in the incoming waters at Nub, but rather from the lowering of the water level below the degree sufficient to flood the banks of the Nile, or in other words, to introduce it into the canals feeding the basin areas.

What was the case, all means were taken to prevent this by extending these canals and raising their level to the highest points on the river above before.

And in the early part of the last century, a great change occurred.

Abbas Pasha introduced the current system of converting the left bank from basin irrigation to summer irrigation, and thus it became possible for the areas covered by this system to produce two crops per year, approximately, instead of the single crop that was the result of the old system. And because of this change, the need became more pressing than ever for complete control of the Nile water and the establishment of artificial barrages, by means of which it would be possible at any time of the year to deliver water to the required level with precision to fill the canals.

It is noteworthy that irrigation is not uniform in its efficiency throughout the country, and that the cultivated areas do not require in every place the same amount of water per feddan. The reasons for this are mainly due to the difference in climate and to the fact that the regions in Upper Egypt are almost entirely limited to the basin irrigation system to this day.

If we assume that there will be no expansion in the scope of agriculture in the future, which is not inconceivable, we find that the required water quantities and their distribution throughout the year over the cultivated areas will be subject to change according to the gradual conversion of the remaining basin lands in Upper Egypt from their current system to the summer irrigation system. Most of them will be converted according to the system previously followed in this region and will be irrigated with ease either by releasing all the necessary water for them from the existing barrages or by releasing some of it from these barrages and the rest from . And the summer water needed for their irrigation will be easily obtained from lifting machines established for this purpose.

million cubic meters, on average. Experiments show that the lands of the Egyptian country require at present about...

100, approximately 141 million cubic meters of water per year for their crops. The amount that reached Aswan in 1918 was 1 million cubic meters of water. In that year, the flood was exceptionally low. It will be clear that this amount of water, which is the least that has been measured so far, was more than sufficient to meet all actual demands if it had been distributed throughout the year in a manner consistent with agricultural needs. However, the distribution was so irregular that water was discharged into the sea without account during one period, and a shortage occurred during another period.

This disparity in distribution can be greatly reduced by appropriate engineering works, but it is impossible to prevent it entirely due to the violent rush of the flood coming from the Blue Nile, saturated with silt.

Refer to the following table for the details: Table Required quantities for basin irrigation (billions of cubic meters) -4s 1 Required water quantities | 143 Incoming water | Required water for basin irrigation River | without restriction From July to December | and to to From January to June | Basin irrigation | in the year ... ... ..., ... and and And if there were no Aswan reservoir, the actual water volumes would be more than those shown in the table.

million cubic meters in the period from July to December, and less than that from - This amount in the period from January to July 1 0 This is shown here. And accordingly, the other figures in this table have been increased. This amount has been increased from 100,000, which is a very recent matter.