摘要:

The American Geophysical Union was established in 1919 as the American Committee of the International Union of Geodesy and Geophysics, and its Executive Committee is the Committee on Geophysics of the National Research Council. The objects of the Union are to promote the study of problems concerned with the figure and physics of the Earth, to initiate and coordinate researches which depend upon international and national cooperation, and to provide for their scientific discussion and publication. In the accomplishment of these objects, the Union is divided into Sections following the plan of organization of the International Union of Geodesy and Geophysics. There are now eight sections, namely, (a) Geodesy, (b) Seismology, (c) Meteorology, (d) Terrestrial Magnetism and Electricity, (e) Oceanography, (f) Volcanology, (g) Hydrology, and (h) Tectonophysics. A Section of Geophysical Chemistry was discontinued May 31, 1924, as the International Union had failed to provide such a Section. The Section of Hydrology was established November 15, 1930—matters pertaining to scientific hydrology referred to the American Geophysical Union had been previously looked after by special committees on Hydrology. The Section of Tectonophysics was established April 9, 1940, for the purpose of promoting and encouraging research of fundamental importance to our knowledge of Earth‐structure not covered in any one of the other Sections of the Un

ISSN:0002-8606    

DOI:10.1029/TR021i001p00003

年代:1940

数据来源: WILEY

摘要:

Perhaps the first reaction to the title of this paper may be “why discuss probability? If that approach in hydrology has not already been discarded, it ought to be.” Certainly the critical attitude toward studies of probability expressed in much recent engineering literature would suggest this conclusion.The following quotation from an article “Possible and probable future floods” by William P. Creager in the November, 1939, issue of Civil Engineering is representative:“About 1914 the theory of probabilities was applied to flood studies; that is, curves were derived indicating by past records on a stream the frequency with which, during a long period, a given flood should be expected. Notwithstanding the fact that periods of record sometimes did not exceed 20 years and very seldom exceeded 30 or 40 years, these probability‐curves were extrapolated to estimate the flood which would be expected during long periods—once in 1,000, 5,000, 10,000 years, etc. Then, according to the judgment of the engineer, the 1,000‐, 5,000‐, or 10,000‐year flood was selected for the design‐cap

ISSN:0002-8606    

DOI:10.1029/TR021i001p00007

年代:1940

数据来源: WILEY

摘要:

The Santa Clara Valley Water Conservation District, comprising the major part of the Santa Clara Valley, was formed for the purpose of harvesting the waste flood‐waters of the surrounding watersheds and of charging these waters into the porous strata beneath the Valley which form the underground reservoir from which the Valley's irrigation and domestic waters are drawn, and which was in an advanced stage of depletion. This situation was brought about by the growth of the fruit and vegetable‐raising industry with its resultant increasing use of irrigation‐water until the yearly draft upon the underground reservoir exceeded the yearly replenishment and a continued decline of water‐levels occurred. Several investigations of the water‐resources of the Valley were made and culminated in the formation of the District, the construction of storage‐ dams and of percolating works, the collection and conveyance by these works of waste‐water to the underground reservoir, and the consequent rising of the Valley's

ISSN:0002-8606    

DOI:10.1029/TR021i001p00013-2

年代:1940

数据来源: WILEY

摘要:

The Santa Clara Valley Water Conservation District includes 138,000 acres of the Santa Clara Valley, California, of which 120,700 acres are cultivated lands, roads, and cities which are watered by approximately 2,000 pumping wells. During the period of deficient rainfall, 1916–1934, prior to Santa Clara Valley water Conservation District's spreading operations, the average water‐level in wells dropped about 108 feet.Attention of those interested in ground‐water conservation has been focussed on this area because of the successful organization of the Santa Clara Valley Water Conservation District, the recovery of water‐level due to water‐spreading operations, the contamination of ground‐water around San Francisco Bay, and the sinking of land‐surface over an area of about 200 square miles, forming a trough‐like depression with maximum lowering in 1937 at San Jo

ISSN:0002-8606    

DOI:10.1029/TR021i001p00023

年代:1940

数据来源: WILEY

摘要:

A precise but easily operated apparatus for testing resistivity of well‐waters has been developed in the Stanford University Hydrologic Laboratory. With it, field‐investigations were made on 20 wells in an area contiguous to the southern part of San Francisco Bay where salt‐water encroachment into the upper gravels has locally contaminated ground‐water supplies.The apparatus consists of a measuring unit operating on 120‐ or 240‐volt, 60‐cycle alternating‐current, or from a 6‐volt storage‐battery, and a cable‐unit with attached electrode‐cell. The electrode‐cell was lowered into wells and resistivity‐measurements were made continuously or at desired depths. Both static and pumping tests were m

ISSN:0002-8606    

DOI:10.1029/TR021i001p00035

年代:1940

数据来源: WILEY

摘要:

Tens of thousands of samples of water have been taken from streams, springs, and wells for chemical analysis, without much use having been made of the results. Unfortunately, the chemists have been little concerned with any engineering interpretation of such analyses and the engineers have had no ready method of interpreting them. Consequently, engineers and agriculturists have usually limited themselves to consideration of only the total dissolved solids, or the total hardness, or possibly the amount of chlorides; the real significance of the analyses has been overlooked.

ISSN:0002-8606    

DOI:10.1029/TR021i001p00046

年代:1940

数据来源: WILEY

摘要:

Though the title of this paper permits a rather general discussion of water‐table problems, the authors intend to review the literature briefly and to give some of their findings in a field‐study of a section of the Sacramento Valley. Besides the abundant data presented in Water‐Supply Papers of the United States Geological Survey, many independent reports and papers bear upon ground‐water tables. Selected highlights from a few of these publications will bring the present discussion into focus.Lee [see 5 of “References” at end of paper], working in Owens Valley, found by using 10‐ foot‐deep “post‐hole” wells dug in clay that “ridges” followed the beds of streams and that “mounds” extended below irrigated fields, whereas the water‐table contours roughly followed the general valley‐contours. Meinzer [6]made a water‐table contour‐map of Silverbow Basin, Montana, by using data from wells ranging from 12 to 119 feet in depth, with water‐levels from two to 89 feet below the surface. Clark [1, 2], studying the Niles Cone and Morgan Hill areas in California and using numerous wells whose water‐levels varied during each season, drew conclusions as to specific yields of the areas. In the Morgan Hill region he chec

ISSN:0002-8606    

DOI:10.1029/TR021i001p00053

年代:1940

数据来源: WILEY

摘要:

This paper presents the results of analyses of ground‐water conditions and water‐supplies underlying lands adjacent to San Joaquin River between Friant and Gravelly Ford Canal and their present utilization and sources of replenishment, based on an intensive field‐investigation initiated in the fall of 1936 and continued through the fall of 1938. The investigation was made under the direction of the Water Project Authority of the State of California, by the state Division of Water Resources, under the provisions of a cooperative contract with the United States Bureau of Reclamation, for the purpose of collecting data to be used in the determination of present rights to the use of San Joaquin River water inhering in lands between Friant and Gravelly Ford Canal, which would be affected by the construction and operation of the Central Valley Project. The field‐investigation included hydrographic, hydrologic, and topographic surveys and the collection and correlation of available data and information appropriate for use in a determination of the extent of present irrigation‐development and sources and amounts of available surface and underground water

ISSN:0002-8606    

DOI:10.1029/TR021i001p00058

年代:1940

数据来源: WILEY

摘要:

The amount of suspended solid material transported by a stream is usually determined by making measurements of sediment‐content and of velocity at many points in the cross‐section and integrating the results. The number of sampling points required will depend upon the degree of accuracy necessary, and, according to O'Brien [see 1 of “References” at end of paper], upon our knowledge of turbulent flow and its relation to sediment‐transportation.The suspended‐load samplers used for these measurements may be divided into two classifications, depending upon the length of the sampling period. One might be called the integrating or continuous sampler, and the other the instantaneous or grab sampler. Turbulent fluctuations cause the sediment‐content at any point in a stream to be continually‐varying; therefore, only an integrated sample, taken over a period of time long enough to get an average concentration, can truly represent the sediment‐content. This integration may be made with a continuous sampler of the suction‐nozzle type, which maintains the same velocity at the entrance as the undisturbed velocity of the stream at that point. (Continuous suction‐nozzle samplers are now being used in the Cooperative Laboratory of the Soil Conservation Service at the California Institute of Technology.) The mean concentration may also be obtained by combining a number of small grab‐samples which show the true instant

ISSN:0002-8606    

DOI:10.1029/TR021i001p00078

年代:1940

数据来源: WILEY

摘要:

In several previous meetings of the South Pacific Division of the Union, various reports concerning the San Dimas Experimental Forest were presented but were not subsequently submitted for publication. The present paper is therefore in the nature of a description of the project and a progress report of accomplishments to date. (Data included in this paper were tabulated and summarized by workers on WPA Project 765‐07‐3‐1.)The San Dimas Experimental Forest is situated on the south front of the San Gabriel Mountains northeast of Glendora, California, within the boundaries of the Angeles National Forest. It has a gross area of approximately 17,000 acres, including the drainage‐basins of Big Dalton and San Dimas Creeks tributary to the San Gabriel River. The Experimental Forest was established in 1933 as a branch of the California Forest ana Range Experiment Station of the United States Forest Service and comprises the principal field‐unit of a comprehensive research program in the field of watershed‐management (forest‐influences) in the California region. The objectives of the research program as it applies to the San Dimas Forest are twofold: (1) To study the influence of the chaparral vegetation, soils, geological structure, and other factors upon the yield of usable water; (2) to develop methods of managing or treating the chaparral watersheds to obtain a maximum yield of usable water with a minimum of dam

ISSN:0002-8606    

DOI:10.1029/TR021i001p00084

年代:1940

数据来源: WILEY