Page 57


Page 57
Colorado River problem
Is Part Of,8
Full text
362 ALLISON ON THE COLORADO RIVER PROBLEM streams. These materials form themselves on the bottom of the streams into dunes and anti-dunes and move as such in sand waves down the stream. It is due to the dragging rather than to the suspension faculties of the stream that these types of sands are transported. The first movement begins at a surface velocity of 1.3 ft. per sec. [Fig. 18. PROFILE OF PROPOSED ALL AMERICAN CANAL THROUGH SAND HILLS] From the tabulated data on movement of sand waves,* the following cases are recorded where velocities and sand weights correspond to those of the All-American Canal: In the Mississippi River at Helena, Ark., crests of sand waves moved 17.17 ft. per day with a stream velocity of 3.58 ft. per sec. In the Loire, for corresponding velocities the movement was from 16.4 ft. to 36 ft. per day. Measured by M. Sainjon, in the Loire, under a surface velocity of 1.33 m. per sec., the crests of sand-bars moved from 0.000056 m. per sec. to 0.000087 m. per sec. From the foregoing experiments it is safe to assume that materials of like nature injected into the All-American Canal will be dragged along the bottom of the canal in sand waves under the prevailing velocities of 3 to 4 ft. per sec., a distance of approximately 6,000 ft. per year. Of the materials presumed to have been thrown into the canal by the wind, only one-tenth will be thus scoured from the critical section through the sand-hills, leaving 2,800,000 cu. yd. to be removed with dredges each year. As a matter of fact, even the small proportion that passes through the critical section in sand waves will only be distributed through lower reaches of the canal, as there are no sluiceways available near the sand-hill section. Any neglect in the yearly dredging of the canal or any accumulation of sand deposits in one section will result in a complete blocking of the water supply, unless the Mexican Canal is maintained as a stand-by. The effect will be to demoralize the living conditions of the 50,000 to 60,000 people in the Imperial Valley, who are dependent entirely on the Colorado River for their water supply. Practical Substitute for the All-American Canal.—The outlying lands in the Imperial Valley Basin, including the East and West Mesa and the Coachella Valley, can secure a water supply from the Colorado River. However, this must be attained without overburdening the already too heavily taxed users of water in the Imperial Irrigation District. This can be done in a practical manner and at much less expense than the All-American Canal _______________________________________________________________________________________________________________________________________ * "The Suspension of Solids in Flowing Water", by Elon Huntington Hooker, Transactions, Am. Soc. C. E., Vol. XXXVI (1896), p. 239.

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