6. Can the Present Water-supplies of the Mediterranean Littoral be supplemented by Artesian Borings?

The present water-supplies of the Egyptian portion of the Mediterranean littoral, derived mainly from shallow wells dependent on the local rainfall, are neither very abundant nor of very good quality. At one or two of the most important settlements along the coast, such as Matruh and Sollum, attempts have been made to improve the supplies by sinking wells to a considerable depth in situations where it appeared likely that the drainage from the inland plateau would be specially abundant. But these have met with little success; the yield has been found to be very moderate in quantity, and of poor quality owing to dissolved salts. The question has often been raised as to whether very deep borings, carried down right through the Tertiary strata and into the Nubian sandstone, might result in the procuring of an artesian supply of the same excellent water as occurs in the oases. Hitherto it has not been possible to give a definite answer to this question, and geologists have been reluctant to recommend deep borings, which would entail great expense, without feeling some assurance that they would be successful. The depth to the Nubian sandstone is unknown, but is certainly great; and if borings were carried down into the sandstone, it was not known whether the water would rise to anything like the ground-level. From our new map, however, we obtain a very decisive verdict on the matter. The Nubian sandstone, even if reached, would not be found to be charged with artesian water under anything like the pressure that it is in the oases; leakage into the Qattara and other depressions will have depleted the beds of much of the water coming from the south-west, and will have lowered the static head to such an extent, that the water left in the sandstone will have too little pressure to rise far into the bores. Any idea of sinking deep artesian wells along the coast to tap the Nubian sandstone can consequently be definitely abandoned. We are driven to the conclusion that in any attempt to improve the local water-supplies of the littoral settlements, we can count only on local rainfall for our primary source, and we must do our best to collect the run-off before it has had an opportunity to absorb much salt. The Romans evidently understood this when they excavated the large rock-cisterns on the plateau, of which there are hundreds. We cannot do better than imitate their example, and arrange for the collection and storage of a sufficient volume of rainwater as it runs from the rocky surface of the plateau. We may do this by restoring to use the old reservoirs; or we might possibly achieve our end by damming some of the rocky gullies which bring down the run-off from the plateau to the plain. Now that the artesian idea is shown to be out of the question, there is justification for a thorough investigation as to the best method of collecting and conserving the local rainfall.