OCR Text |
Show 292 REPORT OF THE CHIEF OF ENGINEERS. strength of foliage, along the narrow valleys bordering the river. The mulberry could also doubtless be made to flourish. The unfortunate climate to which this portion of the Southwest is at present treated by the hand of uature is likely to retard its rapid settlement, even if water was plentifully available; still at some future time in the settlement of the West, each cubic foot of the waters of the Colorado is likely to become valuable in agricultural, mining, or other pursuits. The topographical data obtained by Lieutenant Bergland's party, as partially shown by the sketches herewith, (sec Appendix B.) although apparently meager, is yet sullicient to illustrate the route of the party and to locate the principal points referred to in the report. It will all be incorporated in the regular atlas maps covering the regions traversed, to which it will prove a valuable contribution. A sketch of the region south of latitude 37° £0' is here introduced, showing the diversion between the direct coast-drainage and that forming part of the great valley of the Colorado and of the interior basins, those lying in California and Nevada. The total number of square miles shown is 104,300, of which 88,300 square miles approximately belong to California, and 10,000 square miles to Nevada ; 4L',<>00 square miles of this area is a part of the great valley and coast drainage, or 48 2-10 per cent. Of the remaining area about 4.>,7OO square miles, of which less than 2 per cent., is now arable, or could be made arable with all the water available within its limits. Of the amount constituting the coast and valley drainage, allowing that 00 percent, can be made valuable for agricultural purposes, (an amount presumedly largely in excess of what would be found to be true after a rigid examination and survey of these areas.) it appears that of this portion of California south of latitude 37° L'0', only !!JM per cent, can ever, with the best facilities, be made useful for agricultural purposes. The area ill California of a desert character, the H,7no square miles above mentioned, is much larger than the area of the same character in Arizona, the latter having been charged as the acme of the desert of the United States, whereas the Great Colorado plateau and plauteau-ridges about the upper waters of the Salt and Gila Rivers, and the sources of certain minor streams, as the San Pedro and Santa Cruz, are sections that are quite the reverse of deserts. While the southwestern portion of Arizona must always remain sparsely inhabited because of its want of water and stretches of sandy waste, yet the'amount thus withdrawn from all hope of settlement, except at little water-stations, is comparatively less than the desert portion of California lying south of latitude 37° 20' N., as shown by the sketch. This state- tbrough section^ 14,444 cttWie feet per second. Here the velocity throughout the section would bo increased at time of high water, and a largo quantity would llow outside of the section. Stout'a Firry, AeNMfa, August 12, 1H75.-Area of rectum - .r»,?2:5 square feet. Width ^ 4H) feet. Hydraulic radius, or mean depth = 11.KI feet. Mean velocity - :i*/l* fi** jmt second. Discharge = 1h,410.3m cubic feet. High-watermark of ltff I is l?.«»l feet above surface of water at time of observations. Increa.su of area at high water l».?7:>.l. The whole discharge at high water takes place through the section. StipiHtsiug the mean velocity to remain the same as August 12, lefT'i, the increase in discharge would be M.4:?J.7 cubic feet per second; but as in reality there would also \h\ an increase in the velocity, the increase in discharge- would lw somewhat greater than this, but how much greater canuot be determined without direct ex|>crinients. Camp Mokare, A. T., September 2, 1S75.-Area of section _- 4,«W"* square feet. Width !,lib" feet. Mean depth (hydraulic radius) - 4.144 feet. Mean velocity ¦- US*** f«* per second. Discharge = U.tilO.lKi cubic feet per second. High-water mark of W4 above surface of river = 8 f««t. Increase of area of section at high water WwVi.--".' feet, (excluding overflow ou flats.) Increase in discharge through the section would be 34,274 cubic feet, but as a considerable quantity of the bottom beyond the section in then covered with water, this will not represent the total increase. Hero there would l»c but slight increase in the velocity, aa the water has a chance to spread over the bottom-lands, (see plot of section. ) |