基于水质目标的小清河流域邹平段污染物综合治理效果评价

    Evaluation of the comprehensive pollution control effectiveness in the Zouping section of the Xiaoqing River Basin based on water quality targets

    • 摘要: 实施综合治理措施是改善流域水环境、提升水质的有效手段之一,进行效果评估是检验治理措施成效的关键。以小清河流域邹平段为研究对象,对3种影响该流域水质的主要污染物(NH3-N、TN、TP)进行治理。根据污染物负荷的来源,从流域的点源、面源及外源提出了不同治理措施并进行5种组合。利用土壤和水评估工具(soil and water assessment tool,SWAT)模型对不同降水情况下5种情景进行模拟,分析各情景中治理措施实施后NH3-N、TN、TP浓度状况,并结合 R-R-V(reliability-resilience-vulnerability)指数法和熵值法对不同情景治理措施的治理效果进行综合评价。结果表明:不同措施组合的治理情景均能够改善水质状况,其中S5(城镇污水处理率提高到100%,农村污水处理率提高到80%,裸露地减少30 km2,上游负荷减少40%,施肥量减少40%)情景下,唐口桥断面丰水年、平水年和枯水年均达到Ⅲ类水质目标。不同降雨情况下,S5情景综合得分最高,丰水年和平水年均为0.96,枯水年为0.88,该情景的治理措施对水质改善效果最佳。因此,R-R-V 指数和熵值法相结合能对综合治理措施的效果进行评价,并为小清河流域邹平段水质管理目标的实现提供治理措施筛选的依据。

       

      Abstract: Comprehensive pollution control is one of effective means to improve water environment and water quality, and the assessment of its effects is a key to test the effectiveness of these control measures. Xiaoqing River is located in the lower reaches of the Yellow River. It is an important drainage channel of Shandong Province. The river is a source of irrigation of farmland on both sides, and is used for river transport and access to the sea. However, the Zouping section of the Xiaoqing River basin has high concentrations of NH3-N, TN, and TP, which do not meet water quality objectives. Focusing on the Zouping section of the Xiaoqing River Basin, three major pollutants affecting the water quality of the basin (NH3-N, TN, TP) were treated. According to the source of the pollutant load, comprehensive control measures combining internal and external sources are considered from the aspects of upgrading the sewage treatment plant, centralised collection and treatment of rural sewage, reduction of fertiliser application, regional afforestation and reduction of upstream incoming water load. Five combinations were created. The SWAT model was established based on the basic data of the basin and the parameter rates were determined to simulate the five treatment scenarios under different precipitation conditions, and to analyse whether the concentrations of NH3-N, TN, and TP could reach the target of Class III water quality of surface water after the implementation of the control measures. A combination of the R-R-V (Reliability-Resilience-Vulnerability)index method and the entropy method were used to assess the effectiveness of the combined measures in terms of reliability, reparability and vulnerability. On this basis the best measure were selected. The results showed that different combinations of control measures were able to improve the water environment condition. The concentrations of NH3-N, TN and TP after the five treatment scenarios were significantly lower than those before the treatment under abundant, flat and dry precipitation, and the annual average concentrations of pollutants in the control scenarios of S2, S3, S4, and S5 were able to reach the target of Class III water quality. Under S5 (the scenario including urban sewage treatment rate increased to 100%, rural sewage treatment rate increased to 80%, bare land reduced by 30 km2 , upstream load reduced by 40%, fertiliser application reduced by 40%), the monthly concentrations of pollutants in the Tangkouqiao section reached the target of Class III water quality during wet, normal, and dry years. The S5 scenario had the highest composite score under different rainfall scenarios, with 0.96 and 0.96 in the year of abundance and flat water, respectively, and 0.88 in the year of dry water, which demonstrated the best effect of treatment measures on water quality improvement. This study proves that the R-R-V index method and entropy method are good for assessing the effectiveness of combined control measures. This study also provides a way to implement water quality management targets in the Zouping section of Xiaoqing River Basin.

       

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