An Egyptian oasis

by H. J. L. Beadnell

One frequently hears it stated that the oases were far more thickly populated and better watered in olden times than at the present day. This belief is based on the existence in many parts of the depression of extensive remains of temples, forts, and villages, on the widespread traces of formerly cultivated lands, and on the abundance of sanded-up wells. It must not, however, be forgotten that the remains in question belong to successive generations, and that there is as yet no evidence to enable us to determine how much of the land, or how many of the wells, were in use at one and the same time. The evidence is, however, sufficiently pronounced to justify the conclusion that under the Romans the oasis of Kharga was far more flourishing than in modern times, a large part of the population being engaged, not in agriculture, but in mining, boring, and in the excavation of subterranean aqueducts.

LANDS UNDER RECLAMATION AT BORE NO. 39.

We have heard the most diverse and dogmatic opinions as to the feasibility of restoring the oases to their supposed former prosperity. For my part, I do not think that there is the slightest doubt that the total discharge of water could be very much increased, though to what extent it is impossible to say with the information at present available. One must consider the vast areas under which the water-bearing sandstones are known to extend, and the comparatively small extent of country over which the existing wells occur; that as yet the deepest bores have only penetrated the water-bearing beds to a depth of 122 metres; that the existing total discharge is mostly made up of insignificant flows from a great number of ancient and comparatively shallow wells, which for centuries have been subject to gradual decay; that so far as observed the flows increase in volume as deeper beds are struck; and that it might be possible to use artificial means of lifting the water to the surface, especially in districts lying above the level to which the artesian water will rise unaided. The extent to which the water-supply could be profitably augmented is, however, quite another question, and one depending on a great number of at present indeterminable factors.

According to local tradition, the waters of the Kharga wells come directly from the Nile through subterranean passages under the intervening plateaux, and the experience of an Arab trader is frequently related in support of this idea. The Bedawi in question, while engaged in filling his water-skins on the banks of the Nile, preparatory to setting out across the desert to the oasis, let fall his ‘tarbush,’ which was speedily engulfed in an eddy of the river. Although much annoyed at the time, our friend soon forgot the incident, until a few days later, when he was refreshing himself after his journey at a well in the neighbourhood of Beris, the identical piece of head-gear was borne up from its depths!

Mr. Patterson, whose knowledge of the folklore of the inhabitants is unique, recently related to me the following characteristic story: The natives of Beris, as the result of opening a long sanded-up well, obtained a very large flow of water. So terrified were they at the magnitude of the discharge—imagining, indeed, that they had tapped the Nile—that a deputation was hastily despatched to the Governor of Assiut, with profuse apologies for the damage done to the river. Needless to say, the Governor was somewhat taken aback, but realizing the solemnity of the mission, magnanimously informed its members that the waters of the Nile were so abundant that they might without fear take all they required.

At present any attempt to explain the origin of the artesian waters of the oases must be regarded as little better than speculation. More information is required concerning the geology of the country to the south of the oases, and as to the relative levels of the oases-depressions and the different parts of the Nile Valley and Libyan Desert, as far south as the more elevated regions of Kordofan, Darfur, and Tibesti. Little has been written on this subject, but the source generally assigned appears to have been Darfur. Possible sources of origin lie in the rainy districts of the Sudan, in the mountainous region of Abyssinia, in the great swamps of the Upper Nile, in the Nile River itself, and in past accumulations of water absorbed from the extensive lakes which covered parts of the country in the pluvial period which preceded the existing desert conditions.

In the present state of our knowledge I am personally inclined to agree with those who regard the Nile River as a present source of supply. It is known to flow for a considerable part of its course through a valley cut out in the Nubian Sandstone, and it is believed to lose an appreciable volume of water into that sandstone, though the exact amount has not been determined. Mr. J. I. Craig, of the Egyptian Survey, has estimated that at low Nile as much as 6,000 cubic metres of water (1,320,000 gallons) per minute drains back into the river from the sandstones on either side of the reach between Khartum and Wadi Halfa, and, as Captain Lyons remarks, this indicates that there is considerable percolation into the sandstones from the river when in flood.[10]

There is one point of the greatest importance to which we should like to draw attention, as it is generally entirely overlooked. The stores of water in the sandstones may represent the accumulations of hundreds and thousands of years, and the conditions to which the beds formerly owed their sources of supply may at the present time have become materially altered. It is quite conceivable that it may have required centuries or thousands of years to saturate the huge block of sandstone underlying the Libyan Desert, and even were the original sources of supply entirely cut off at any particular time, the effect on a few hundred bores, discharging only 50,000 cubic metres a day, would not necessarily be appreciable in one, or even five, centuries.

The total annual discharge of the whole of the wells of Kharga Oasis is barely equal in volume to the water which can be held by saturated beds underlying 1 square kilometre of surface, assuming the sandstone to be only 122 metres thick; that is to say, it would take between 3,000 and 4,000 years for the existing wells to discharge the water held by the beds underlying the depression alone, without considering the vast surrounding desert areas, where there is no reason to doubt that the water-tables are equally well developed. It must not, however, for a moment be supposed that bores would continue to discharge until the sandstones immediately surrounding them were completely depleted of water; they would, in all probability, pass into a sub-artesian condition in a very short time were the sandstones not replenished from more outlying districts.