摘要:

Phreatophytes, plants that depend on ground water for their water supply, cover about 15 million acres in the 17 western states, and may waste as much as 20 to 25 million ac ft of water into the atmosphere annually. There are many variable factors that affect the growth and use of water by the plants, but present‐day knowledge of them is limited. The water used by these plants probably represents the largest source of reclaimable water in the arid western United States. Although it appears feasible to salvage a part of this water, methods for doing so have not passed the experimental stage. In Nevada, it is estimated that it would be practical to salvage about 25 pct of the water wasted annually, or about 400,000 ac ft. This would be sufficient to irrigate about 133,000 acres of alfalfa having a crop value of $10,000,00

ISSN:0002-8606    

DOI:10.1029/TR033i001p00057

年代:1952

数据来源: WILEY

摘要:

Before the available water resources of a drainage basin in arid and semiarid regions can be satisfactorily ascertained, careful consideration must be given to the consumptive water requirements of phreatophytes (or water‐loving vegetation) and other types of natural vegetation and agricultural crops. The moisture requirements of natural vegetation are usually satisfied before water becomes available for irrigation and other purposes. Although evapotranspiration (consumptive use) by phreatophytes has been measured at various times and places during the past 40 years, very little data are available in most sections of the United States. This paper presents data on measured evapotranspiration by phreatophytes and describes a method of determining rates of water consumption in areas where no measurements except climatological data are available. Briefly, the procedure is to correlate existing evapotranspiration data with monthly temperature, monthly percentages of yearly daytime hours, and growing period. The coefficients so developed for different kinds of vegetation are used to transpose the evapotranspiration data for a given area to other areas for which only climatological data are availabl

ISSN:0002-8606    

DOI:10.1029/TR033i001p00061

年代:1952

数据来源: WILEY

摘要:

The following is a summary of data obtained in a study of transpiration by phreatophytes in the channels of the Salt and Gila Rivers, between Granite Reef and Gillespie dams, Maricopa County, Arizona. The study was made in the spring of 1950 by the U. S. Geological Survey in cooperation with the Corps of Engineers, United States Army. The kind and amount of phreatophyte growth was mapped in the area covered by a proposed flood‐control channel, 2000 ft wide, extending between the two dams. Most of the mapping was done from the air, using recent aerial photos. Transpiration by the phreatophytes was computed using the results of the mapping combined with water‐use factors developed by experimental work done by the Geological Survey in Safford Valley, Arizona, during 1943 and 1944. Estimates of future phreatophyte use and of the amount of water that might be saved by clearing and maintaining the channel area were based on extensions of water‐level graphs to include the next 50 years, and on the experimental work at Safford. The estimates were as follows: (1) total estimated transpiration from ground water at time of investigation ‐ 29,000 ac ft per year; (2) estimated average transpiration from ground water, within the channel area, during period 1950–1999 (a) without Colorado River water ‐ 22,200 ac ft per year, (b) with Colorado River water in 1960 ‐ 29,900 ac ft per year; (3) estimated average water saving effected by channel clearing, 1950–1999 (a) without Colorado River water ‐ 16,600 ac ft per year, (b) with Colorado River water in 1960 ‐ 22

ISSN:0002-8606    

DOI:10.1029/TR033i001p00066

年代:1952

数据来源: WILEY

摘要:

A point is now being reached in our agricultural planning, especially in the Southwest, that all measures must be considered in extending the limited water supply. The removal of phreatophytes, which annually use enormous quantities of water in a very non‐beneficial manner, is one method of augmenting the present supply. Existing eradication methods, post‐treatment control, and land‐use procedures need additional refinement and further development before a fully effective phreatophyte elimination program can be consum

ISSN:0002-8606    

DOI:10.1029/TR033i001p00072

年代:1952

数据来源: WILEY

摘要:

The problem of increased growths of non‐beneficial phreatophytes on operating irrigation projects in New Mexico and the relationship with the water supply available is shown to be one of increasing concern. The methods employed and the results of eradication programs are shown, indicating that additional experimentation and treatments must be performed prior to complete elimination of the phreatophytic growth

ISSN:0002-8606    

DOI:10.1029/TR033i001p00074

年代:1952

数据来源: WILEY

摘要:

As early as 1939, the Corps of Engineers provided funds to enable the U. S. Geological Survey to perform investigational work to determine the consumptive use of water by river‐bottom growth in the Gila River Valley near Safford, Arizona. Since that time, the South Pacific Division of the Corps of Engineers has taken an active part in fostering other investigational work by fact‐finding agencies on eradication and control of phreatophytes in southwestern United States. These activities culminated in the recent work of the Pacific Southwest Federal Inter‐Agency Technical Committee, which recommended that a 77‐mi flood channel, under study by the Corps of Engineers on Salt and Gila Rivers in Arizona, be used as a proving ground for self‐financed cooperative studies by all interested State and Federal

ISSN:0002-8606    

DOI:10.1029/TR033i001p00077

年代:1952

数据来源: WILEY

摘要:

An earthquake magnitude formula, giving the closest possible fit to magnitudes of Gutenberg and Richter [1949], is developed for the vertical component of surface waves with periods of about 20 sec from records at Pasadena. The magnitude is obtained as the sum of five terms. The first term takes account of the amplitude, the second accounts for the amplitude variation with epicentral distance, the third accounts for depth of earthquake focus (down to 100 km), the fourth is the regional correction, depending on the properties of the path of the surface waves, and the fifth corrects for the fact, verified here, that the ratio of vertical to horizontal amplitudes of surface waves varies with the magnitude. It is not possible to obtain the magnitude from the records at one station to a higher accuracy than ±

ISSN:0002-8606    

DOI:10.1029/TR033i001p00081

年代:1952

数据来源: WILEY

摘要:

The present report describes the activity of Parícutin Volcano during the first half of 1951, in a form similar to reports published earlier in these Transactions. Continuous observations of activity were made by the junior author and, when he was absent from the observatory station, by his assistant, Jesús Saldaña. The senior author visited the Volcano on March 10–12, May 24–28, and July 10–12 for a total of 11 days. On these visits, measurements were made of changes in position and elevation of points on Parícutin cone and the observational data of Gutierrez and Saldaña were reviewed and discussed. All this information was evaluated and synthesized for formal presentation by the senior author, who prepared also Tables 2–4 and

ISSN:0002-8606    

DOI:10.1029/TR033i001p00091

年代:1952

数据来源: WILEY

摘要:

Scintillation counters have been developed which have advantages over parallel‐plate ionization chambers for the low‐level alpha counting of rocks and minerals. The design, construction, and calibration of the counters is described. Two types of counters have been studied. In one type a lucite cone is used to gather light flashes from a much larger surface area of sample than is possible with a photomultiplier tube alone. However, the gain in count rate is overbalanced by decreased pulse height, loss of plateau, and additional correction factors. In the second type of counter no cone is used, but the sample area is essentially infinite with respect to the sensitive area of the photomultiplier tube. In this situation a count rate is obtained which is 119 pct of that of the theoretical count of a thin source. Under these conditions the background can be reduced to 0.35 counts per cm2per hour. Experiments to define the source of the background of the counters are descri

ISSN:0002-8606    

DOI:10.1029/TR033i001p00101

年代:1952

数据来源: WILEY

摘要:

A glancing examination of the National Bureau of Standards annual review of “Hydraulic Research in the United States” impresses one with the wide variety of projects which fall under the general subject of stream dynamics. Undoubtedly there are other projects in progress that are not listed in this publication. Obviously the report of this Committee should not summarize the activities in this entire field. Instead, it appears desirable to present in some detail the results of investigations that are nearing completion, have been completed, or present valuable data or experimental techniques even though work is in a continuing phase. In addition to the restriction that each investigation be more or less completed, there is the space‐ restriction necessitating the narrowing of the field even further. This report, therefore, is confined to a summary of a number of investigations on sediment transportation and related fields. Eventually the studies summarized herein perhaps will be published, at least in part. A preview, however, of this information in a single report is of int

ISSN:0002-8606    

DOI:10.1029/TR033i001p00114

年代:1952

数据来源: WILEY