The weirs were constructed not a moment too soon. It so happened that the summer supply of 1900 was lower than in any previous year of which records have been kept. In 1889 the river sank to a level of ·60 metre below zero on the Assouan gauge. In 1878 it fell to ·71 metre below zero, and this was the lowest known before the summer of 1900. But on three days in that year, May 15, 16, and 26, the river fell to a level of ·91 metre below zero. The position was aggravated by the extension of summer cultivation. The total extent of summer crops had risen still further to over 1,700,000 acres.
To save the valuable cotton crop was the earnest preoccupation of the Irrigation Department. They were able by the most strenuous efforts, not merely to save the crop, but so to treat it that it gave a yield which, only a few years before, would have been considered perfectly impossible even in a good year. But all their efforts would have been in vain had it not been possible, thanks to the new weirs, to raise the level of the water upstream of the Barrage to an extent which would have been exceedingly dangerous without their assistance, and so to take full advantage of the rising flood. The mere enumeration of the special measures which were put into force gives a very good idea of the difficult duties which devolve on those who control the water in Egypt:
1. Earthen dams were constructed in both branches of the river to prevent the inrush of salt water from the sea.
2. Special programmes were laid down for ‘rotations’ on the canals.
The system of rotations, which was introduced from India, is that the land-owners are only allowed to pump water on to their lands at certain intervals. There are several advantages in this. The water is economized, and as it can thereby be kept at a lower level in the canals, there is less danger of the soil becoming deteriorated by excessive saturation. The pumps are allowed to work for a certain period, according to the district, and then an interval is prescribed, until the expiration of which they are not allowed to work again. In 1900 the pumps were allowed to work for a period of six days at a time, and at first twelve days was the interval until the next pumping. But as the summer wore on, and the river continued to fall, the interval was gradually extended to twenty-two days—a very severe measure indeed.
3. All land-owners were warned not to sow rice.
4. They were also forbidden to sow maize until a date should be announced.
5. Special pumping arrangements were made.
6. There was more than usually careful regulation at the heads of the canals above the Barrage, so as to insure a proper distribution of the water available to all the provinces.
7. A special staff was appointed to see that all these regulations were carried out.