Auteur: Aures
Date: 2009-04-10 20:26:22
The Influence of Its Geography on the People of the Aures Massif (suite)
Le système d'irrigation en Aurès
Les Auresiens, écrit Procope au 6e siècle, maîtrisent parfaitement les techniques hydrauliques. Ils dévient les cours d'eaux des rivières, par la construction des barrages et des canaux, de la manière qu'ils croient leur être la plus avantageuse et selon l'usage opportun, soit :
- à des fins militaires (Procope décrit la dérivation de la rivière Amigas pour embourber et inonder les troupes byzantines, voici un extrait tiré de: "L'Aurès au VIe siècle, note sur le récit de Procope" in Antiquité africaines, 1980:
« La rivière Amigas descend de l’Aurès et dans les la plaine, arrose La terre selon la volonté des hommes; les indigènes dirigent le flot à l’endroit et au moment le plis utile. On trouve de nombreux canaux entre lesquels se divisent les eaux qui, en les alimentant tous, disparaissent sous le sol pour réapparaître plus loin à la surface et se former à nouveau en rivière. Ces dispositifs intéressent la plus grande partie de la plaine et donnent aux habitants le moyen en plaçant ou en enlevant des barrages de terre devant les canaux, de faire des eaux de la rivière l’usage qu’il veulent. A cette occasion ils fermèrent tous les canaux et inondèrent le camp des Romains » )
- ou à des fins agricoles ( Voy. dans " Guerre des Vandales " sa description et son admiration pour la prospérité de la culture auresienne animée par des techniques d'irrigations les plus élaborées du 6e siècle:
« ..le mont Aurasios …est assez difficile à gravir, mais qu'une fois parvenu au sommet, on se trouve sur un plateau admirable, sillonné par une foule de sources servant de berceau à des rivières et revêtu d'une merveilleuse quantité d'arbres fruitiers. Toute espèce de céréales et de fruits …. » et «..Prairies luxuriantes, jardins garnis d'arbres, arômes de toute espèce.." etc.. )
C'est ce dernier point, le système d'irrigation en Aurès, que M. W.Hilton-Simpson explore dans cette 3e partie de sa conférence, c'est-à-dire :
- Les barrages
- Les canaux d'irrigations,
- Le partage des eaux.
- La clepsydre aurèsienne ou water-clock (pour remonter à l'origine de l'horloge utilisée chez les Ah Frah de Ain Zaatout, l'auteur la compare avec plusieurs modèles provenant de : Tolga, Maroc, Tunisie - eg la description de l'horloge de Tozer par al-Bekri au 11e siècle- et d'autres pays)
Bonne lecture
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THE INFLUENCE OF ITS GEOGRAPHY ON THE PEOPLE OF THE AURES MASSIF, ALGERIA (Suite)
-III-
In order to stock their granaries the Shawiya cultivate every possible foot of land in their narrow valleys, and the irrigation of their fields has led to the continuance in use in some villages of a primitive type of water-clock for apportioning the limited supply of water available. The system of irrigation employed in the Aures and in such of the oases at the foot of the hills as are watered by more or less perennial streams is simple.
The stream is tapped by means of barrages, or lines of boulders placed obliquely across the watercourse, so that a portion of the stream is deflected into narrow artificial channels, known in Algeria as saqiyas, which conduct the water through the area to be irrigated. The main saqiyas, after supplying branch channels, each watering a group of gardens, discharge their residue of water into the river. This system has been developed until each group of gardens contains a network of miniature canals carried across depressions, and sometimes, as at Beni Suiq in the south-western corner of the massif, across their parent river, in wooden aqueducts often made of the hollowed stems of date-palms. These saqiyas, which are simply dug in the soil without reinforcement of their sides, require constant surveillance to counteract the silting which occurs in them after heavy rain has fallen or snow has melted on the watershed of the Aures; in some districts, therefore, an official is placed in charge of each branch saqiya, whose duty it is to exercise this surveillance and to call upon the riparian owners to make good such damage as it occurs, each landed proprietor being also responsible for the upkeep of a proportion of the barrage in the river whence he indirectly obtains his water-supply.
The construction of a new saqiya, now the care of the French, appears formerly to have been undertaken by some important chief or wealthy native who received as much as two-thirds of the palms in the newly irrigated area as a reward of his outlay and initiative.
As we have seen already, the main streams of the Aures flow southwards from the watershed in the north of the massif to lose themselves in the desert; upon the quantity of water allowed to come out of the hills, therefore, oases such as Sidi 'Oqba and Zribat el Wad on the edge of the desert depend for the production of the dates necessary for the subsistence of many nomad tribes.
Nowadays this amount is controlled by the French, but before their arrival any village of the hills had the right to as much water as its people cared to use regardless of the requirements of their neighbours lower down the river's course, provided that they allowed such water as they did not make use of to return to the parent stream.
Messieurs Hanoteau and Letourneux (' La Kabylie,' 2, 25 I) expressly state that this right was held also by the Berbers of the coastal mountains, and Colonel Lartigue (' L'Aurès,' pp. 438,439, and 445) shows that the Shawiya were in the habit of exercising it. It is evident, therefore, that disputes arising from the vital question of water-supply must have been frequent and probably sanguinary, not only between the Berbers of the hills and the nomad Arabs of the desert, but also between neighbouring Shawiya settlements, and would also have disturbed the peace of individual villages had not the clepsydra or water-clock of ancient times been kept in use to apportion its division.
When the day arrives on which the waters of a main channel are to be turned into a given one of its branch saqiyas (an operation performed without the aid of gates by merely blocking the main channel with earth and cutting an outlet in its side to connect it with the branch) owners of the gardens watered by the latter repair to a point overlooking their land, bearing with them the water-clock by means of which their periods of irrigation are to be timed.
The quantity of water to which each is entitled varies, for it is purchased, apart from the purchase of his land, by each individual farmer, who leaves it as he desires at his death and who may lend or sell any or all of his period of irrigation as he wishes. From 120 to 150 francs for one hour's uninterrupted flow of a branch saqiya every twenty days in perpetuity was stated in 1920 to be the price of irrigation at Beni Ferah.
As the side of the saqiya is cut to admit the water to the first garden to be irrigated, the water-clock, a small bowl of copper or zinc perforated in the centre of its bottom by a minute hole, is carefully placed upon the surface of a pail or earthen jar of water in which it automatically sinks as water enters through the hole. Each owner of land is entitled to so many sinkings of the clock, rather than to any definite number of hours or minutes of irrigation; the clock, therefore, is refloated the moment it sinks, and a pebble is placed on the ground by the individual manipulating the clock to indicate that the farmer has received his first sinking, an additional pebble being added to record his score each time the clock is refloated. Meantime a workman, who has been regulating the flow of the water over the garden or field, which is usually subdivided into rectangular patches by means of very small banks of earth to assist him in his task, is ready on the instant to stanch the rush of water from the saqiya when the owners beside the clock shout to him that his period is at an end; the water is then at once admitted to the next garden to be irrigated.
This division of water, carried out in the presence of the owners concerned and usually of a member of the village council, seems to be considered as equitable by the Shawiya. The clock itself is usually the property of the village council, and so is regarded as the legal measure.
The official bowls appear to sink once in fifteen minutes, those I tried being fairly accurate; but there are in existence a number of privately owned clocks, used unofficially between friends, the time of whose sinking varies. Thus the bowl I collected, now in the Pitt-Rivers Museum, sinks once in about ten minutes, while a specimen from Tolqa on the edge of the desert, collected by Mr. W. J. Harding-King, who has most kindly supplied me with very full notes upon it, varied in its time of sinking from four minutes nine seconds to four minutes four seconds in a series of nine tests, excluding the first test, in which, the clock being dry, the time was about twenty seconds longer.
Mr. Harding-King's clock differs in form from the one I collected. My specimen, which I experienced great difficulty in obtaining, consists of a circular bowl of hammered copper; its side about 1 millimetre thick, its diameter 5 7/8 inches at the lip and 6 inches at the bottom, which is slightly convex, the depth of the vessel being 2 1/8 inches at the side and 2 ¼ inches at the centre. It weighs 16 ounces.
Mr. Harding-King tells me that his specimen closely resembles my own in size and shape, save that its diameter is slightly larger at the bottom than at the top, and that its bottom is slightly more convex than that of my specimen. Both specimens are made of copper of the same thickness, and the bottoms and sides of both appear to be similarly joined by dovetailed edges. Some of the, dovetails in the Tolqa specimen, however, appear to consist of separate pieces of copper distinct from both bottom and side.
The perforation for the inlet of water in the Tolqa clock (3,5 mm. diameter) is greater than in my Beni Ferah example (1 mm. diameter), and Mr. Harding-King's bowl is fitted on the inside with a vertical tube, some 3/4 inch in height and 3/16 inch in diameter, which is fixed to the bottom of the bowl, and is intended, as Mr. Harding-King has stated in the Geographical Journal, vol. 50, p. 361, to regulate the flow of the incoming water. It is in this tube that the greatest difference between our clocks is to be found, and, although a native once attempted to describe to me a clock fitted with a tube, I was unable to follow his vague description, and I have found no such clock myself
With the exception of these two clocks, I have heard of but one other water-clock of the sinking type from North Africa, a type to be found in India, Burma, and Ceylon. Mr. Budgett Meakin gives a brief reference to this type in his work on 'The Moors ' (p. 403), and he also alludes to a Moor who manufactured water-clocks at Toledo for astronomical calculations in his 'Life in Morocco ' (p. 374).
A different type of clepsydra, however, has been reported from North Africa, namely, one in which the bowl is filled and allowed to empty upon the principle of an hour-glass. James Richardson (' Travels in the Great Desert of Sahara,' I, p. 185) noted an earthenware specimen at Ghadames in Fezzan, also used in connection with irrigation; Berthelon and Chantre report an evacuating clock, still known by a Greek name " cadous" (κάδος) from Qabes in Southern Tunis; while El Bekri in the eleventh century found this type, then known as "cadès" at Tozer, some120 miles to the west of Qabes. It seems remarkable that the two types of water-clock should be found in such comparatively close proximity to one another, for although Sir Everard im Thurn informs me that he has seen and collected a specimen in Ceylon, used alternately as an evacuating and sinking clock, Mr. Harding-King's specimen could certainly not have been so used.
From such scanty evidence as I have as yet been able to collect it is difficult to trace the origin of the Beni Ferah clock unless we consider that the fairly numerous remains, some of them in use to-day, of rock-hewn Roman "saqiyas" to be found in the Aures and, as in the gorge of El Qantara, in the neighbourhood of the massif, may indicate that the water-clock was used when these were new to apportion the flow of their waters as it is at Beni Ferah and elsewhere today.
(à suivre)
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