OCR Text |
Show -10- capacity problem but would introduce difficulty in maintaining diversion and bank protection works. The flood dangers in the second need not be described. The third possibility, while harmless at ordinary times, would be the most dangerous in time of flood. In view of uncertainties connected with this situation, it is advisable to make liberal provisions for flood control, and maximum reservoir discharge of 75,000 second-feet with a near maximum flood, such as that of 1884, has been adopted. Flood volumes. In arriving at these volumes for the years of record since 1902, consideration has been given to the loss and temporary storage of water in the channels and by overflow between Boulder Canyon and Yuma. The 1884 flood is known to have been the largest flow, both in rate and seasonable volume, that has occurred in Colorado River since settlements were made along that stream. Estimates for the 1884 flood are based on a gage height at Grand Junction, gage heights at Yuma, detailed newspaper accounts of flood conditions in western Colorado, a flood observation at Lees Ferry, high-water marks in Black Canyon, and reports of conditions at Needles by the Atchison, Topeka & Santa Fe Railroad engineers. Probability theories have been applied to the data with the following results, under conditions of no upstream irrigation: Run-off, in millions of acre-feet in excess of- Occurrence once in- 40^000~~ 50,000 60,000 75,000 100,000 second- second- second- second- second-feet feet feet feet feet 10 years ................ 9 7 6 4 2 50 years ................ 13 10 8 6 4 100 years .............. 14 12 9 7 4 500 years ................ 17 14 10 8 5 1,000 years .......... 18 15 11 8 5 1884 flood.............. 22 20 18 15 12 |
Source |
Original book: [State of Arizona, complainant v. State of California, Palo Verde Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, California, City of San Diego, California, and County of San Diego, California, defendants, United States of America, State of Nevada, State of New Mexico, State of Utah, interveners] : California exhibits. |