Egyptian irrigation, Volume 2 (Google eBook)

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E. & F. N. Spon, ltd, 1913 - Irrigation - 883 pages
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Page 531 - ... fall of the river per mile." It has no reference to the slope of the bottom of the river. One end of the slope is unalterably fixed by the Gulf of Mexico. Other points in its line may be lowered or elevated to a certain extent by natural or artificial causes. The force which produces the current is the fall of the water from a higher to a lower level, and the slope is an indication of the amount of this force. Other conditions being the same, the steeper the slope the more rapid will be the current....
Page 531 - The bend of Fort St. Philip is a notable instance. Great differences in the width of the flood channel constitute the real cause of the destructive caving of the banks. These induce great irregularities in the slope of the flood-line and consequently great changes in current velocity, by which the scouring and depositing action are alternately brought into very active operation. The whole river below Red River proves this. Caving banks are much less frequent there than above, because the flood width...
Page 673 - ... system, applied to suitable lands, is more profitable than the basin system, but depends on the summer supply of the Nile, which is both limited and irregular in quantity. Basin irrigation depends on the flood, which is practically unlimited, and very fairly regular in quantity. In Mehemit Ali's time the great preoccupation of the Government was the pressing on of the cultivation of cotton, and as...
Page 537 - Nile bank had breached spread fast through the village. The villagers rushed out on to the banks with their children, their cattle, and everything they possessed. The confusion was indescribable. A very narrow bank covered with children, buffaloes, poultry, and household furniture.
Page 531 - undercharged " theory of the Delta Survey Report, caving banks are attributed to the direct action of the current against them, by which strata of sand underlying those of clay, etc., are supposed to be washed out. This is not correct. If the water be charged with sediment to its normal supporting capacity, it can not take up more unless the rate of current be increased. Caving banks are caused wholly by the alternations in the velocity of the current. These alternations are...
Page 531 - ... current velocity, by which the scouring and depositing action are alternately brought into very active operation. The whole river below Red River proves this. Caving banks are much less frequent there than above, because the flood width of the river is far more uniform. A correction of the high-water channel by reducing it to an approximate uniformity of width would give uniformity to its slope and current, almost entirely prevent the caving of its banks, and through its present shoals, which...
Page 757 - ... their own cattle, it is otherwise an expensive method, and can only be made to pay by cultivating the more valuable kinds of crops. Moreover, it would seem to be out of favour with those who have had experience of both canal and well water. Mr. Buckley remarks : " The superiority of the rain-water over that of wells is demonstrated by the fact that near the heads of the Punjab canals the cultivators prefer to pay canal rates and to lift the water from the canals rather than to lift it from wells,...
Page 693 - Moeris, will be well able to supply the two remaining milliards of cubic metres of water when working in conjunction with the Assouan Reservoir. The great weakness of this projected lake has lain in the fact that by itself it can give a plentiful discharge in April and May, less in June, and very little in July, and it was for...
Page 700 - It will be an evil day for Egypt if she forgets that ... the lessons which basin irrigation has taught for 7,000 years cannot be unlearned with impunity. The rich muddy water of the Nile flood has been the mainstay of Egypt...
Page 631 - XXV. Un travail que l'on entreprendra un jour sera d'établir des digues qui barrent la branche de Damiette et de Rosette, au Ventre de la Vache. Ce qui, moyennant des batardeaux, permettra de laisser passer successivement toutes les eaux du Nil dans l'est et l'ouest, dès lors de doubler l'inondation.

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