摘要:

ABSTRACT:Flood frequency analyses are frequently being made using widely available computer programs. Serious errors can result from blind acceptance of such results. Visual interpretation of observed flood series can be used for evaluation on frequency paper with compatible scales. Such frequency papers are presented in the paper. In ephemeral streams, more infrequent floods may constitute a separate set from the more frequent floods because (a) runoff producing storms cover only a portion of the contributing area, (b) transmission losses in the normally dry streambed may reduce the peak flow, and (c) some runoff may be stored in stock water ponds which therefore leads to partial area runoff. The Cunnane plotting position used in this paper is superior to the more widely used Weibull equation, having a mathematically sound basis for locating observed floods on an assumed probability.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1981.tb02591.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACT:Longitudinal succession indicates that diversity and species richiess of fish communities increases with increasing river size (increasing habitat complexity and environmental stability). Cultural impacts tend to decrease diversity, species richness, and evenness. To assess the impacts of cultural events on the fish community of a river system, the bias caused by longitudinal succession was removed by normalizing diversity indices and species richness values for river size. The relationships between an impact index and the community parameters of evenness, normalized diversity, and normalized species richness were determined by regression analysis. Similar relationships were determined using nonnormalized data, and the results compared. The two sets of regressions were similar in terms of variance explained. Evenness, which is unaffected by longitudinal sucession, appears to be the most impact sensitive parameter. A major source of error and confusion rsults from introduced species which are simultaneously sources of biological impact and a component of the community. Numbers of introduced species tend to increase with both impact and river size.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1981.tb02592.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACT:Evaluation of hydrologic methodology used in a number of water balance studies of lakes in the United States shows that most of these studies calculate one or more terms of the budget as the residual. A literature review was made of studies in which the primary purpose was error analysis of hydrologic measurement and interpretation. Estimates of precipitation can have a wide range of error, depending on the gage placement, gage spacing, and areal averaging technique. Errors in measurement of individual storms can be as high as 75 percent. Errors in short term averages are commonly in the 15‐30 percent range, but decrease to about 5 percent or less for annual estimates. Errors in estimates of evaporation can also vary widely depending on instrumentation and methodology. The energy budget is the most accurate method of calculating evaporation; errors are in the 10–15 percent range. If pans are used that are located a distance from the lake of interest, errors can be considerable. Annual pan‐to‐lake coefficients should not be used for monthly estimates of evaporation because they differ from the commonly used coefficient of 0.7 by more than 100 percent. Errors in estimates of stream discharge are often considered to be within 5 percent. If the measuring section, type of flow profile, and other considerations, such as stage discharge relationship, are less than ideal errors in estimates of stream discharge can be considerably greater than 5 percent. Errors in estimating overland (nonchannelized) flow have not been evaluated, and in most lake studies this component is not mentioned. Comparison of several lake water balances in which the risdual consists solely of errors in measurement, shows that such a residual, if interpreted as ground water, can differ from an independent estimate of ground water by more than 100

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1981.tb02593.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACT:A Visual Perception Test, consisting of photographic slides of water sites, was designed to examine laymen's water quality perceptions. The slides were taken at five water sites where the level of visual pollution was artifically altered by the investigator. Analysis of variance indicated that the water sites were evaluated differently for each of five pollution levels. Increases in water discoloration and the quality of litter were viewed as increases in level of pollution. Laymen not only evaluated visually polluted sites lower for uses such as picnicking, but they also evaluated the quality of the actual water lower. Stepwise multiple regression indicated that a combination of water color, scenic beauty appreciation, quality of the surrounding environment and industry as a pollution source explained 73 percent of the variance in predicting Overall Pollution. Application of factor analysis simplified the variables to an Overall Pollution Factor and a Boating Use Factor.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1981.tb02594.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACT:On June 15, 1977, an unusual brightness anomaly was detected in the north arm of Great Salt Lake, Utah, on NOAA‐5 Very High Resolution Radiometer (VHRR) visible band imagery and on Landsat‐2 multispectral visual band imagery. Retrospective inspection of NOAA‐3, 4, and 5 satellite imagery from 1974–77 revealed 12 previous cases of the anomaly, whereas post monitoring documented nine other cases through May 1978. Comparison of lake levels in the north arm with meteorological parameters leads to the conclusion that the anomalous brightness is associated with wind induced seiches in the north arm. Apparently the wind induces a lower water depth, turbulence, and mixing throughout the water column in the western third of the north arm, thus increasing the brightness of the surface waters chiefly from sediment resus

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1981.tb02595.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACT:The accounting and repayment practices employed by the Water and Power Resources Service (WPRS) greatly distort the actual resource allocation process and the ultimate repayment to the Federal Treasury. Through a series of transfers of capital repayment obligations to future development with modest or no interest charges, the repayment is reduced to only a fraction of the amount implied. In the case of the Pick‐Sloan Missouri Basin Program, the public subsidy of hydroelectric power is estimated to be $2 for every $1 of repayment. For irrigation investment, the direct repayment to the Federal Treasury is less than 10 percent of the annualized cost of the public investment, with irrigators repaying at a rate of less than $0.03 for every dollar of public expenditur

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1981.tb02596.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACT:Nebraska statutes give first preference for use of ground water to domestic purposes, second to agriculture, and third to manufacturing or industrial purposes.Rapid growth in the number of irrigation wells has caused an increasing number of water use conflicts. One such conflict arose from the installation and use of an irrigation well near Madison in Madison County, Nebraska. Pumping from the irrigation well coincided with head declines in nearby domestic wells screened in the same sand and gravel, but appeared unrelated to water level changes in wells screened in a higher saturated sand.A drawdown‐recovery test was performed to determine the degree of hydraulic connection between the wells involved. Operation of the irrigation well was determined to be the cause of the head decline in nearby domestic wells screened in the same sand and gravel.Partly as a result of this conflict, legislation recently introduced into the state legislature would require that wells of higher preference be “reasonably” constructed if wells of lower preference are to be held liable for head

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1981.tb02597.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACT:Older inland lake communities in Wisconsin are more likely than many areas to have degraded water supplies. Many home sites are on sandy soils with high water tables and have shallow wells close to their own or a neighbor's septic system. Yet unless major rehabilitation is undertaken, these homes are relatively exempt from local codes and regulations. They also are beyond the application of the federal Clean Drinking Water Act. An Extension education program was created in response to the problem. At a community's request, home drinking water “screening tests” are conducted for at least coliform bacteria, chlorides, and nitrate/nitrite‐N. Test results, together with explanations and recommendations are reported at a local meeting. Public response has been positive, and a surprising number of wells appear to be contaminated to some d

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1981.tb02598.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1981.tb02599.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1981.tb02600.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY