The distress of his subjects under these circumstances seems to have drawn the thoughts of “the good Amenemhat” to the devising of some system which should effectually remedy these evils, by preventing their occurrence.  In all countries where the supply of water is liable to be deficient, it is of the utmost importance to utilize to the full that amount of the life-giving fluid, be it more or be it less, which the bounty of nature furnishes.  Rarely, indeed, is nature absolutely a niggard.  Mostly she gives far more than is needed, but the improvidence or the apathy of man allows her gifts to run to waste.  Careful and provident husbanding of her store will generally make it suffice for all man’s needs and requirements.  Sometimes this has been effected in a thirsty land by conducting all the rills and brooks that flow from the highlands or hills into subterranean conduits, where they are shielded from the sun’s rays, and prolonging these ducts for miles upon miles, till every drop of the precious fluid has been utilized for irrigation.  Such is the kareez or kanat system of Persia.  In other places vast efforts have been made to detain the abundant supply of rain which nature commonly provides in the spring of the year, to store it, and prevent it from flowing off down the river-courses to the sea, where it is absolutely lost.  For this purpose, either huge reservoirs must be constructed by the hand of man, or else advantage must be taken of some facility which nature offers for storing the water in convenient situations.  Valleys may be blocked by massive dams, and millions of gallons thus imprisoned for future use, as is done in many parts of the North of England, but for manufacturing and not for irrigation purposes.  Or naturally land-locked basins may be found, and the overflow of streams at their flood-time turned into them and arrested, to be made use of later in the year.

In Egypt the one and only valley was that of the Nile, and the one and only stream that which had formed it, and flowed along it, at a lower or higher level, ceaselessly.  It might perhaps have been possible for Egyptian engineering skill to have blocked the valley at Silsilis, or at the Gebelein, and to have thus turned Upper Egypt into a huge reservoir always full, and always capable of supplying Lower Egypt with enough water to eke out a deficient inundation.  But this could only have been done by an enormous work, very difficult to construct, and at the sacrifice of several hundred square miles of fertile territory, thickly inhabited, which would have been covered permanently by the artificial lake.  Moreover, the Egyptians would have known that such an embankment can under no circumstances be absolutely secure, and may have foreseen that its rupture would spread destruction over the whole of the lower country.  Amenemhat, at any rate, did not venture to adopt so bold a design.  He sought for a natural depression, and found one in the Libyan range of hills to the west of the Nile