CHAPTER II
BASIN IRRIGATION
There are two kinds of irrigation in Egypt—basin and perennial irrigation. Basin irrigation is the ancient and historical method of the country. Tradition ascribes its invention to the first King of Egypt, and it is obviously designed to take full advantage of the annual flood. Practically the same as it was 7,000 years ago, it may be seen in Upper Egypt to-day.
The cultivable land from Assouan to the Delta is, with the exception of the Fayoum, that altogether remarkable province, a narrow strip of country, varying in breadth from a few miles to nothing at all, sometimes on both sides of the river, sometimes only on one. Being of deltaic formation, the land is highest near the river, and slopes away towards the desert. As the river flows from south to north, there is, of course, also a general slope of the country in the same direction. Earthen dykes are run at right angles to the river as far as the desert, a dyke parallel to the river and close to its bank connects them, and so a basin is formed, enclosed on the fourth side by the desert. Thus the land is arranged in a series of terraces. Usually these basins are arranged in a series, one basin draining into its neighbour, the last of the series discharging back again into the Nile. Sometimes a second dyke, parallel to the river, divides the lower land near the desert from the higher; sometimes the arrangement is still further complicated by other dykes, making enclosures within the area of the original basin.
The object of the basins is to regulate the supply of the flood-water. Each series of basins has special feeder canals to lead into them. These are shallow, and have their bed about halfway between the high and low level of the Nile. They are therefore dry in the winter and summer, and only run during the flood. The heads of these canals, where they take off from the Nile, remain closed by dams or by masonry regulators till the silt-bearing flood is coming down in sufficient strength. Then about August 10 or 12 the canals are opened and the basins filled. The lowest basins in each series are filled first, then the next lowest, and so on. In a low flood, as in 1877, there is not enough muddy water to go round, and the upper basins get no water at all; such lands are called ‘sharaki,’ and are exempt from taxation. For forty days the flood-water stands on the land, thoroughly soaking it and washing it, and at the same time depositing its fertilizing silt. At the end of that time, through the escape at the lower end of the series, the water is discharged back again into the Nile. But if the flood is a very high one or very slow in abating, the date at which the water can be discharged and the basins dried has to be postponed. Fortunately, this seldom happens; but when it does it has a doubly bad effect. The oversoaking is said to engender worms, and also the ripening of the crops is postponed to an unfavourable season of the year.
Against this particular evil there is no remedy, but since the British occupation a great deal has been done to improve the system of basin irrigation, and prevent a large amount of sharaki even in years of low Nile. These measures consist in arrangements for distributing the ‘red’ water more evenly over the whole system, and not allowing the lower basins only to receive the full benefit, while the higher merely receive ‘white’ water—i.e., water which has already deposited its silt. Further, since any water is better than none, the systems of basins have been so managed, where possible, that the water from an upper system can be drained into a lower one, and thus make up deficiencies, though with water of an inferior quality. More attention has also been paid to the angle at which the feeder canals take off from the Nile, and the slope on which they are laid, so as to provide as much ‘red’ water as possible, while diminishing the amount of silting up. The result of this work is seen in the diminution of the sharaki lands year by year. In 1877 these amounted to nearly 1,000,000 acres, a loss of £1,000,000 in land-tax. During the next ten years the average was 45,000 acres, an annual loss of some £40,000. In 1888 the loss was £300,000, and the Egyptian Government expended £800,000 in remedial works, which have had an extraordinary effect. In 1899, when the Nile was exceptionally low, the sharaki lands amounted to 264,000 acres only, as against nearly 1,000,000 in 1877.
As for the high lands lying immediately between the river and the basin dyke, only eight or nine times in a century does the Nile rise high enough to flood them. They are called ‘berms,’ and are ingeniously irrigated by means of special high-level canals, which, starting from a point above the head of the basin system, or perhaps leading down from an upper system, pass by means of a siphon under the feeder canal. The berms are, of course, also irrigated by lifting water directly from the Nile itself.
There are forty-five systems of basins in Upper Egypt, most of which, and those the largest, are on the left bank. Some of the feeder canals are insignificant, and feed only two or three basins. Others, like the Sohagia Canal, south of Assiout, feed an extensive system, and are real rivers when full. The basins themselves are 5,000 to 15,000 acres in extent, and it can easily be understood that when they are taking in they have an enormous effect in diminishing the pressure of the flood, and, on the other hand, their discharge lengthens it out in the lower reaches of the river, when the level has already fallen very much at Assouan. While the basins are filling in August and September, they absorb about 2,000 cubic metres per second. Besides this, a considerable amount is employed in filling the channel of the Nile itself and its branches. Evaporation, absorption, and direct irrigation, also play their part, and the result is that the discharge of the Nile at Cairo is some 2,500 cubic metres less than it is at Assouan. But during October and November the basins are discharging. The southernmost ones are empty by October 15, those in the neighbourhood of Cairo not till about November 30, or even later. The consequence is that the Nile at Cairo in October is discharging 900 cubic metres per second more than at Assouan, and in November 500 more.
In November, therefore, the visitor to Cairo can still get some idea of what Upper Egypt is like in flood-time. From desert to desert it stretches, one vast lake, divided by a network of dykes, and studded here and there with villages raised on artificial mounds, which year by year rise higher on their own ruins. A greater flood than usual makes terrible havoc in these villages; for the rising water soon crumbles their mud walls, and the whole collapses like a pack of cards. Every mortal thing is living on the dykes, which play the part of roads; only the water-fowl, emerging in thousands from their secluded marshes, spread themselves in security over the wide waters, and here and there an isolated villager may be seen in an ancient palm-wood tub, paddling and baling by turns. The dykes run on the same lines as they have run for centuries, and on them the traveller, on his way to visit the Pyramids of Gizeh or the Tombs of the Kings at Sakkarah, the burial-ground of ancient Memphis, may watch the whole life of Egypt pass and repass in long procession, set as in a frieze. Work in the fields, of course, is at a standstill, but the villages are humming with preparation for the sowing, and alive with flocks of goats and sheep, camels, buffaloes, and asses; even the rats have been forced to the same refuge, and may be seen popping in and out among the roots of the palm-trees.[4] Where one basin drains into another the fisherman spreads his net, and reaps a rich harvest in the rush of the current. At intervals are stationed pickets of grave watchers, squatting patiently alongside large bundles of millet or maize stalks. This is all that remains of the corvée service, and gladly is it borne.
For every villager is interested in the preservation of the dykes, and apart from ordinary accidents this great lake, owing to the swift changes of temperature in the neighbouring desert, is liable to violent storms, which drive great waves against the crumbling dykes, and would soon break them if left alone. The millet stalks are put down to break the force of the waves. Each village omdeh, or headman, is responsible for these arrangements, and he, too, may be met upon the dykes, a picturesque figure in flowing black and white, mounted on an ambling Arab pony, going round to see that all his sentinels are on duty. How near the past is brought, when you enter the tombs and find painted on the walls, or figured out in stone, the same people engaged in the same pursuits, as though Egypt had not been since then for thousands of centuries coveted and seized in turn by so many invading nations! The cultivator of the soil, moulded by the unchanging and imperious demands of the great river, to which he owes his whole subsistence, has retained the customs, and even the features, of those remote forerunners, who are his ancestors in everything, except, perhaps, by descent of blood.