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991.
Philip B. Bedient Wayne C. Huber James P. Heaney 《Journal of the American Water Resources Association》1975,11(3):469-482
ABSTRACT: An environmental simulation model of the Upper St. Johns River Basin, Florida, has been developed in order to predict hydrologic responses under proposed management plans. Land use projections for each of 19 hydrologic planning units are provided by a linear programming analysis of agricultural activities. Inputs to the model include rainfall, runoff, evapotranspiration (ET), aquifer properties, topography, soil types, and vegetative patterns. A water balance is developed in the uplands based on infiltration, ET, surface runoff, and groundwater flow. Valley continuity is based on stage-volume relationship for inflows and outflows and a variable roughness coefficient dependent on vegetative patterns. Land use changes form the basis for predicting hydroperiod variation under alternative management schemes. Plans are ranked according to two criteria, deviation from a natural hydroperiod and flood or drought control provided. Results indicate that (1) a single reservoir without irrigation and (2) floodplain preservation plans are superior to (3) multiple reservoir with irrigation and (4) uncontrolled floodplain plans with regard to both criteria. 相似文献
992.
Laboratory observations were made on the stability of cubical blocks subjected to plunging water jets. The blocks were placed in a plunge basin at the base of a flip bucket. A dimensionless equation was derived and a nomogram was drawn to facilitate its solution. The results can be applied to determine the size of stones required to armor a plunge basin or scour hole. 相似文献
993.
Scott B. Franklin Thad Wasklewicz Jack W. Grubaugh Sabine Greulich 《Journal of the American Water Resources Association》2003,39(3):637-648
ABSTRACT: Periodic flood disturbance is a well known controlling factor of in channel and floodplain ecosystem function. However, channel manipulations during the last century have potentially altered hydrologic fluctuations, and thus ecosystem function. We examined temporal river stage hydrology, through autocorrelation analysis, at seven gauges along the Mississippi River to quantify flow periodicity and effects of systematic channel modifications on flow periodicity. Intraannual variation follows a strong one‐year cycle of six months higher flow and six months lower flow for the entire Mississippi River drainage, with precipitation as a driving force. Interannual hydrologic variation differs between the upper and lower river segments. A clear quasi‐biennial oscillation pattern was evident throughout the lower river section. The effect of channel alterations was a decreased magnitude of differences between lower and higher flows. The upper section, however, suggests a 12‐to 14‐year periodicity prior to alterations and a decreased duration of lower flow years following systematic modifications. Interannual variograms clearly depict very different temporal hydrology between the upper Mississippi River and the lower Mississippi River, suggesting the simple transfer of knowledge from one segment to the other oversimplifies the complexity of a large river system. 相似文献
994.
贾生元 《中国环境管理干部学院学报》2002,12(2):31-35
国际性河流由于其地缘关系而与国家间的的政治、经济、外交等密切联系,并引起多起国际水事争端。本文以中俄界河——黑龙江为例,从水资源开发利用、水环境现状及两国经济发展的实际出发,探讨了黑龙江流域的生态环境保护与可持续开发利用问题。 相似文献
995.
塔里木河上游及源流区草原荒漠化及其防治研究 总被引:3,自引:0,他引:3
加强生态环境保护和建设是西部大开发的战略重点。针对塔里木河流域环境恶化、草地开发利用失衡、草原荒漠化日趋严重的问题,提出具体规划和综合治理方案。 相似文献
996.
997.
998.
ABSTRACT: The longitudinal dispersion of tracer material in rivers is simulated by a dead-zone model that involves two coupled differential equations. For an instantaneous injection of tracer material, the problem is solved by the Laplace. Transform and numerical inversion to obtain the time-concentration curve at any sampling station. The optimal values of the model parameters are estimated from field measurements. Applications of the model to three different rivers generally show that the model reproduces the longitudinal dispersion characteristics in natural streams with sufficient accuracy. 相似文献
999.
Richard A. Cole Frank A. Ward Timothy J. Ward Robert M. Wilson 《Journal of the American Water Resources Association》1990,26(4):597-609
ABSTRACT: This paper describes the development of an interdisciplinary model that analyzes the effects of resource management decisions on New Mexico fishery production, yield, sportfishing effort, and economic benefit to anglers. The model recreates river flows and materials transported through reservoirs and their tailwaters from 1974 through 1987. Solar radiation, water temperature, phosphorus, nitrogen, suspended solids, and water exchange rates determine primary production. Organic loads from watershed sources, added to primary production, form a trophic base for sportfish forage. Fish production is partitioned into biomass and growth of each age class in sportfish and forage fish groups by differential responses to food type, light, water-level fluctuation and predation. Fish biomass, with angler population distribution and site condition, contributes to determining angler effort and economic benefits. Model users can vary and analyze water level and quality, stocking, fishing regulations, site access, site facilities, and site entry fees. The model (on floppy disks with a user manual) is available for operation on MS DOS compatible computers with a hard disk. Contact R. M. Wilson, NMGF, State Capitol, Santa Fe, New Mexico, 87503. 相似文献
1000.
本文阐述了黄泛平原土壤侵蚀的特点,对侵蚀的形式、程度及严重危害,作了比较详细的分析,并从宏观上提出了一些防治对策。 相似文献