广东省典型流域突发水污染事件风险评估技术及其应用

Watershed-scale environmental risk assessment for typical accidental water pollution accidents in the east of Guangdong Province

为了探索一种适合广东省流域环境风险特征的评估技术,以解决＂多源-多受体-多影响＂大尺度评估难题,并提出有效措施防范突发水污染事件。以＂相对风险评估＂为核心,统计分析近4年广东省突发水污染历史事件,总结流域风险特征,构建评估概念模型;提出不同情境下评估单元划分方法,应用评分法和矩阵法进一步优化环境风险要素量化过程,尤其是面源;引入水质模型和Arc GIS空间分析技术,确定风险要素间的相互作用关系,提高了方法的科学性。重点以揭阳引榕干渠流域为例开展实践应用,4.5%的相对误差一定程度上验证了方法的有效性和稳定性。流域环境风险总体分布为下游最高、中游次之、上游最低,沿水流方向风险累积性和传递性明显。暴雨条件下上游高浓度来水和第一水厂取水口是风险重点管理对象,评价终点应优先关注人员安全和生态安全,风险分区防范重在减缓危害性和降低脆弱性。

The article is aimed at making an exploration of scientific and reasonable watershed environmental risk for the north-eastern part of Guangdong so as to work out the effective measures to prevent abrupt water pollution accidents（ AWPA）. What we mean the watershed-scale risk may involve multiple hazard sources,receptors and complicated interactions among all such factors. Therefore,we have managed to modify the relative risk assessment（ RRA for short） so as to make it applied more effectively to the AWPA. For this purpose,we have first of all analyzed the AWPA in recent 4 years by summarizing the risk-involving factors,the damages and management targets so as to build up a conceptual model of RRA. Furthermore, we have also brought about the division method of evaluation zone in the different scenarios,so as to optimalize the quantitative process of the environmental risk factors,especially the surface source through scoring and matrix approaches. And,finally,a water quality model and Arc GIS software have been taken to determine the exposure and effect filters to characterize and determine the comprehensive risks. And,in general,the study areas of ours can be said covering the main canal of Rong River diversion project in Jieyang City,for the river serves as the upstream of drinking water intake. The results of our on-spot investigation and observation prove that the actual risk faced by the river tends to be much greater in its middle and lower reaches,with the upper reach being less harmed. However,the upstream surface source can be most dangerous during the days of rainstorm,which is followed by S12,with the drinking water intake of the first water plant being the most vulnerable receptor. Therefore,it is necessary for the local governments to provide most serious concern for the ecological risk prevention and focus on reducing the drinking water hazards.Specifically speaking,it is of great significance to intensify the upstream pollution reduction,while the environmental risk management for the industrial enterprises in the middle areas of the river should also reinforce the control and protect the sanitary level of the drinking water with their own control and managing power. Furthermore,the pollutants diffusion process should be seriously studied and greatly restricted whereas a relative error of4. 5% partially verifies the robustness and stability of the method in our uncertainty and sensitivity analysis,which says that,in the high risk zones,effective filters are responsible for a major contribution to the overcome of uncertainty.