OCR Text |
Show need rehabilitation. Texas has no laws governing the development and use of ground water. As a result there is considerable uncontrolled develop- ment along the Pecos River in Texas, some of which is being done for speculation purposes. Conclusions Treatment of the irrigated lands must be directed toward methods that will conserve available water supplies, prevent soil fertility losses, and prevent im- pairment or destruction of adjacent irrigated lands. Limited water supply and scarcity of other lands suitable for irrigation dictate that programs be di- rected toward more efficient use and conservation of irrigation waters. Additional research is needed to determine water requirements of certain crops, permeability of soils, methods of obtaining efficient use of irriga- tion water, and methods of reclaiming waterlogged and alkali areas. A general overhauling of irrigation works and practices in line with findings of irrigation studies is necessary throughout the Rio Grande Basin. This program should include measures such as installa- tion of adequate headgates; relocation and lining of canals and ditches; installation of measuring weirs, of flumes, of siphons, and of drop boxes; leveling of land and reorganization of laterals and runs. The program should provide for reclamation of damaged areas by adequate drainage; reduction of soil and soil fertility losses through efficient use of irrigation -water; and stabilization of supplies of ir- rigation water through adequate storage facilities by main stream storage and by overnight storage ponds. The application of these measures is dependent upon watershed management, which can be ac- celerated only if present Federal and State coopera- tion is expanded. A satisfactory solution of these problems depends upon measures taken to relieve population pressure in depressed areas and to in- crease incomes in those areas enough to maintain satisfactory living levels and carry out needed land improvement measures. 3. Effect of Watershed Management on Stream Flow and Sediment The Problem The place of watershed treatment to reduce floods and sediment damages and Federal responsi- bilities in watershed management programs. 326 The Situation The combination of watershed misuse and cli- mate has resulted in the Rio Grande Basin's becom- ing one of the most critical land use areas in the country. Continuous use of the range did not be- gin until just prior to 1700. Thereafter, Spanish settlement was encouraged by many land grants of various sizes. Beginning about 1860 the cattle industry became important. It was not until after raiding Indian tribes were placed on reservations that the indus- try really began to boom. Herds were greatly in- creased and the area of use was extended to include most of the upper drainage area. The size of the industry in the upper basin is told in part by the following data: Year Number of sheep Number of cattle 1870. 435, 000 1, 517, 000 1, 732, 000 669, 000 14, 000 210, 000 219, 000 212, 000 1890... 1900... 1935. .. The railroad reached into the upper Rio Grande Basin in 1880. This created a demand for forest products for railroad use as well as for settlement. Difficulties of logging in the mountain terrain re- sulted in clearcutting in accessible areas, so that some old forest areas today bear little evidence of their former cover. The creation of "forest re- serves," later national forests, in 1892 and subse- quently, halted devastation in those areas. Today in the Rio Grande, the effects of land misuse are generally evident. There is sufficient plant cover to control erosion within normal and moderate limits on about 25 percent of the water- shed lands in the Rio Grande Basin. On about 35 percent of the lands, accelerated erosion is at an advanced stage. Rapid destruction is in progress on the remaining 40 percent of the land. Preliminary reports of a study by the Department of Agriculture of the erosion in the middle Rio Grande Basin revealed that 48 percent of the area studied is affected by severe surface erosion, occa- sional deep gullies affect some 20 percent of the land, and frequent shallower gullies, 13 percent. On only 5 percent of the watershed are erosion conditions classed as slight. Much of this erosion is on range lands and much of it is due to misuse of the range. In many areas desirable range species |