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991.
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
992.
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
993.
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
994.
995.
996.
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
997.
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
998.
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
999.
Duane C. Wollmuth John H. Schomaker Lawrence C. Merriam 《Journal of the American Water Resources Association》1985,21(5):851-857
The Recreation Opportunity Spectrum (ROS) system is used by the USDA Forest Service and USDI Bureau of Land Management for inventorying, classifying, and managing wildlands for recreation. Different ROS classes from the Colorado and Arkansas Rivers in Colorado were compared, using visitor survey data collected in 1979 and 1981, to see if the different classes offered different recreational experience opportunities. No difference between classes was found. Six possible reasons for not finding a difference are discussed. The usefulness of ROS at the broader levels of planning and the needs at more detailed levels of planning are noted. 相似文献
1000.
沿海油田污染物入海通量及优化管理 总被引:3,自引:0,他引:3
胜利油田所在的黄河三角洲诸条河流按入海类型分为三种形式:设有防潮闸的感潮河;设有排涝站的入海河;直流入海的感潮河。按照各河流入海段面、流速、流量和水体污染物浓度,建立起各种感潮河污染物入海通量模式,计算结果说明沿海油田排放的石油类污染物入海通量为1456t/a,COD入海量为5720t/a。根据各条入海河流不同功能和污染物入海量,按照国家地表水质标准,制定出入海河流环境组合目标,用总量控制方法提出污染源削减要求,以保证黄河三角洲沿海滩涂环境质量。并以污染物入海通量、河流径流量、污染物自净系数和污染物削减量等因子建立各条河流优化管理模型,为保护环境提供对策。 相似文献