. The future water supply of San Francisco; a report to the Honorable the secretary of the interior and the Advisory board of engineers of the United States army . llmeasurements over the artesian area for sev-eral years past, as shown on Plates 22 and 23,indicates that the average position of the watertable is more than four feet above what it wasat the time of the survey of June 13-17, that during the summer months, when theevaporation is the greatest, it was as much aseight to ten feet higher. A study of the profilesfurther shows that, because of the vast networkof drainage ditche
. The future water supply of San Francisco; a report to the Honorable the secretary of the interior and the Advisory board of engineers of the United States army . llmeasurements over the artesian area for sev-eral years past, as shown on Plates 22 and 23,indicates that the average position of the watertable is more than four feet above what it wasat the time of the survey of June 13-17, that during the summer months, when theevaporation is the greatest, it was as much aseight to ten feet higher. A study of the profilesfurther shows that, because of the vast networkof drainage ditches, this water table rises lessrapidly when within a few inches of the data indicate that the average annual evap-oration, under the present conditions, is as muchas, or more than, the 20 million gallons per daycomputed for the condition indicated from survey. This 20 million gallons per day is suppliedfrom the water product of the catchment areastributary to Livermore Valley, though becauseit has escaped through the atmosphere it has notentered into the measured run-off below of this, the actual amount of water Plate 24. MAP or WITH ONLY NOMINAL DEVELOPMENT BY SIMPLE CANALS AND DITCHES THE ABSORBTIVEGRAVELS OF THE LIVERMORE VALLEY WILL DRINK IN VASTLY MORE WATER THAN AT PRESENT. 72 POROSITY OP GRAVEL BEDS PROVED BY MEASUREMENTS. 73 produced from the square miles of theAlameda System is greater by 20 M. G-. D. thanis indicated by the 23-year, discharge record ofAlameda Creek below Sunol. Therefore, insteadof an average daily run-off of 145 M. G.,as determined in Appendix B, the totalgross water crop of the Alameda System isapproximately 165 M. G. D. The loss of water through evaporation andtranspiration from the saturated area at thewestern end of Livermore Valley estimated toaverage 20 M. 6. D. during the past 23 years,with sufficient storage capacity, can be saved bylowering the water table and sustaining it at alower level. Storage
Size: 1412px × 1770px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade, booksubjectwatersupply, bookyear1912
