水资源短缺是全球性关注的问题,水质恶化更加剧了这一问题的严重性,定量研究水质变化及其影响因素可为治理水环境提供基础依据. 与实测数据及综合污染指数的对比表明,水质指数能够合理反映水质的变化程度和时空变化趋势. 利用西苕溪流域1996-2000年水质监测数据的研究结果如下:西苕溪流域水质的空间变化趋势是自上游至下游逐渐恶化,时间变化的总体趋势是逐年转好;点污染源得到有效控制年份(1999年)的水质指数比以前年份(1996-1998年)有所提高但幅度不大,说明非点源污染是影响西苕溪流域水质的重要因素;流域水污染的主要形式是氮、磷污染,其主要非点源是农田、经济竹林和城镇径流及居民生活污水等.
The scare of fresh water has been becoming a focus issue in the world, while water quality deterioration enhances the seriousness of the problem. To assess the water quality and its impact factors can provide basic information for water resource management. This paper verified the usefulness of water quality indices (WQI) to assess the water quality from multiple measured parameters, and to evaluate the spatial and temporal change. The WQI which takes into consideration all the measured parameters not only shows a similar trend to the results of analyzing separate parameters and the index of compositive pollution, but also display the overall water quality and can predict precisely the change trend of water quality. As a case study, we use the WQI to evaluate spatial and temporal changes in the water quality from Xitiaoxi Catchment, upper reaches of Taihu Basin, and assess the degree of factors influencing water quality. The nonpoint source pollution caused by land use produces a serious and negative effect on the water quality because only controlling and management point sources only increase 6.5% of water quality. The water quality gradually deteriorated along the river from upper reaches to lower reaches mainly due to the land use change. So, in the future, the highest priority measure to improve water quality of Xitiaoxi Catchment should be controlling non-point pollution resources.
Journal of Lake Science