76 



THE IKRIGATION AGE. 



CAN THE UPLANDS BE IRRIGATED ? 



EDITOR PRICE, OF THE STERLING, COLORADO DEMOCRAT, 

 THINKS THEY MAY. 



For the benefit of those who have made no study 

 of the question of upland irrigation and of the water 

 which may be supplied for that purpose by storm drain- 

 age, we submit the following facts: 



The amount of precipitation in the arid region, 

 mainly rainfall, is sufficient to raise good crops every 

 year if it were properly distributed throughout the 

 season and wholly used for moistening the soil. This 

 is easily demonstrated. Of one and one-quarter inches 

 of rainfall, about one-fourth of an inch seeps into the 

 soil and one inch runs off in the mass of storm drainage, 

 following the declination of the land surface to the 

 lowest available point, usually a large depression, where 

 a temporary lake is formed, or the head of a stream 

 by which it is mainly carried down to the great rivers 

 and thence to the gulf. Allowing that four-fifths of 

 the water which falls is thus carried off and its use 

 lost to the land on which it is precipitated, and that 

 really only one-fifth of that precipitation is left for 

 crop growth, since the uplands have produced on an 

 average more than one-fifth of a crop ever since the 



KOM OMBO TEMPLE. 

 South Sil sileh On East Bank of Nile. 



settlement of the country, and have always produced 

 a full crop when the moisture was sufficient, it fol- 

 lows that if a good proportion of the four-fifths of 

 the moisture which is carried off in the storm drain- 

 age could be retained on the land and applied to 

 its crops the arid region would be made to blossom 

 as the rose. While it is not possible to distribute 

 water evenly over our uplands, because of the rolling 

 surface of the country, it is possible by constructing 

 dams in the line of drainage to arrest the outflow and 

 make artificial lakes from which the land below them 

 could be irrigated. 



Computing the present loss of moisture by storm 

 drainage to be four-fifths of the precipitation and ac- 

 cepting the present estimate of total precipitation of 

 fourteen inches as correct, we figure an annual loss of 

 moisture in this dry climate of about eleven inches, at 

 least nine inches of which, or more than three times the 

 amount of storm moisture now appropriated by the 

 soil, could be retained on the uplands by artificial 

 means, and applied to the purposes of irrigation. 



Properly applied there can be no reasonable doubt 



that nine inches of moisture would raise the annual 

 crop average of these uplands to a very profitable point, 

 for less moisture is required by crops in this region than 

 in one of greater humidity. 



To be radically conservative, suppose that only 

 six inches of the annual precipitation is wasted by 

 storm drainage. The net result of water wastage for 



THE ISLAND OF PHILAE. 



Two Miles South of the Assuan Dam, Looking East from West 

 Bank of Nile. 



each acre would be 21,280 cubic feet or 490,000,000 

 cubic feet of water for each township annually. This 

 would fill a reservoir four and one-half miles long, 

 1,000 feet wide and twenty feet deep. Such a body of 

 waier would irrigate, after three or four initial years, 

 10,000 acres of land or a little less than half a town- 

 ship. It would not be desirable to construct one great 

 reservoir in each township because a number of smaller 

 ones would he nearer to the land and less expensive, 



LOOKING NORTH FROM THE ISLAND OF PHILAE. 

 2 Miles South of Assuan Dam. 



avoiding long laterals and consequent seepage, and 

 evaporation, thus insuring greater efficiency of service. 

 The average cost per township of such a system of 

 reservoirs would be in the neighborhood of $30,000, if 

 the work were done by the most economical and ad- 

 vantageous methods, while the increase in annual profits 

 arising from the servient lands would be the same 



