基于关键源区识别的饮用水水源保护区划研究

Drinking Water Source Divisions Based on Identification of Critical Source Areas

准确划定饮用水水源保护区是实现饮用水安全精细化管理的重要前提.基于源头削减和全过程协同管理的思路,将GIS平台、Arc SWAT模型、成本-效益分析技术相结合,以贵州省红枫湖饮用水水源保护区为例,通过对近5年(2010—2014年)水污染负荷特征进行模拟,识别影响水环境污染控制的关键源区,在此基础上划定水源保护区.结果表明:(1)研究区总氮、总磷污染负荷主要来源为农业面源,其中农业种植和畜禽养殖的负荷贡献分别达到89.7%和91.8%,总氮和总磷负荷高风险区主要集中在流域西北部地势较高且农业耕作活动频繁区域;(2)污染控制措施的成本效益分析表明,测土配方施肥、1°~15°坡耕地等高植物篱、保护性耕作、植被缓冲带的成本-效益比较高,在该区域水环境污染控制中具有较高的推广应用价值;(3)基于水污染关键源区识别结果,划定饮用水源四级风险区,其中一级、二级风险区总面积为97.6 km^2,仅占原饮用水水源一、二级保护区面积的41.4%,可削减总氮、总磷负荷的60%~70%,所需的搬迁成本仅为原划定方案的35%.研究结果可为我国中西部人口密度大且逐水而居的地区饮用水水源保护区及管控政策的制订提供理论基础和技术参考.

With safe drinking water essential for human well-being,a holistic and adaptive framework is necessary to protect drinking water sources and consumer supply infrastructure. In this paper,GIS technology,the Soil and Water Assessment Tool（SWAT） nonpoint source model,and remedial cost-effectiveness analysis were used to assess strategies for rezoning drinking water source areas in the upper watershed of the Hongfenghu Reservoir. This reservoir is the major drinking water source for Guiyang City. The results show that：（1）Agricultural non-point sources were the major cause of water pollution; Total nitrogen（TN） and phosphorus（TP） load from tillage and livestock sources accounted for 89. 7% and 91. 8%,respectively; TN and TP loads were primarily from the towns of Liuguang,Huangla,Jiuzhou and Baiyun,which were identified as the critical towns for water pollution control.（2） Soil testing and fertilizer recommendations,contour hedgerow strips,conservation tillage,and buffer strips were the most cost-effective control practices in the reservoir watershed;（3）Four grade zones for drinking water source protection in the reservoir watershed were divided into divisional zones. The area of first and second grade zones was 97. 6 km^2 and accounted for 41. 4% of the original drinking water protection zones,where a 60%-70% reduction in pollutant load could be achieved through implementation of best management practices（BMPs） in the identified critical source areas. In the first grade zones,district policy to protect the Hongfenghu Reservoir should be implemented,including enforcement of immigrant relocation and reduction of livestock numbers,and returning land tilled for grain forestry. In the second grade zones,a series of less restrictive policies including optional partial migration（this policy can save 35% of the total cost for migration） and elimination of livestock should be implemented. In the third and fourth grade zones,a number of comprehensive policies should be implemented to achieve the most cost-beneficial actions balancing drinking water protection and local economic development. These include construction of manure storage facilities,soil testing to determineappropriate fertilizer applications,and an improvement of sewage treatment facilities of rural communities. This research can provide a theoretical and technical basis for drinking water source area protection in similar regions of the country,where water quality is impaired and protection is required.