太湖流域典型区污染控制单元划分及其水环境载荷评估

污染控制单元是流域水质目标管理实施的基本单元。为实现流域水生态健康，针对太湖流域特征和太湖湖泊保护的要求，提出以流域水生态功能区为基础、水系完整性原则、管理可行性和可操作性原则、囊括影响受损水体的主要污染源原则、充分考虑现有控制断面原则等5项原则为太湖流域污染控制单元划分的基本原则，综合考虑汇水区、水生态功能区边界、水系分布及其流向、污染源、控制断面、县级与乡镇级行政边界等多个指标，在GIS空间分析的支持下进行太湖流域污染控制单元划分的总体技术思路；在划分技术体系的指导下，以兼具丘陵山区和平原地貌的湖州市及其上游的安徽省部分地区为案例研究区，在相关基础数据和空间方法的支持下，将其划分为12个污染控制单元，经过专家咨询、地方验证等多轮咨询反馈和实地察看以及管理试运行，表明污染控制单元划分结果具有较好的科学性和可操作性；进而评估了各污染控制单元COD、NH4 N、TN和TP污染物的水环境载荷特征，结果表明各单元污染超载严重

DELINEATION OF POLLUTION CONTROL UNITS IN TYPICAL CASE AREA IN THE TAIHU LAKE BASIN AND ITS OVERLOADING RATE OF WATER ENVIRONMENT

The pollution control units are the base of the water quality targets management in basin scale.According to the protection requirements for the Taihu Lake and the Taihu Lake basin characteristics,the pollution control unit delineation system in the Taihu Lake basin was discussed.The pollution control unit delineation principles mainly include the principle of aquatic ecoregion being the basis,principle of river integrity,principle of management and operational feasibility,principle of including the most point and nonpoint sources of pollution,principle of trying to include the existing water quality monitoring section,etc.The main indicators of the pollution control unit delineation mainly include the subwatershed,level III aquatic ecoregion,distribution pattern and flow direction of river system,pollution source,water quality monitoring section,county and township level administrative boundaries.And the control unit delineation method is mainly the GIS spatial analysis.In this paper,Huzhou City and some places in Anhui Province,which are the upper reaches of Taihu Lake basin and are characterized by the hills and mountains and plains landscape,were selected as the case study area.In support of the various data,and with the help of techniques of spatial analysis and expert judgment,the study area was divided into twelve pollution control units.After several rounds of consultation and feedback,including experts’ advices,government officials’ comments and the local validation of field visits as well as the application in the test of water quality target management,the results showed that the pollution control units have good scientific value and operational use.Moreover,the overloading rates of water environment in water pollution control units were calculated,and the result showed that the COD,NH4-N,TN and TP pollution load overloaded the capacity of water environment in various control units.