基于输出系数模型的呼兰河流域非点源污染输出风险分析

Risk Assessment of Non-point Source Pollution in Hulan River Basin Using an Output Coefficient Model

非点源污染控制是实现流域水质改善的重要途径,通过风险评估识别重点污染区域并进行分区管理是流域非点源污染治理的最有效手段。以呼兰河流域为研究对象,收集国内外文献输出系数,利用随机模拟的方法,结合GIS技术估算了流域非点源污染输出风险。结果表明,呼兰河流域非点源污染发生率较高,氮平均输出风险达到40.48%,磷平均输出风险达到17.11%,氮为流域内主要非点源污染物质。流域的非点源污染呈现支流重于干流的现状。结合县级行政区划对估算结果进行分析发现,望奎县污染最为严重,绥化市和海伦市次之,庆安县与绥棱县相对风险较小。根据输出风险估算结果,对呼兰河流域进行管理分区,解析得到30.27%的区域属于高风险区,7.27%的区域属于极高风险区,非点源污染对流域的潜在威胁较大,有必要对高风险区域进行优先控制,并对不同等级的风险区制定相应管理措施,为流域非点源控制以及水质改善提供理论支持。

Reducing non-point source pollution is an important way to improve water quality of a river basin. Identifying priority areas through risk assessment and implementing partitioned managements would effectively control non-point source pollution. In this paper, the risk of nitrogen and phosphorus to Hulan River Basin was estimated using the random simulation method and GIS technology based on their output coefficients collected from the literatures. In the Hulan River Basin, N was the major pollutant, the incidence for N and P risks was 40.48% and 17.11%, respectively. Wangkui county had the most serious pollution, followed by Suihua and Hailun, and the least risk in Qing′an and Suiling. Non-point pollution was more serious in the tributaries than the mainstream. Based on the risk assessments, Hulan River Basin was divided into five management regions. The high-risk region accounted for 38.54% of the total watershed area, indicating high risk of non-point source pollution in the Hulan River Basin. These results would provide useful information for controlling non-point pollution and improving water quality in the Hulan River Basin.