摘要:

ABSTRACT:The probability distributions of annual peak flows used in flood risk analysis quantify the risk that a design flood will be exceeded. But the parameters of these distributions are themselves to a degree uncertain and this uncertainty increases the risk that the flood protection provided will in fact prove to be inadequate. The increase in flood risk due to parameter uncertainty is small when a fairly long record of data is available and the annual flood peaks are serially independent, which is the standard assumption in flood frequency analysis. But standard tests for serial independence are insensitive to the type of grouping of high and low values in a time series, which is measured by the Hurst coefficient. This grouping increases the parameter uncertainty considerably. A study of 49 annual peak flow series for Canadian rivers shows that many have a high Hurst coefficient. The corresponding increase in flood risk due to parameter uncertainty is shown to be substantial even for rivers with a long record, and therefore should not be neglected. The paper presents a method of rationally combining parameter uncertainty due to serial correlation, and the stochastic variability of peak flows in a single risk assessment. In addition, a relatively simple time series model that is capable of reproducing the observed serial correlation of flood peaks is presented.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1989.tb05407.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT:Irrigation has expanded in parts of the eastern United States. In some areas, the adjoining surface (riparian) water is the most economical source of irrigation water. Expanded demand for riparian water may lead to conflict among irrigators and other streamflow users. Accurate information on the potential for and impacts of riparian irrigation expansion is needed to decide if control of such expansion is necessary. In this study, a stochastic economic model to evaluate the impacts of potential irrigation expansion is presented. The model considers the soil, location, and land use characteristics of individual sites, as well as weather and streamflow patterns. The application of the model to an eastern Virginia watershed indicates that, with maximum potential expansion, water availability becomes limited and yields will be reduced in some years. As a result, the expected net returns from irrigation and the probability of breaking even on the investment are reduced substantially. The results suggest the need to consider regulation of surface water allocation for irrigation development in riparian watersheds.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1989.tb05408.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT:A procedure is presented for estimating flooding probabilities resulting from either open water or ice condition events. The methodology involves individually fitting a distribution function to water stages from open water and ice events and determining the composite probability of exceedence of any stage value. The parameters of the two distribution functions are estimated using censored maximum likelihood. The approach is evaluated with a Monte Carlo sampling program and is applied to estimate flooding probabilities on the Yukon River.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1989.tb05409.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT:Regression and time‐series techniques have been used to synthesize and predict the stream flow at the Foresta Bridge gage from information at the upstream Pohono Bridge gage on the Merced River near Yosemite National Park. Using the available data from two time periods (calendar year 1979 and water year 1986), we evaluated the two techniques in their ability to model the variation in the observed flows and in their ability to predict stream flow at the Foresta Bridge gage for the 1979 time period with data from the 1986 time period. Both techniques produced reasonably good estimates and forecasts of the flow at the downstream gage. However, the regression model was found to have a significant amount of autocorrelation in the residuals, which the time‐series model was able to eliminate. The time‐series technique presented can be of great assistance in arriving at reasonable estimates of flow in data sets that have large missing portions of

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1989.tb05410.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT:An analysis of four streamflow generation schemes for the use in the estimation of the required conservation storage for a single reservoir is presented. The comparison of the generating schemes should aid in the selection of an appropriate model type for the reservoir sizing problem. The streamflow generation models are compared using two criteria. The first comparison is between the statistics of the generated streamflow sequences and the corresponding statistics from the historical record. The second evaluation compares the median reservoir size determined by each model with the required storage based on the historical flow sequence. The results of a comparative analysis for monthly streamflow data for the Rzav River in Yugoslavia are presented and discussed. The results indicate that both evaluation criteria are required to discriminate between the various options.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1989.tb05411.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT:Providing adequate wastewater treatment facilities for the citizens in small rural communities in the United States can cost millions of dollars. An educational program has been developed and conducted in Ohio to teach local officials about wastewater treatment alternatives. The five‐session workshop covers wastewater treatment principles, needs assessment, system management, and resource gathering. The knowledge and skills gained by the 96 community leaders who participated in six workshops were measured using a pretest/pest test and surveys conducted during the workshops. From 25 percent to 100 percent of the participants increased their knowledge of treatment systems, alternatives, and relative costs. From 23 percent to 84 percent applied new skills, such as conducting a sanitary survey or examining treatment systems. The pretest also revealed previous knowledge of the participants in the areas of system maintenance and consultant qualification

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1989.tb05412.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT:Measured stream discharge plus calculated ground water discharge (total measured runoff) were compared with runoff calculated by the unit‐runoff method for the two largest watersheds of Mirror Lake for 1981–1983. Runoff calculated by the unit‐runoff method, using Hubbard Brook watershed 3 as the index watershed, was greater than the total measured runoff into Mirror Lake during periods of high flow and slightly less than the total measured runoff into Mirror Lake during periods of low flow. Annual calculated unit runoff was 17 to 37 percent greater than total measured runoff. Differences in monthly runoff are far greater, ranging from 0 to greater than 100 percent. For high flows the calculated unit runoff is about 2 times greater than total measured runoff. For low flows the northwest basin of Mirror Lake has the greatest ground water contribution compared to the other two basins. In contrast, Hubbard Brook watershed 3 has the least ground water contrib

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1989.tb05413.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT:Several crop water stress indices were examined to determine their potential for use from a space‐based system. These indices were compared using data collected over a wheat crop grown under arid environmental conditions. Indices that required concurrent ground‐based measurements were less adaptable than the simple difference between canopy temperatures of a field with unknown stress conditions and a similar crop known to be unstressed. The results indicate that it would be feasible to develop space‐based crop water stress techniques that would be useful for scheduling irriga

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1989.tb05414.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT:Contamination of supplies by a wide variety of pollutants has long presented water managers with difficult problems. In the last fifteen years the issue of groundwater contamination has received a great deal of attention. Most work has focused on the source side of the problem. Questions have included: where do pollutants come from, how widespread is the problem, and what are the effects of the contaminants on human health and the environment? Very little work, however, has yet been done on the response side of this issue. Are water managers aware of water pollution problems (actual or potential) and their magnitude, and how well prepared are they to deal with contamination situations if they should develop? This paper reports results from a study of such questions for the southern New Jersey area. The study was intended to assess both the methodological and substantive issues involved in an empirical investigation of response capability. In addition to reporting methodological findings, the paper concludes that, while problem awareness is relatively high, actual preparedness and response capabilities are strikingly low.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1989.tb05415.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT:Soil water was monitored by neutron scattering in six soils, three each within two drainage catenas in east‐central Illinois, over a 15‐month time span. The prairie soils have formed in: (1) 76–152 cm of silt loam, eolian sediments (bess) over glacial till (Catlin‐Flanagan‐Drummer catena), and (2) bess greater than 152 cm in thickness (Tama‐Ipava‐Sable catena). We characterized the water content of these soils over the total time span and for wet and dry climatic subsets, as an aid to potential irrigation decisions. Soils of the thin bess, C‐F‐D catena dried out to lower water contents and had greater soil water variability than did the thick bess soils. Under wet conditions, soil water contents in the two catenas were quite similar. Alleviation of surface and subsurface drying via irrigation would thus be more advantageous to yields on the C‐F‐D soils th

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1989.tb05416.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY