When the level of Lake Mœris was kept up to levels above R.L. 17·50, the regulator at Hawârah near the Labyrinth, which I have supposed controlled the entry of the water into the lake, would have admitted the flood waters freely until the lake rose to the maximum allowable, say R.L. 22·00. If then closed, and supposing the Nile levels to have been 2 metres lower then than now, the regulator would probably have been subjected to a head of about 3 metres as a maximum, but afterwards when Lake Mœris ceased its functions and the lake fell to low levels, the regulator would have had to hold up a head of water equal to the depth of water on its floor, in order to exclude the water from the lake. The right and left side channels would have taken in water from above the regulator for irrigating the reclaimed tracts. The drainage of the irrigated areas would have commenced to form drainage channels, the right drainage following the bed of the original inflow channel into Lake Mœris. As the lake level continued to fall, the drains would have scoured themselves out to lower levels, and cut back. The canals too would then have breached into the deepening ravines.
Plate XXV.
CROSS SECTION OF THE ENTRANCE VALLEY TO THE FAYÛM AT THE OLD BAHR WARDAN MOUTH, 3 KILOMETRES ABOVE HAWÂRAT-EL-MAQTA.
CROSS SECTION OF RAVINE BEHIND HAWÂRAT-EL-MAQTA.
On the opposite sides of the ravine and in face of the village of Hawârat-el-Maqta, during one of my inspections, I came across the remains of two ancient canals, shown on the sketch map, [Plate XXVI.] Starting from the present edge of the ravine are two old canals, clearly distinguishable as such by the existing banks, which are of considerable height. In the angle between the two are the remains of an ancient town, and fragments of granite pillars. One of these fragments was part of the shaft of a large pillar of the clustered-stalk design.
Both these canals, after a few hundred yards, lose themselves in broken ground sloping down and tailing into the main ravine.
Probably the left canal was the first made, and, when it breached into the ravine on its left, the right canal was made to take its place, which in its turn also breached and found its way into the ravine. The take-off was then shifted farther up the Bahr Yûsuf to the position of the present head of the Bahr Sêlah. The dotted lines show the supposed continuations of the two old canals. To feed them, either the ravine must have been dammed below their present take-off from it, or else they must have been continued across the head of the ravine to the banks of the Bahr Yûsuf. The fact that the second diversion diverges from the old canal just where it leaves the ravine, suggests the former alternative, but more probably this was made the point of departure from the first channel so as to utilise the banks, which already existed, for crossing the ravine and avoid the necessity for making a new crossing.
Joined on to the breached end of the left canal there exist some curious vestiges of irrigation works, which have failed. It appears that there was originally an earth dam A B joining the banks of one or other of these two old canals with a point in the direction of or across the ravine. In the line of this bank where the height was greatest, was a thick masonry wall, now known as “Hêt Rozma.” This wall is made of brick and rubble stone of a very inferior quality, built in mortar made of lime and mud; it is 90 metres in length, 5 metres thick, and 6·70 metres high. (The top of this wall is at R.L. 21·35.) The bare end of the wall is evidently the original masonry end, as it was built, no part of the wall having been carried away when the bank, which must have joined its outer end, disappeared. The bank, of which this wall formed the centre, evidently breached and scoured out a hole, marked by the pool C below the breach. This breach was repaired by adding an inclined wall D E to the Hêt Rozma, continued by an earth bank E F to the bank of the old left canal. Again another bank G F seems to have been formed above this, and to have breached. The violent action of the water is shown by the circular hollow H, which has been scooped out of the level ground upstream of this breach.