太湖流域地表水资源分质评价及水质型缺水形势分析

太湖流域水资源供需矛盾主要体现为"水质型缺水"问题,如何对"水质型缺水"进行定量描述,在太湖流域是一个难题.本文提出了"分质水资源量"的概念,以流域水资源四级分区为单元,以分区水质监测资料结合水资源量进行分析,分别统计分区分质水资源量.分析表明:太湖流域142×10⁸ m³的地表水资源量中,Ⅲ类以上的适合于饮用水源和一般工业用水的优质水为35.8×10⁸ m³,占25.2%;适合于电力冷却用水、农业灌溉的Ⅳ-Ⅴ类水为46.4×10⁸ m³,占32.6%;不可利用的劣Ⅴ类水有59.9×10⁸ m³,占42.2%.流域内优于Ⅴ类(含Ⅴ类)的地表水资源量为82.2×10⁸ m³,占地表水总资源量的57.8%.而浅层地下水己基本被污染.需要指出,Ⅰ-Ⅲ类优质水虽仍有35.8×10⁸ m³,但目前流域内对Ⅰ-Ⅲ类水的需求量己达60.6×10⁸ m³,如将此两数对比,则优质水缺额为24.8×10⁸ m³,但实际上,优质水的需求主要集中在流域中下游,而可供优质水水源则主要集中在流域上游地区山区水库和中游太湖湖心区、东部湖区和太浦河,供需两者的空间分布有较大出入,因此优质水资源缺额将更大,由此可见太湖流域水质型缺水形势十分严峻.

Water Quality Assessment and Shortage Analysis Caused by Pollution in the Taihu Basin

The Taihu Basin is located in the southern part of the Delta of the Yangtze River in China. The most part of the basin belongs to a plain area with a dense river network. Nowadays, the water shortage caused by pollution has become a big problem for the sustainable water utilization in Taihu Basin. In this research, a daily precipitation and runoff model was firstly introduced to analyze the daily runoff process in the typical years and evaluate the availability of water resources in the basin. Secondly, a catchment water balance with water quality issue was made between the water demand and supply. The key point of the catchment water balance lied in comparison of the monitored water quality in the water intakes with the required water quality by the different water users. This comparison reveals that the water quantity is not the major problem in the basin, because the Taihu basin can divert abundant water from the Yangtze River and the reuse rate of water resources in the basin is rather high. However, if the water quality issue is considered, there surely exists a severe water shortage caused by water pollution in the basin. Over the past 20 years, with the rapid development of agriculture and industry and the growing urbanization rate in the lake basin, the water quality of the Taihu Lake has been severely polluted and adversely influenced beneficial uses such as water supply, fisheries, recreation and amenity etc. According to the estimation, the total runoff in Taihu basin is amounted to 14.2 billions m³, of which 42% has been severely polluted (worsen than class V). The demand of water resources with a good quality has been rising since 1980s. There is a shortage of 2.48 billions m³ water with good quality nowadays. The water shortage caused by pollution will strongly affect the sustainable social and economic development in the Taihu Basin in the 21st century.