mindel glaciation in Europe) acts mainly by chemical degradation in the mountains and spreading deposits muddy, clayey, little stony flows if not by the resumption of the Salesian stones. The reddening of the clay mass gives these soils their characteristic color in the cones of Rhirhaïa and Ourika;
– The Tensiftian (corresponding to the Riss glaciation), with a cool and humid climate on the plain with strong climatic contrasts, cold in the mountains, ends with an episode of heavy rain and very active torrential activity. This is an important period in the constitution of medium terraces with deposits of pink silts and pebbles in inter-stratified beds with, at the end of the rain, local lamellar crusts. From the point of view of pedogenesis, we make this phase responsible for the individualization of limestone in granules and nodules in the upper layers explored by the root system of plants;
– the Soltanien (Wurm) experiences an alternating climate, cool wet first with erosion of previous deposits especially in Ourika and Rhirhaïa, less visible in the cone of Nfis which is too far downstream from the foothills in which it’s” is cashed, little or not in the Zat. A humid and milder climate comes next and causes clay and stony deposits. At the end of the period, a return of the cold brings about a weak recovery in erosion in the mountains and accumulation in the plains, responsible for constituting a large part of the cones (Zat especially, but also Rhirhaïa and l ‘Ourika and the deep layers of the Nfis cone) and a verification of surface horizons;
– Finally, the current climate, hot and dry, has led to a resumption of regressive erosion of the rivers of the Tensift basin. Surface runoff, the erosive action on the ground, has led to the well-known phenomenon of the beating of the soils of Haouz.
Five phenomena characterize the evolution of the soils in the current phase: the resumption of erosion, sterilization, that is to say the evolution of a semi-arid climate towards a markedly arid climate, the salinity in the lowlands where the water table is close (due to summer drought), the anthropic consequences (deforestation, clearing, cultivation, irrigation).
To conclude the overview of the different episodes of the establishment of the soils of Haouz say that, despite the aridity of the region (indicated by the value of climatic indices), the morphological characteristics of the soils encountered rather evoke a pedogenesis of semi-arid climate and cross-check the information provided separately by phytosociology.
a – Soils from an agronomic point of view
The overlapping of topographic conditions and pedogenesis led the authors of the Haouz soil map to distinguish thirty-five types of soils classified into classes, groups, and subgroups of a complexity defying any attempt to summarize.
In addition, the climatological conditions prohibiting most crops without irrigation in the Haouz plain make superfluous and useless an in-depth knowledge of the morphogenetic and agronomic characteristics of the soils with a view to a valid classification for non-irrigated crops. Also, the few results presented below are only a broad synthesis, very impoverished, on the essential of what you need to know about the suitability of soils for irrigated crops to understand how this suitability (or couldn’t) play in the social history of Haouz.
The Nfis cone is covered by brown steppe soils whose texture is mainly silty and whose powdery structure of the surface horizon experiences remarkable salt accumulations, especially downstream and on the left bank, and an almost generalized alkalization. They undoubtedly constitute the worst soils in Haouz if considerations other than pedological ones did not intervene. Most of the left bank, except the Agafai Seguia sector and the Oulja in the upstream half of the Nfis, should be abandoned for purely financial profitability, to pastoral exploitation.
The right bank is less disadvantaged, at least the so-called Jnan Allah and Saada sectors, immediately at the outlet; on the other hand downstream, from the Jblia sector, the soils are quite similar to those of the left bank, the limit being formed by the end of the Rhirhaïa – Ba’ja flows.
The cones of Haut Rhirhaïa, Ourika and Zat are covered by red-brown soils, very favorable to irrigated agriculture, at least in their upstream part. Their medium sandy-clay and silty-sandy-clay texture guarantee very advantageous hydrodynamic qualities of porosity and permeability. These are soils which can receive permanent irrigations, and which have received them for more than a millennium without showing any dangerous development. Less interesting are the soils of the Rhirhaïa – Ourika interconnect where the roughness is strong and the structure is not very marked. Likewise, the low Tensift terraces and the region northwest of Marrakech are made up of poor soils. Salt exists everywhere on the low plain, in alarming proportions each time the permeability of the soil allows an easy drainage underwater relatively low in salt. But on the edges of the Tensift, the upper horizons are too alkalized and often too clayey, to be easily leached.
It is generally accepted that the main cause of alkalization present in Haouz is due to a centuries-old irrigation of soils little worked in its deep horizons, and poorly drained where they should be. The waters of the séguias, especially in Zat, always bring small amounts of salt, which, under the influence of the arid climate (evaporation, capillarity) are concentrated in the upper horizons. When the soils are not permeable, the evolution is towards a progressive alkalization with irrigation.
b – Pedology and enhancement
A comparison of the soil map and the land use map shows that development in the Haouz is largely independent of the quality of the soil. The fairly deep lands (more than 40 cm) are irrigated if they are topographically dominable by the Séguias. The topography and hydrology are the strategic factors of the development. The qualities of the land have had little or no influence on farmers throughout history. The most famous example is that of the Targa sector where more than mediocre soils are found, barely superior to those on the left bank of the Nfis, and where colonization has planted its most beautiful orchards. Undoubtedly an optimum calculation of economic profitability in terms of profit made, from financial investments would tend to specialize the soils in order to make the best use of their “vocation”. However, experience has shown that the availability of water has had a much greater effect than the agrological quality of the soil. The economic, social and political costs of transferring water, and allocating it only to soils that have the best irrigation potential, would be far from being covered by the economic benefits of this allocation. This is still so true, that for agricultural development under irrigation today2. The soil map at a scale of 1/100,000 is only drawn up to exclude soils and calculations of water towers, cannot be crowded with limits roughly allowing the calculation of acceptable irrigation volumes by large areas taking into account of the proportional distribution of the different lands. Leveling, clearing, resettlement, alignment of soils and calculations of water towers, cannot overlap the boundaries between the different soil plots. After which, on a scale of 1/5,000 ‘, a rigorous analysis of the soil makes it possible to decide what kinds of amendments are necessary to improve the irrigation doses that are available.
Geographic distribution of soil categories
|Soils suitable for irrigation||Soils unsuitable for irrigation|
|More or less mediocre||Total|
Sources: Office du Haouz, 1962. Units: thousands of hectares.
III – THE DISTRIBUTION OF WATER IN SPACE HAOUZIEN
The severity of the natural environment in Haouz, which is mainly due to the climatic conditions prevailing in the plain, closely links the development of agriculture to the progress of irrigation.
The agricultural exploitation of the space replaced the pastoral exploitation by diverting the waters of the torrents, first on the low terraces, then on the surface of the cones; arboriculture could only win on annual crops and get out of the Wadis bed with the use of the aquifer; agro-industry, almost free from climatic constraints, can only expand in the Haouz with the accumulation of torrential waters behind large dams.
But if we can follow the progress of the agricultural development of Haouz by this wide orthogenetic movement and the superimposed succession of increasingly efficient technologies, it is far from being so simple during of history and in space.
First, because the lowest technologies require a considerable workforce, the layout of which over the course of history has been dominated by very complex political vicissitudes; secondly because discontinuities and the variety of natural situations, the structure of haouzian space in a way, condition the success of each technology differently: favoring one process here, making another last. Finally, the political and physical partitions of space interfere to cover the Haouz with a multitude of composite forms of enhancement.
A first simplification seems to be possible by distinguishing the conditions of the distribution of surface water from the mobilization of groundwater. From this point of view, the plain can be divided into two zones: an upstream zone where gravity irrigation dominates, a downstream zone where the dewatering water is predominant; provided that we do not omit the existence of mixed zones where the water of the water table is mixed, nor the ribbon of gravity irrigation constituted by the long Oulja of the Tensift.
- THE DISTRIBUTION OF SURFACE WATER – Description
The traditional system for mobilizing surface water is that of the Seguia, the most banal in its simplicity and the most important in terms of the areas it allows to irrigate.
This system consists of a simple catch on the river, feeding an earth channel which, after a more or less long and often acrobatic passive course along the Wadi bed, dominates a perimeter of very variable surface: from a few tens to several thousand hectares. The catches on the Wadis are simple small dams (ougoug) higher (50 cm), oblique to the axis of the watercourse, summarily constructed of a mass of branches, more or less large stones and underbrush. The fragility of these works, carried away with each somewhat violent flood, has already been pointed out; but it must be recognized that this “fusible” nature of the water intakes constitutes an advantage with regard to the risks of saturation of the Seguia which is in fact deprived at the head of any guard or regularization work.
The number and the arrangement of the séguias are very variable according to the Wadis. The catches are located as far upstream as possible, well above the bottom, and the network of séguias is deployed, at the outlet in the plain, in the form of a wide range on both sides of the Wadi. There is a perfect example of this device on the Zat cone. When the water resources are more abundant, the catches are spread out along the Wadi, in its crossing of the plain, the Seguias then forming a network “in herringbone” as in the Nfis.
The course in plain of these séguias, in altitude as in plan, is extremely capricious. The variable slope is still fairly steep in the order of 3% on average, and the course, in general, is winding. If these two characteristics – a steep slope to reduce the section of the canal, a sinuous course to slow down a flow that is too fast – can be explained by each other, the results are not happy from a hydraulic point of view, but it is satisfactory at the technological stage of traditional irrigation.
The perimeter dominated by a Seguia, or hydraulic sector, constitutes a real technical, geographic and human unit. When a Seguia dominates the territory of several different communities, the sector is divided into sub-sectors, each fed by a different channel.
Downstream from the main Seguia, the water is distributed by distributors (mesref). These secondary pipes, which generally follow the line of greatest slope, are of very variable length and importance according to the areas dominated by each of them. Generally, the network of mesref materializes the distribution system of the water towers (ferdia) along the main Seguia. From the mesref to the field, the distribution system consists of a hair of very rudimentary micro-pipes (robta), but whose layout is always a function of the distribution of the land.
b – Efficiency and performance
Almost three-quarters of the irrigated area of Haouz is irrigated by the séguias system which covers an area of 100,000 hectares. This process, which is also probably the oldest, and also the most rudimentary, does not derive from it, on average, 411 million m3 out of the 567 million m3 conveyed by the four main Wadis and their tributaries which cross the plain. We can, therefore, measure the efficiency of the collection by Seguias at 72%. This high rate is explained by the ability of the traditional network to capture low speeds. Outside the major floods that escape it, all the water that flows into the Wadis is distributed by the Seguia. Drawing their life, even their survival, from the diversion of water, the populations established on the banks of the Wadis are constantly attentive, all concerned, and from an early age, by the degradation and faulty functioning of the irrigation network. It is necessary to have witnessed the restoration of a deadhead of a Seguia silted up by a sudden flash flood, to grasp the rapidity of the alert system, the collective spontaneity of the response and the capacity for initiative and organization group of irrigators. It is at this level that solidarities that effectively go beyond those of the family or the lineage between the direct users of the waters actually play.
The substitution of an administrative and bureaucratic framework for collective and traditional disciplines systematically results in a lowering of the levy rate, even with an improved network.
For example, on the Nfis which has an accumulation dam, admittedly of small volume, but which makes it possible to protect the downstream against too strong spring floods, the network efficiency is lower, because it is the administration which modulates the releases and weakened the capacities of the response of the groups of irrigators.
|Average annual contributions 10 m³||Coefficient. * of
|Prel. by the séguias||Coefficient.
|Rhirhaïa||58||18||48||82,7||No dam, traditional management|
Sources: Office du Haouz, ORMVAH, 1968. • maximum monthly contributions (April) minimum monthly contributions (August)
By this, we want to show that the traditional Seguia, is at Haouz the technology adapted to the handling of a small group of irrigators. The management of a dam and the distribution of water through concrete-supported canals, by means of automatic valves and modulated according to water towers planned in advance and very sophisticated, belong to another type of social organization, to which the small community of irrigators is hard to come by.
Conversely, the use of the Seguia in the ground, which derives from the flow of random flows, requiring at certain times of the year constant vigilance day and night, is incompatible with administrative management.
Important for the areas concerned, efficient from the point of view of removal, the network of séguias is defective in its transport: it is very permeable and loses a lot of its flow between the Wadi and the plot.
The network performance (ratio between the volumes withdrawn and the volumes delivered “at the head of the plot”) is very poor. A study has established an average annual loss rate of around 4% per kilometer for the main Seguias, which corresponds to a cumulative loss of 25% after 8 kilometers and 50% after 27 kilometers. Given the average length of the Séguias of the Haouz, which can be estimated at 15 kilometers, the yield of the main Séguias would be around 60%. The losses on the network downstream of the main Seguias (mesref and robta) are difficult to assess, but it is certainly not an exaggeration to estimate them at 15% of the residual flow, or 9% of the total, which would give a average overall network yield of around 50%. This is a very low yield compared to that of a modern, almost watertight network, which reaches 80 to 90%.
The overall efficiency of the traditional hydraulic system, obtained by combining losses from withdrawals and those from the network, reaches 0.8 x 0.5 = 0.4; that is to say that only 40% of the volumes theoretically withdrawn from the Wadis are actually delivered at the head of the plot, while the network of concrete channels can deliver 80 to 90%, a gain of 40 to 50%. These figures summarize the shortcomings of the traditional system for mobilizing surface water.
c – Economy of the Seguia
Arab historians show that the first irrigated areas of Haouz were located in the) oum-s that is to say, at the outlet of the Wadis in the plain. There seem to be several reasons for this, the main three of which are:
– firstly the median position of the forum in the tribal region crossed by winter and summer transhumance;
– then the fact that the outlet is the last defensive position on the edge of the plain;
– but above all because the optimal arrangement of soil and water is at this location.
In fact, in the deep valleys, the water is abundant, but the land is narrow; in the plains, the land is wide, but the waters relatively scarce. Measuring the ratio: volume of water available per area offered for irrigation throughout a valley highlights the optimum achieved around the tank.
In a region like that of Marrakech, a flow of 12,000 mVan/ha uniformly distributed throughout the year, ensures the vegetation of the most demanding species (industrial arboriculture, market gardening, fodder). You can go down to 9 or 10,000 m3 if you can be sure you can serve 300 m3 per hectare every eight days during the hot months. Below 7,000 m3 you can only cultivate cereals, legumes, a bit of market gardening, and trees distributed to the devil along the séguias. Below 4,000 m3 guaranteed, it is “the lottery” and the risk is reduced to a minimum: cereal sole turning with a fallow. We will not deepen here – we will do it further – the agro-economic considerations which play, with others, on the choice of the cropping system, we only aim to fix the ultimate consequences of the effects of some technical factors examined for themselves.
In the mountain valleys, upstream of the fountains, it is a constant observation to see the fields flooded by an overabundance of water which, badly channeled in the vagabond channels of the Wadi bed, leaches the land to make a near-sand. Measurements made in the Ourika Wadi show that certain plots are crossed by water doses greater than 50,000 m3 per hectare per year. The duration of sunshine being reduced in these valley bottoms, even in the height of summer, the average temperature is low. Plant growth, plant mass and its evapotranspiration are much lower there than in the plain; as a result, the crops there consume less water. Farmers can only fight against the permanent leaching of their soils by constantly pouring in increasing volumes of organic fertilizers; hence the evolution towards stable farming and especially towards cattle to the detriment of goats and sheep and, consequently, the need to increase the area of irrigated meadows to cut hay; evolution also towards the increase of spring crops: turnip and corn which are traditional, but also potato and tomato more recently introduced; finally, the rise of crops on the plateaux, the slopes, and shoulders, to seek maximum sunshine.
But the first irrigators of the valleys were not compelled to go towards these ends because they had by family, much more space offered to their choice, and the circulation was less hampered by the particularities and the density of establishment. Today.
In the plain, as you go down there, the situation is the opposite: there the spaces are large, but the work necessary to distribute the water is quickly considerable. It’s in the middle of the movies along the Dir, that the land near the Wadi bed is of an area appropriate to the volumes of water available.
The table below gives the current situation on the left bank of the Nfis. It should not be used to illustrate the situation which should have prevailed over this Wadi at the dawn of historical time, but it explains the phenomenon.
|Left bank of Nfis Séguias arranged in upstream-downstream order||Length in m.||Dominated areas in ha
|Water volumes withdrawn in thousands of
|Seguia lengths per ha dominated||Seguia lengths by
|a||b||C||d = a/b||e = a
|4. Fquih Si Tounsi||530||2,79||20||190||9,5|
|5. Moulay Ali||120||24.50||17||5||0,3|
|6. Agafaï||20 600||1 556||4||13||3.3|
|7. Jdida||20 706||4600||3,2||4,5||1,3|
|8. Tamesguelft||33 200||2000||2||2,8||1,4|
|9. Amzri||24 597||2 800 ‘||3,3||8,8||2,6|
|10. Abdallah Slitine||310||112||6||2.8||0,5|
|11. Taïninnt||10 976||1 600||2||6,8||3,4|
|12. Taziouent||12 016||1 200||1.6||10||6,2|
|13. Taslimt||6 440||900||1,4||77||5,1|
We see in column c from Seguia 5 that the flow is taken by the Seguias, relative to the dominated areas, drops considerably, then decreases more or less regularly. In column b on the other hand, from the same Seguia, the dominated areas suddenly increase and then decrease (sector 10 is a special case, historically explainable)
The second factor that closely determines the geography of irrigation in the huts is the work that must be done to mobilize the water and distribute it on the plots. The technique used is very simple, since it actually uses only undermining and human energy. Diversion dams on the watercourse are rudimentary with the sole function of raising and maintaining the body of water at a constant level, so that water can be brought into the Seguias: also they are made to the devil, mixing branches with large stones and bundles of herbs: they, therefore, require neither much art nor much care.
On the contrary, the construction of the Seguia, and especially of the deadhead, requires a good experience of the field and large masses of labor. We can distinguish two parts essentially in a Seguia:
– the deadhead, which is the water supply channel to the distribution point;
– the distributor part which, from the distributor is almost directly usable to serve the water on the plot.
The art of the Seguia builders is to bring the water to the point of distribution in such a way that. Taking into account the morphology of the natural terrain, the work invested on the dead head is minimum, and the area dominated the maximum. All other things being equal, the smaller the ratio of the length of the deadhead to the dominated area, the more the solution adopted is advantageous, since it will then have allowed the irrigation of large areas with very little labor. Assuming that this work is remunerated by a levy on the production of new irrigated areas, it will be all the better since these areas are large. The previous table shows that it is from sector 5 (columns b and d) that the index becomes much more interesting.
But by reading column c we have seen that we are entering, from the same sector 5, into an area where the volumes of water distributable per hectare are decreasing. What is the point of dominating large areas if you only have very little water to irrigate them?
If taking into account the dominated area could make sense upstream of sector 5 to examine the respective advantage of two profiles or two Seguia routes downstream, this is the number of m³ that must be considered; because what will make it possible to remunerate the work thus invested, it is not the production of a hectare, but the provision of a m * of water, since, in any case, there is surface in excess. Column e is used to approximate the measure of the problem. Except in the case of the Seguia Abadallah Slitine, it is necessary, from sector 5, to build between 1 and 6 meters of deadhead to have 1,000 m3 usable in the plain. Suppose it takes 12 days of work to dig four linear meters of this Seguia and get 1,000 m3, the m3 of water costs the first year twelve working days, and the following years of maintenance of the Seguia (minimal on this scale).
We can try to appreciate the profitability of the operation in subsistence economy. Let us assume that it takes 10 kg of grain to cover the reproduction of 12 working days, of those that allow the mobilization of an additional 1,000 m3 of water, and that 6,000 m3 are necessary to obtain – on one hectare, but here the area does not matter for the reasoning, there is in excess – 6 quintals net of cereals (10 quintals minus seeds, plowing, harvesting and losses in storage). An additional thousand cubic meters will therefore increase the harvest by 100 kg. The operation is particularly fruitful since 10 kg invested once allows the production of 100 kg each year; or make it possible to cram ten times more men.
Also the profitability of the construction of the séguias could not be discussed as soon as the technical process was known; the only factors that could delay the total diversion of surface water was quite simply the availability of labor to dig the Seguias and to cultivate and populate the new lands thus irrigated. For example, a Seguia of 3 km of a deadhead, dominating 800 hectares, requires 10,000 work days for its construction and 32,000 work days for its cultivation. We can take as a base the casement of the guichs in the middle of the last century, at the time of the rehabilitation of the large Seguias of the Haouz by Moulay Abderrahmane: the 800 hectares were occupied by 50 homes on average which could not provide more than working day per day, ie 50 JT/day. The construction of the Seguia alone occupied 200 days (6 1/2 months) to irrigate land requiring 640 days of annual work for the remaining 165. In any case, the under-settlement, ‘indicated by these figures, did not allow to cultivate more than half of the space, the rest, being reserved for grazing, and to affect 30 to 45 days, that is to say approximately 2,000 working days, building the Seguia, so achieving it in 5 years. We understand what constancy and what discipline are necessary to complete such work with human energy alone. The solidarity of small groups allows only to build small séguias under the authority of assemblies of irrigators or the ancestry of a santon. But the great séguias can only be dug under the aegis of great powers, and especially by the Makhzen, the only forces capable of mobilizing large numbers of men to complete the work in two or three months in the form of a chore. In this regard, we have a document concerning the digging of the Sultania Seguia around 1850, forcing all able-bodied men from neighboring tribes (counted, moreover, in tax sections: khoms and ijasen) to come and work on the Seguia, each for four days , by bringing their food, and according to a turn by tribe, strictly established in advance. The cost of digging such a Seguia amount, in sum, for the beneficiaries, to the cost of maintaining the armed force responsible for supervising the work, plus propaganda costs.
These theoretical considerations make it possible to understand why the large séguias in the Haouz of Marrakech, those which extend on the cone and dominate the upper terraces, are not the result of communities, but of the State, great figures or Zaouïa.
The Atlas tribes before the establishment of central power could, almost, irrigate and cultivate only the first two terraces of the Wadis and the immediate vicinity of the cone, at the mouth of the mountain. This is where we find today an intensive occupation of agricultural space involving a very dense lineage organization, based largely on the consensus of the groups. In these sectors, there are few, if any, large stately domains, no State property, no notable Habous; if not some micro-plots dedicated to pious ancestors or to the maintenance of a village fqih.
d – The layout of the séguias
The diversion of water on the right bank and on the left bank, on the low terraces of the Wadi, is done according to two devices:
Ñ fan-shaped if water is abundant in the Wadi: a large number of diversion dams follow one another only a few hundred meters from each other, to exhaust the flow (foums located in the Dir: like the Zat and Ourika);
Ñ fishbone if the water is, each time, entirely derived by successive Seguias; the following Seguias can only be established on the emergences of the underflow; it is this last solution which prevails when the Wadi has a long journey in the valley and the outlet located far from Dir: Nfis.
As these canals are dug and wedged by drawing little water – much less than what they will discharge later – the slope of the Seguia is always much steeper than that which one could give it: for small flow, the losses being very strong, the manufacturers tend to increase the slope. In other words, if the traditional irrigators had had topography and hydraulic calculating devices, they could have dominated a larger area with their same sapes (fig. B) 7. The traditional technique of using a little water at the bottom of the Seguia when digging as the only means of leveling has the advantage of allowing this Seguia to deliver even at the lowest water levels.
In practice, the cones are neither perfect nor symmetrical. In general, we note in the Haouz of Marrakech: a variation of the Wadi bed towards the west; a fairly deep encasement of the Wadi in the cone just at the outlet (particularly clear for the Rhirhaïa and especially for Ourika); finally a wandering of the course of the Wadi in the middle of the plain for Zat and Ourika.
This obviously has significant consequences on the course of the Seguias, in particular:
– A lengthening of the deadhead (part of the Seguia between the grip on the Wadi and the first distribution tap) in bayonet for the Séguias upstream (characteristic in crossing terraces);
– asymmetry of the sectors dominated by the séguias (Rhirhaïa and Ourika);
– a complication in the Zat – Ourika confluence.
The distance between two taps, which determines the width of the sector, is due to topographic, hydrological and historical considerations.
From a topographic point of view, as we have seen, the traditional irrigator seeks to obtain a good deadhead/dominated area ratio. He wants, per kilometer of Seguia, to dominate the maximum of hectares. But when the sector expands, distribution requires extending the network of mesrefs. The width sought is about 2 kilometers but other causes modify this ideal scheme.
From a hydrological point of view, small diversion dams, during low water periods, take up almost all of the water available in the Wadi bed. The catches placed downstream can only derive resurgences. Also, the resurgence sites precisely determine the location of the outlets. The construction of the Seguia, its slope, the holding of the banks, the maximum hoped-for flow stop a specific device that cannot be explained on the ground.
Finally, we will come back to this later, with human groups occupying that which can only be explained on the ground.
Finally, we will come back to this later, the human groups occupying the lands dominated by such a Seguia, have tried, over the centuries, to raise the catch as far upstream as possible, since the one who holds the upstream benefits in abundance of water.
The rivalries around the holds result in that the diversions on the left bank and on the right bank do not take place on the same dam, but on two separate dams: knowing which of these two dams will be the upstream one, constitutes the bottom of the political life of irrigators and their conflicts from shore to shore.
The taps on the left bank and the right bank alternate, and they are generally more and more distant from each other as we go downstream. As a result, the upstream Seguias dominate less land and have more water: only the upstream Seguias have water in summer.
We can therefore speak of the existence, along the Wadi, of an increasingly weak sampling gradient from upstream to downstream.
In fact, this phenomenon is tempered, at least in the upstream sectors, by the practice of returning excess water from the upstream sectors to the benefit of the downstream sectors, provided that the communities of irrigators in each sector agree between them. Otherwise the water is discharged to the Wadi downstream from the intake of the next Seguia.
In addition, the downstream sectors have their reduced surface area at the end, since both the flow rates transported could not validly irrigate (at least 3,000 m */ha/year) the entire dominated surface.
e — Water distribution in the sector
The Seguia bed, as we have seen, is permeable. The losses are a function of the length of the channel, but also of the nature of the soil, and of the catch of the mons. In addition, evaporation takes its toll in summer on open waters. The possible distribution of water at the end of the sector is much lower than at the head. Overall, the result of these continuous variations (m ³/ha/year) crosses the sector diagonally.
In fact, the distribution is discontinuous: because it is done linearly; but also because the population is discontinuous in space; finally, because the losses being strong, by infiltration and by evaporation in summer, at the time precisely of the low water, the irrigators concentrate the waters at the head of Seguia and mesref.
The sharing of waters according to the mesrefs, segments the sector into sub-sectors or finages of villages (K), in which the gradient is established centrifugal compared to the catch in the soil. This theoretical scheme is significantly modified by a curvature of the Seguia downstream so as to reduce, in the end, the dominated surface (L).
J— Extension of the distribution system in the plain
The figure below (M) gives an idea of the extension of the distribution system on two cones of Wadi. This pattern is modified by the appearance during the history of the mobilization of waters by seigneurial or Makhzenian powers. Political power superimposed on the tribal system, an irrigation network confiscating upstream of the waters, which were diverted by rectilinear Seguias crossing the sectors contiguous to the bed of the Wadi and exporting these waters in the voids left between the cones of Wadis (N).
To explain why and how this superimposition on the hydraulic system could be done, it is necessary to evoke more social and political history or the appropriation of land, than technology. Let’s already say that the digging of large seigneurial or Makhzen Seguias could only be done under the rule of an authority capable of mobilizing large numbers of people to irrigate small areas. The contributors or the villagers could not, as we have seen, spend such a mass of working days for themselves. Furthermore, the establishment of a hold upstream is only possible by force, by the exercise of violence which finds its resources in a much larger space than in the sector of séguias. In other words, the sectors of séguias, which roughly segment the tribe or the population, into as many political forces, are more or less balanced. There are hardly any examples that one of these groups prevails so resolutely over the others that it can with impunity add a grip on the Wadi, go back upstream, and irrigate a new surface: only one A political authority that finds its armed forces outside the tribe or the irrigation sector, in a regional or even national space, is able to establish this constraint in the long term. The most remarkable case for its extent (6,700 hectares dominated) is that of Tassoultant- Ourika. But there are a large number of others, of lesser importance, which irrigate the seigniorial and Makhzen Azib-s (Saada, Askéjour, Bachia, Caïd, Talbachat, etc.).
The withdrawal of water upstream, in favor of an azib, has the consequence of reducing the flow remaining for the old system and, especially in summer, the downstream Seguias which previously had water, can come to lack. But for reasons of social peace, and defense of its interests, the builder of an azib Seguia is led to give up some of its water along the route of the Seguia (right of mlou or right of way) from so that the immediately contiguous sectors on this shore benefit from an additional volume of water (see on the map the route of the Tassoultant – Ourika and the benefit that the Taoulelt derives from it).
g – Modern colonial irrigation
The second superimposition was that of colonization with, in 1935 – 1936, the construction of the accumulation dam of Lalla Takerkoust (ex – Cavagnac) on the Wadi Nfis and the concreting of some canals on the Rhirhaïa, Ourika and the Zat.
A practice identical to that of the azib séguias was applied: taken upstream, irrigation of land located beyond the traditional irrigation sectors throughout the passage of the modern canal, distribution of a few continuous liters-seconds to calm the minds, satisfy potential water thieves or gain political agreement.
Modern installations concern the networks created by the public authorities since the time of the Protectorate, even if the “modern” objective is relative and does not always suit them perfectly. Here we will give a simple overview.
On the Nfis there is the only regulating dam of Haouz that of Lalla Takerkoust, built from 1929 to 1935. Its initial gross capacity, 50 million m3, is today only 38 million m3 because of the siltation. It is equipped with a power plant (average annual production: 10 million kWh) and. downstream, a compensation dam intended to regulate the variable flow of turbines water for irrigation. The supply channel, with a total length of 14 kilometers to its outlet in the plain, is dug in a gallery over most of its course: its capacity is 8 m3/sec. upstream of the junction with the bypass canal and 19 m3 downstream.
Downstream of the supply channel, the distribution network has received some very fragmentary improvements, including a siphon to supply the left bank of the Nfis and the partial concreting of some Seguias: Agafaï over 4 km; Targa over 4.5 km upstream and 4.5 km downstream (plus 17 km of secondary canals in the subdivision); Saada for 8 km; Askéjour for 3.6 km. In fact, we have been content to improve the existing network unevenly, to the extent strictly necessary for the irrigation of the settlement lots. The whole gives a clear impression of “DIY”.
Oued Rhrihaïa was equipped with an intake dam built-in 1936, located upstream from Tahanaout. This work feeds the séguias Talougart (left bank) and Bachia (right bank); the latter, with a flow rate of 1 m3/s. is concreted along its entire route (19.6 km) to the entrance of the Arhouatim – Tassoultant subdivision, south of Marrakech.
On the Ourika Wadi, an intake structure, located immediately downstream from Akhlij, feeds the Tassoultant concrete Seguia, 20 km long (flow 1,200 1/s) to the main divider and, downstream, a secondary network in the same subdivision of Arhouatim – Tassoultant.
To this list, we must add the unfinished construction of the Rocade Canal, intended to bring to the western and central Haouz the flows of the Tessaout and the Lakhdar.
This structure, with a total planned length of 125.5 km, was partially completed (its concreting and many additional structures remaining to be done) over 82.1 km. But the part executed is situated downstream, a fact which may seem strange at first sight and which is explained by considerations of a more historical-political than technical order. The capacity of the telescopic channel varies from 26 m ³/s at the head to 14 m3/s at the tail on the part carried out. Of the 43.5 km remaining to be executed with a capacity of 20 m3/s, 8.5 km are in the gallery, downstream of the intake structure on the Lakhdar Wadi. Finally, the bypass canal was intended to receive contributions from the Tessaout Wadi through a “courier channel” supplied by the adductor network of the Tessaout sector.
Thus the central Haouz has been traversed, for twenty years, throughout its length, by a canal which not only does not work, but which must also be maintained if one simply wants to keep the work invested. In the spring of 1974, studies will recommend a transfer of water from Lakhdar – Tessaout to central Haouz using the Rocade Canal.
h – The Jaids
Etymologically the faïd (Jayd) is an overflow, an anarchic runoff of water not collected by individual thalwegs. We are talking about groundwater flow. In reality, the topographic surface of natural terrain – its lithology too – does not allow water to flow in a blade, the circulation of water is always linear. But in the faïds. The hierarchy of ravines has not been done or not yet done.
On the occasion of spring waves, when one can place oneself receiving the reflection of the sun, facing these flows of faïds, the entire surface of the topographic glacis shimmers and shines, and it is impossible to detect preferential flows of the water.
Also, there are faïde flows along the Dir, between the basins of the large Wadis. From west to east, we can see the northern flank of the Tiourar hills, on the left bank of the Nfis, the glacis of the reliefs of Jbel Sektana and the hills of Oumnast, Dir Tedrara between Rhirhaïa and Ourika. The flank of Jbel Sahl. The side of Adrar bou Assaba, finally the northern slopes of Tasghimout.
We were able to estimate the volume of water flowing on these slopes at the following values:
|Volume 10* m ³/an|
|Adrar bou Assaba •||20||450||40||0,8|
Sources: Office du Haouz, ORMVAH, 1968.
- Not including runoff collected respectively by the Issil, Qejji, Mellah and Tirhizrit Wadis.
The development of the land in the faïd zone has two objectives, the collection of anarchically flowing water to lead it into an irrigation network similar to that of the séguias. and the protection of cultivated plots below uncontrolled overflows.
The device is very simple, and consists, on the sides of hills and glacis, in constructing a channel (mesref) * of less steep slope than that of natural terrain, cutting diagonally the hairy flows so as to collect them, and serve them at a specific point at the bottom of the slope. In the ravines, the flow is broken by small barrages of dry stones, staggered from top to bottom every 2 meters in altitude, so as to spread the flow and make operative, lower, the mesrefs.
These types of development are very old on the northern slope of Jbilète, especially upstream of Bahira, at the level of Seddal Masjoun. We have been able to show on aerial photos that certain measures were compatible with the hydraulic arrangements of the Yaqoubia Almohade for a very long time out of use. But in the Haouz. The layouts of faïds are all recent, their construction is in the memory of all the villagers who use them.
- MOBILIZATION OF GROUNDWATER
The groundwater is exploited by four different processes: by the development of sources, by artificial drains or Khettara, by drawing by means of animal energy, finally by pumping by means of mechanical energy (fuel, electricity).
2.1 – The sources
The outcrop of the water table, in the current state of its exploitation, occurs in the form of springs, largely, in the so-called “sources of OudaTas” of the old Nfis channel (left bank) between the Zaouïa from Sidi Zouine and the Wadi (1184 ha), also in the Tensift Oulja west of the Koudia Tazakourt (567 ha), and occasionally everywhere on the low terraces of the Nfis (102 ha). These are mainly the resurgences of the Nfis which take place on the left bank in its old bed, and the surplus of the aquifer which flows to the northwest of the right bank of the Nfis, downstream of an area still little exhausted by other dewatering procedures. During periods of lower human occupation and less exploitation, the springs irrigated larger lands on the low terraces of the Tensift, and there are still today inhabitants of Ouidane, who remember perfectly the extension of the marshes fed by springs where migratory birds nested. The first Arab geographers and historians, moreover, pointed out the existence of these marshy zones, which one would be very hard to see today on the ground.
Nothing will be said about the use of springs for irrigation, except that they cannot be used without the construction of an accumulation basin to retain water that flows at night, and when too much low flow, they cannot be distributed directly.
The sources and resurgences, which represent a precious perennial flow, are obviously exploited to the maximum. Unfortunately, their topographic situation is generally such that the dominated areas are insufficient to allow full use of the available flows.
This is the case with the Tensift resurgences captured by 25 Seguias or open drains, irrigate only a narrow strip of land (oulja) on the left bank, and of which only 25 million m3/year are used on a contribution of 60 million.
2.2 – The Khettara
The Khettara is a drain from the water table, whose slope is lower than that of the aquifer and that of the natural ground; as a result, the drain eventually outcrops in the open air and can deliver its water downstream, to irrigate gardens. By itself, the aquifer flows slowly to emit along a line which is the trace of its level of equilibrium on the surface of the natural ground, but this natural flow is not concentrated: the drain has the function of creating depression and lateral water collection. The device, in fact, includes several
– Upstream a mostly draining part;
– Downstream, a part having the function of transport
– In the open air, an accumulation basin;
– Downstream of the basin, a distribution network.
The draining part to be fully effective must be located immediately above the less permeable layers *, therefore to radiate it from the draining part is not perfectly waterproof and it loses, along its course, significant volumes of water. Similarly, the conveyor part continues to receive, through the roof and laterally, contributions at the same time as it discharges water through its raft; even if, in the long run, clogging ends up being due to the deposition of fine clays collected upstream. The distinction, therefore, between the two sections of the underground Khettara, should not be overemphasized.
The accumulation basin is often necessary because the flow of Khettara is low: 75% of Khettara has a flow of fewer than 20 1/s, a 93% flow of less than 20 I/s. The flow constitutes only a part of the hand of water in the Haouz a man is accustomed to lead to the undermining a flow of 15 to 20 V. In addition, the Khettara is a channel that flows all the time, at night as by day; it is, therefore, advantageous to store the product for use during only part of the day. The downside of Khettara is that they are “always open veins” that constantly drain and deplete the water, whether you need water or have nothing to do with it (like night or during rainy periods). You can’t seal the Khettara. Hence the need to build very expensive basins to retain water, which considerably increases the price of them ° delivered on the plot.
Hence the need also, to provide a cropping system that makes water profitable all year round: horticulture, arboriculture, fodder, market gardening, solutions adopted in the suburban Jnanate irrigated by Khettara.
ORGANIZATION OF THE SPACE AROUND A KHETTARA
The use of the drain to bring water to the ground surface naturally has a series of consequences for the distribution of space in the area where this technique is used. Upstream of the water outlet, the builders are forced to punctuate the course along the drain, with a series of wells, every 20 to 25 m to evacuate the underground earthworks and allow the aeration of the site during the works. These wells are then necessary, to carry out repair and cleaning visits, underground galleries. The technology of the time did not seem to make it possible to subsequently plug unproductive access excavations while guaranteeing a sufficiently reliable functioning of the drain. Indeed, the catching part must preserve permeable sides and a suitable behavior of the ground under penalty of landslide “.
DEPTH OF THE WATER TABLE AND KHETTARA SAMPLING
Hence the need for frequent repairs and the conservation of outlet well. The main consequence is to scatter the area drained by a considerable number of wells aligned along the course of the drain: that is to say more or less, on the line of greatest slope of natural terrain. Like the average length of a Khettara in the Haouz is 4 kilometers, and the right of way 5 meters apart and on the other side of the drain axis, it is therefore an area of 4 hectares on average which is Res upstream of the water outlet. A maintained Khettara ien producing on average in Haouz 10 liters per second, that is to say a flow likely to irrigate 15 hectares, it is thus at least the quarter of the total surface which is thus occupied in an unproductive way.
Laterally, in the catchment area, the Khettara cannot be contiguous because they would compete in the collection of the water table and consequently, the ratio work/flow would increase without interest for En The traditional standards adopted, and modern measures aites, show that the lateral influence of a Khettara in its captivating part, dominates The same after 50 meters and is almost zero after 100 meters’ “. So, and these are provisions which have always been fairly well respected, drains do not are not less than 200 meters apart – in the zone of intense exploitation of the aquifer south of Marrakech, the ground, seen from the plane, is cut by a series of pustules representing the drainage and inspection wells. The space included, between the drains, the excluded rights-of-way, leaves free to agricultural or pastoral occupation strips of land more than 180 meters wide, oriented in a north-south direction cannot be cultivated, because the circulation of water on the surface is too often difficult to conduct, and dangerous for the functioning of the drains (risk of landslide); however, it represents an advantage in their diet (infiltration of surface water).
In the purely conveying part, the proximity of the drains has little reciprocal influence, especially if they are roughly at the same level and we can observe then that they wander, move away get closer according to local arrangements and property limits.
The consequence of all this is that the use of an underground drain rain, as a means of mobilizing water, cuts up space fairly clearly in three successive zones, along the slope. For an average Khettara, in Haouz, we must admit: strictly in three stepped areas, along the slope. For an average Khettara, in Haouz, we must admit:
_ An upstream, draining area, 3,000 m long and 200 m. of wide (60 hectares) practically reserved, and hardly usable other- is lying;
– An average, transporting area of 1,000 m. long on
20 m. wide (2 hectares) in which the land is very rowdy, but which does not prevent the existence of intermediate gardens, irrigated by upper Khettara;
– A downstream area of 15 hectares of irrigated gardens.
IMPORTANCE AND ECONOMY OF KHETTARA IN THE HAOUZ
Thirteen percent of the Haouz irrigated area is covered by Khettara alone, and almost 20% by Khettara associated with others means of drawing or irrigation – a balance sheet counted 500 Khettara vivid pulling a total flow of 5.059 liters/second from the tablecloth.
Sources: Exploitation of the analog Haouz 11 DRE 1972 model.
Units: Continuous fictitious liters/second.
The Khettara alone extract 69% of the flows passing through the aquifer, but their yield is only 63%, due to losses along the galleries and in the distribution network. They only distribute 44% of the usable flow of the water table.
The Khettara generally have a small flow and the share of Khettara of small flow in total flow is large.
There is a close connection between the depth of the wells, the length of the Khettara and its flow at least at the time of their digging. The work required to dig a Khettara can be measured by the volume of excavated soil. But that will only give a first approach, because a m3 of earth extracted at 30 meters deep requires a greater mobilization of work than a m3 extracted near the surface. It follows that only Khettara are dug, then maintained, and therefore alive after a few centuries, whose flow, the ratio of flow/volume of soil extracted and average depth, are considered satisfactory by users. The long Khettara which are also, of course, the ones with the deepest wells, are the ones that deliver the most.
|Flow ranges 1/s||Names||Total flows|
|1 à||10||377||75,2||1 856||37|
|10 à||20||89||17,8||1 358||27|
Sources : DRE : 11.01.1974
Extract from the classification by debits of Khettara of central Haouz.
Units: continuous fictitious liters/second.
We can, therefore, very roughly, estimate the work required to obtain a unit of flow. Figures are obtained of 300 working days per liter/second for small flows less than 10 1/s, and to 1,000 working days per liter/second for flows greater than 20 1/s. Above 60 liters/second, the number of Khettara is too small for us to be able to retain average data, and each different case does not allow us to derive a distribution law.
Let us take the order of magnitude of 500 working days on average to obtain a sustainable liter/second, that is to say the flow rate considered sufficient to allow the agricultural food reproduction of a household (therefore approximately 1/2 kg first investment wheat, per m3, depreciated over a very long period).
Even, more than for the séguias, the Khettara require to be built a very high coefficient of human work, the technology used being very rudimentary (sape, basket, rope and pulley). But knowledge of the terrain, water circulation and familiarity with underground conditions (hidden dark forces that have just been disturbed) have always reserved these works for particular corporations. Unlike the séguias, one can doubt the use, by the means of the drudgery, of large masses of earth workers on the long Khettara. The digging of a Khettara is more a craft than a big construction site: each has its slope, its profile, its layout, it must be built well after well; one cannot distribute the work all along, after a simple topographic survey, as one does for a Seguia. Repair, revitalization, maintenance, on the other hand can be carried out in the form of large projects.
Modern methods certainly improve the yield of Khettara significantly and streamline maintenance, but the first digging of modern Khettara had to be entrusted to teams of traditional well diggers.
DISTRIBUTION OF KHETTARA
It has long been believed, and written too often, that Khettara was only built in areas where the water table is shallow. In fact, when we compare the depth map of the water table and the Khettara map, there is nothing to conclude that there is any connection between these two figures. The water table in the Haouz is almost everywhere at least 50 m deep, the zone where it is deep is to the south. That which is largely irrigated by roughly perennial surface waters, and, consequently, there is little Khettara there. Areas, where the water table is deep and random gravity irrigation, are irrigated by Khettara. It can, therefore, be said, in short, that traditional irrigators give preference to the séguias system when this guarantees perennial water; in the event that it cannot, whatever the depth of the tablecloth (or almost), Khettara can be dug, and most of the time has been.
From this point of view, there are three spectacular examples: the Khettara of Marrakech, those of Tamcsloht and those of Aghmat. We can indeed say that the first Khettara built were not the smallest, nor the easiest to dig. The first Khettara probably dug in the Haouz around 1071 (JC), known as Agdal 111 in the official nomenclature, has its head wells at 45 and 50 m deep, two catching arms of 1455 m and 2015 m and a transport arm of 4080 m (total 7550 m). Revived in 1934, it produced 45 liters/second. When the Amghariyinc settle in Tamcsloht. They receive by IqtaÇ from Moulay Abdallah al Ghalib bi Allah the saadicn the irrigation sector of a Khettara, on condition of revitalizing it. This Khettara, therefore dries up at the time of the concession and, which was probably dug under the Almohads13. Three centuries before, is perfectly described (location of the head, outlet, number of arms, orientation, etc.) and can be recognized in the Tamrinc of the official nomenclature with head wells from 41 to 38 m. catching arms of 1360 and 1060 m and an evacuation arm of 2855 m (total 5275 m) whose flow in 1950-1955 was 3 liters/second because very poorly maintained.
On the other hand, it is well known that a large number of small Khettara were recently, and are still, dug today, on the low terraces of the Ourika Wadi. already heavily irrigated by surface water.
Once again, functionalism is defeated by the facts, when these are precisely established. Also, the map of the distribution of Khettara does not fail to be difficult to interpret, and we will give here “only an overview.
DEPTH OF THE WATER TABLE AND KHETTARA SAMPLING
We thus see five to six well-defined and very different sets appear, by the depth of the wells, that is to say by the work invested.
Number of Khettara having their head well of
|less than 20 m||
more than 20 m
WHO OWN THE KHETTARA?
The same type of property status observed with regard to the séguias is found for the Khettara. Small Khettara of less than 5 1/s and less than 500 meters, more trenching open pit than underground drains, are often privately owned or habous, either in the Jnanate of Ouidane, or the cone of Ourika or du Zat, or again at the Oudaïa. The medium Khettara are those of great disappeared characters, in joint possession between the descendants who no longer maintain them today, or else properties of the Habous of Zaouïa, Sidi Zouine, Tamesloht and Zaouïa Ben Sassi in particular. Large, high-speed Khettara are owned by the state, including those that the settlers had revitalized and maintained.
Coindivision and the collapse of interlining solidarities reduce the maintenance effort. These are the private Khettara, especially the medium ones, which require a lot of maintenance work, which collapse and dry up and which are replaced by motor pumps (users having more possibilities of acquiring engines by their own cash or through agricultural credit). Small private Khettara, drains and springs have been maintained. The large state Khettara also, for lavish and tourist reasons, and to provide work for a declining corporation and the urban unemployed.
2.3 – Water extraction using animal energy
The economic importance of individual irrigation systems throughout Haouz is undeniably small compared to that of the other systems previously described. However, we do not have data allowing us to know the flow rates provided or the areas they irrigate. These systems, based on drawing from very small wells, were not subject to authorization, none supplying more than 200 m3 of water per day14. We are therefore reduced to hypotheses. The number of these wells is estimated at 1,800 in the Haouz (according to M. THUILLE); if we admit that they irrigate an average of one hectare each at the most, providing it with 5,000 m3 of water per year, we arrive at an instantaneous flow rate close to 300 liters/second. It’s barely a tenth of the flow rate from the Khettara.
There are two main traditional drawing systems that should be described briefly:
– sania15: it’s the local name for noria. A chain, fitted with tin pots, driven by the gear of two kinds of wheels can, driven by a donkey, fetch water up to 10 m and, exceptionally, even deeper.
– the aghror15 uses a rubber or dlo pocket (which also gives its name to the system); using a pulley and a system of ropes pulled by a draft animal, water can be poured into a nearby basin. It can fetch water much deeper, but rarely is it used for depth greater than 15 m. Beyond that, you only use this system when you have to, and only for drinking. Physical conditions limit its use to certain areas, more restricted than those of Khettara and even pumping, due to the very basic technique: it is indeed necessary that the water table is at a depth less than 15 m. but it is only really encountered with a high density, where it does not exceed 8 to 10 m.
However, drawdowns using animal energy are far from having occupied all the areas where they could technically extend, due to historical conditions. If the traditional withdrawals are completely absent in the west of Marrakech, it is because, for the same reasons as the Khettara, there has never been in this zone guarantee of the property, as we will see in the second part of this work; moreover, colonization, in its race to the water table, irreparably ruined the last that existed. To the east of Marrakech, the collective system of Khettara, very old, has always taken precedence over the individual system of withdrawals: large owners and communities have always preferred investments in irrigation systems corresponding to the cohesion of groups, and helping to maintain it. What is curious, is the posterior, diffuse implantation, of individual withdrawals in some of the spaces left free by the Khettara, an indication of progressive development and of a different type, by the very small merchant bourgeoisie and artisanal of Marrakech after Independence.
The most beautiful example is the dismemberment of Mhammdia, property of appanage (gran) of 700 hectares that the owner, a big king fell in disgrace at the end of the protectorate and no longer benefiting from the levies due to his rank, dismembered in 42 plots of fifteen hectares and sold to a series of small people living in Marrakech. The land no longer benefited from the irrigations that the power of the king could obtain in the past. The 42 buyers of this astonishing land reform, each undertook to install a sania to irrigate their plot, and they would have all done so, if the public authorities, in the vein of cooperative experience, had not grouped them and made them co-users of an electric pumping battery. But the extension phenomenon of the sania has nevertheless progressed around it, for four or five years, before being replaced by small equipment, medium power motor pumps (4 CV).
The social importance of water systems is more extensive than their economic role. This is because, unlike other traditional systems, water extraction only accommodates one specific form of exploitation, to the exclusion of all others.
It is only encountered on micro-farms of 1-hectare maximum, an area that it can irritate; if the exploitation is more extensive, only the relatively irrigated area is developed, the sector irrigated by the drawing, which brings us back to the previous case. If the area to be developed is larger, other irrigation systems are used (traditional Khettara, modern pumping) and preferred to the multiplication of water withdrawals.