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961.
962.
Bruce N. Wilson J. William Brown 《Journal of the American Water Resources Association》1992,28(2):397-408
ABSTRACT: A generalized unit hydrograph method is developed and evaluated for ungaged watersheds. A key component in this method is the value of a dimensionless storage coefficient. Procedures to estimate this coefficient are given using calibrated values from 142 rainfall-runoff events gaged in watershed located mainly in the Eastern US. Only limited success was obtained in predicting this storage coefficient. Thirty-seven, independent rainfall-runoff events were used to test the proposed technique. The generalized unit hydrograph predicted the observed runoff hydrographs fairly well with considerable improvement in accuracy over the SCS dimensionless unit hydrograph. Approximately one-half of test storms had percent errors in predicted peak flow rates that were less than 34 percent compared to percent error of 88 percent with the SCS method. 相似文献
963.
Reuben N. Weisz Charles L. Towle 《Journal of the American Water Resources Association》1977,13(5):1035-1046
ABSTRACT: In the past, researchers have applied a variety of analytical techniques for maximizing the present value of a stock resource - simulation, calculus of variations, stochastic dynamic programming, and optimal control theory. This paper presents a more operational approach - linear programming. A simplified, broadly drawn example from Southwest agriculture is used for demonstrating the model's structure and output. The method is based on a set of state transformation operations that prevent the additivity assumption of linear programming from being violated. 相似文献
964.
David C. Davenport Robert M. Hagan 《Journal of the American Water Resources Association》1980,16(4):717-723
ABSTRACT: This paper defines types of water losses in irrigated agriculture and outlines potentials for water conservation. Recoverable water “losses” (seepage, leakage, and spillage during storage and conveyance, and surface runoff and deep percolation during irrigation) and irrecoverable losses (evaporation from water and soil surfaces and transpiration from plants) are described and illustrated. Some conservation terms are defined, particularly the distinction between on-farm irrigation efficiency and areawide efficiency. Briefly reviewed are agricultural water conservation technologies and their applicability. The biggest untapped potential for water conservation may be a reduction in irrecoverable losses, especially evapotranspiration. The advantages and disadvantages of reducing recoverable and irrecoverable water losses are described, including possible effects on ground water, energy, salinity, crops, wildlife, and in-stream uses. Such information may be useful in several policy and management issues, e.g., ground water overdraft and possible constraints on crops and sites to be irrigated. 相似文献
965.
William E. Sharpe Victoria G. Leibfried William G. Kimmel David R. DeWalle 《Journal of the American Water Resources Association》1987,23(1):37-46
ABSTRACT: A survey of 61 headwater streams and their watersheds on Pennsylvania's Laurel Hill, an area of high hydrogen ion and sulfate deposition, was conducted in May and June 1983. Trout were absent from 12 or 20 percent of the streams. No fish were present in 10 streams. Thirty-three streams appeared to contain viable trout populations, 10 streams had other interferring cultural impacts and 6 streams had nonviable trout populations. Significant differences in water quality were noted among streams with and without fish. The streams having no fish as a group had significantly lower pH and alkalinity and higher dissolved aluminum than those with fish. Attempts were made to correlate soil type and geology with the presence or absence of trout. Watersheds with a major percentage of very stony land soil classifications always contained no trout or were culturally impacted. On the other hand, watersheds with a major percentage of Upshur (limestone derived) soils always supported trout. Watersheds with more than 30 percent Pocono Group bedrock supported trout in every case but two, while in every case but one, watersheds with more than 30 percent Pottsville Group bedrock did not support trout. Acid runoff episode data indicate severe transient acidification attributable to atmospheric deposition. It appears that a combination of very stony land, 30 percent Pottsville Group bedrock and high deposition of hydrogen ions and sulfate may result in transient acidification and absence of fish populations from headwater streams on Pennsylvania's Laurel Hill. 相似文献
966.
J. Walter Milon 《Journal of the American Water Resources Association》1987,23(3):387-396
ABSTRACT: A stochastic programming framework is developed to evaluate the economic implications of reliability criteria and multiple effluent controls on nonpoint source pollution. An integrated watershed simulation model is used to generate probability distributions for agricultural effluents in surface and ground water resulting from agricultural practices. Results from the planning model indicate that reliability and multiple effluent constraints significantly increase the cost of nonpoint controls but the effects vary by control alternative. The analysis indicates that an evaluation of multiple water quality objectives can be an important planning tool for designing nonpoint source controls for innovative programs to promote cost-effective water quality regulation. 相似文献
967.
William F. McTernan Barron L. Weand Thomas J. Grizzard 《Journal of the American Water Resources Association》1987,23(4):691-700
ABSTRACT: The objective of this study was to evaluate the effectiveness of various land-use practices upon the production of nonpoint source pollutants from small agricultural watersheds in Northern Virginia. Pollutant production at each watershed was determined by individual monitoring stations. Data analysis consisted of a determination of the site specific pollutant yield for similar watersheds subjected to differing crop management approaches. These collected data were then compared to those generated by a parametric, event model developed for this investigation. This synthetic data base was used to eliminate or reduce errors resulting from monitoring site differences and to extend the collected data for additional comparisons. 相似文献
968.
Charles R. Kratzer William Dritschilo Lee J. Hannah Marlene A. Broutman 《Journal of the American Water Resources Association》1985,21(4):565-572
ABSTRACT: An input-output model was developed to predict changes in Salton Sea salinity and water level until the year 2000 due to proposed water conservation efforts and geothermal and solar pond energy developments. The model SALINP provided good agreement with the observed salinities for 1960–80. While SALINP was not overly sensitive to one-year changes in any of the major inputs, a change in the historical means of the Imperial Valley runoff and evaporative loss inputs produced a significant effect on future predictions. The proposed water conservation measures caused the predicted Salton Sea salinity for 2000 to greatly exceed 40,000 ppm, the level at which adverse effects to wildlife are believed to occur. The possible geothermal development also produced predicted salinities considerably above 40,000 ppm. The salinity predictions for solar ponds by themselves and in conjunction with geothermal development were below 45,000 ppm for 2000. The solar pond and geothermal combination also resulted in a predicted lowering of the “natural” water level by 5 to 7 feet by 2000. 相似文献
969.
本文通过对南昌市名特优农产品资源、生产现状和市场条件的综合分析,确立了发挥地区资源优势,重点发展的名特优农产品,并进行了科学合理的规划和布局。 相似文献
970.
三峡工程库区环境地质灾害的管理系统 总被引:3,自引:0,他引:3
环境地质灾害是制约地区经济发展的重要因素,本文根据资源开发与环境地质灾害之间的相互关系,结合三峡工程库区地质灾害的特点,提出了包括监测系统、信息管理系统、决策支持系统和专家系统等环境地质灾害管理系统的设想和思路,并就该系统建立和运行过程中的有关问题进行了探讨。 相似文献