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61.
The causes of degradation of aquatic systems are often complex and stem from a variety of human influences. Comprehensive, multimetric biological indices have been developed to quantify this degradation and its effect on aquatic communities, and measure subsequent recovery from anthropogenic stressors. Traditionally, such indices have concentrated on small‐to medium‐sized streams. Recently, however, the Ohio River Fish Index (ORFIn) was created to assess biotic integrity in the Ohio River. The goal of the present project was to begin developing a companion Ohio River multimetric index using benthic macroinvertebrates. Hester–Dendy multiplate samplers were used to evaluate benthic macroinvertebrate assemblages in relation to a gradient of water quality disturbance, represented by varying distances downstream of industrial and municipal wastewater outfalls in the Ohio River. In August 1999 and 2000, samplers were set every 100 m downstream of outfalls (12 outfalls in 1999, 22 in 2000) for 300–1000 m, as well as at upstream reference sites. Candidate metrics (n = 55) were examined to determine which have potential to detect changes in water quality downstream of outfalls. These individual measures of community structure were plotted against distance downstream of each outfall to determine their response to water quality disturbance. Values at reference and outfall sites were also compared. Metrics that are ecologically relevant and showed a response to outfall disturbance were identified as potentially valuable in a multimetric index. Multiple box plots of index scores indicated greater response to outfall disturbance during periods of low‐flow, and longitudinal river‐wide trends. Evaluation of other types of anthropogenic disturbance, as well as continued analysis of the effects of chemical water quality on macroinvertebrate communities in future years will facilitate further development of a multimetric benthic macroinvertebrate index to evaluate biotic integrity in the Ohio River. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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东辽河流域地下水资源比较丰富,占该区水资源总量的72%,供水量中,地下水占37.6%,同时,该区地表水资源污染相对较重,因此,地下水的开发利用越来越受到人们的重视。本文根据东辽河流域1956-2000年共45年的地下水动态资料序列,分析得出地下水动态变化的主要影响因素为大气降水、地表水及人为因素,预测地下水动态多年变化将趋于稳定。 相似文献
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云南东川泥石流沟与非泥石流沟~(137)Cs示踪法物源研究 总被引:1,自引:0,他引:1
运用1 37Cs示踪法调查云南东川小江流域 6条泥石流沟、6条非泥石流沟和主河的泥沙来源。泥沙主要来源于冲沟侵蚀和滑坡崩塌堆积、坡耕地和草地。坡耕地和草地表层土壤1 37Cs平均含量分别为 0 9Bq m2 和1 98Bq m2 ,冲沟沟壁和滑坡崩塌堆积土体1 37Cs。作者通过 3种源地土体1 37Cs含量的比较 ,分析了细粒泥沙(<0 0 1mm)的来源。 6条泥石流沟冲沟侵蚀和重力侵蚀 (滑坡崩塌 )的相对产沙量变化于 90 2 %~ 1 0 0 % ,平均值为 95 1 % ,6条非泥石流沟的相对产沙量变化于 74 5 %~ 83 3% ,平均值为 78 9%。小江主河为 81 4 %。 相似文献
66.
Fan Jing yu Wang Dao zeng Zhong Bao chang Shanghai Institute of Applied Mathematics Mechanics Shanghai University Shanghai China 《水动力学研究与进展(B辑)》2003,15(2)
1 . INTRODUCTIONUndertheinfluenceofnaturaltides,theinterac tionsbetweenflowfeaturesandpollutantlongitudinaldiffusionintidalriversareimportantforwaterenvi ronmentrectificationinestuarineregions.Thediffu sionandtransportofpollutantinnaturalriversfallin tom… 相似文献
67.
Simulation Modeling of Runoff,Groundwater Flow and Sediment Transport into Kastoria Lake,Greece 总被引:3,自引:0,他引:3
Hrissanthou V. Mylopoulos N. Tolikas D. Mylopoulos Y. 《Water Resources Management》2003,17(3):223-242
Kastoria Lake is located in northwestern Greece. The whole basin of the lake is about 253 km2. For the computation of the surface water volume inflowing into the lake from the main streams of the sub-basins located around Kastoria Lake, a rainfall-runoff sub-model is used. A quasi-three-dimensional simulation model of the Kastoria basin aquifer is also realized, in order to estimate the groundwater contribution to the volumetric budget of the lake and the whole basin as well. For the computation of sediment load inflowing into the lake from the main streams of the sub-basins, the rainfall-runoff sub-model is combinedwith a soil erosion sub-model and a sediment transport sub-model for streams. A GIS was developed in the hydrologic basin with all data needed for parameter identification and model application. The data base was enriched by a series of on site measurements of water discharge made in all main streams for one whole hydrologic year. By means of the resulting mathematical sediment model, those sub-basins, which deliver most sediment load to the lake, are identified. On the basis of this identification, a series of control measures, for the reduction of sediment inflowing into the lake, at certain places of the above mentioned sub-basins is proposed. 相似文献
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通过模型试验 ,对位于西安市东郊因采沙使河道破坏严重的灞河河段进行了复现试验和研究 ,并以此为依据 ,通过优化比较为设计部门提供了合理的橡胶坝坝址和坝座高程。在此基础上 ,又对建坝后橡胶坝对上下游冲淤变化的影响进行了试验研究和分析 ,解决了工程设计中的一些关键技术问题 相似文献
70.
泥沙悬浮的特征长度和悬移质浓度垂线分布 总被引:2,自引:0,他引:2
通过对紊动水流中混合掺长概念的类比,本文引入了泥沙作悬浮运动的特征长度的概念并讨论了其表达式的确定方法,从而在未经引入任何流速分布公式的情况下得到了一个悬移质浓度分布的统一公式,几乎所有已有各家公式均为本公式的特例。本文所采用的方法具有许多优点,采用本文的有关结果也便于从统一的高度来分析以往类似公式之间的内在联系、各公式的合理性及局限性。 相似文献