State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China, Xi'an University of Technology, No. 5, Jinhua South Road, Xi'an, 710048, China.
Environ Sci Pollut Res Int. 2022 Mar;29(11):15582-15602. doi: 10.1007/s11356-021-16740-y. Epub 2021 Oct 10.
The impact and optimal control of non-point source (NPS) pollution on water environment have become the hot issues of current research. This paper simulates the characteristics of NPS pollution of Danjiang River Basin in 2013, 2014, 2016, and 2018 based on SWAT (Soil and Water Assessment Tool) model. The spatial and temporal distribution is analyzed, and the critical source areas (CSA) according to the intensity of pollution loss are identified. Then, we set up nine single best management practices (BMPs) and three combined BMPs in the CSA, and the reduction effects of NPS pollution load of BMPs at the HRU scale and sub-basin scale are evaluated. The main research conclusions are as follows: (1) Based on the measured water quality and quantity data of Danfeng section from 2011 to 2019, the mean concentration method and the runoff division method are used to estimate the NPS pollution load at the Danfeng section, the NPS pollution loads of the total phosphorus (TP), ammonia nitrogen (NH-N) and COD account for a large proportion in the total loads, which are 60.95-75.91%, 39.43-56.40%, and 59.37-74.37%, respectively. (2) In terms of temporal distribution, the impact to NPS pollution load is ranked as runoff > sediment > rainfall. In terms of spatial distribution, sediment has a great impact on nitrogen and phosphorus NPS pollution load. (3) The unit area load index method and the natural crack point classification method are used to identify the CSA in the basin. The information-entropy-basedmulti-attribute decision-making method to evaluate the cost-benefit value of management measures shows that control measures preferentially use combined BMPs, and the comprehensive cost-benefit attribute value reaches above 0.8. When using a single BMP, the comprehensive attribute value of returning the grain plots to forestry is high, reaching 0.62, which is suitable for NPS pollution control in a small area; for large-scale NPS pollution control, terrace project, supplemented by residue cover and grassed waterways is the more effective way in the river basin.
非点源（NPS）污染对水环境的影响及其优化控制已成为当前研究的热点问题。本研究基于 SWAT（土壤和水评估工具）模型，模拟了丹江流域 2013 年、2014 年、2016 年和 2018 年 NPS 污染特征，分析了其时空分布特征，并根据污染损失强度识别了关键源区（CSA）。然后，在 CSA 中设置了 9 种单一最佳管理措施（BMPs）和 3 种组合 BMPs，评估了 BMPs 在 HRU 尺度和子流域尺度上对 NPS 污染负荷的削减效果。主要研究结论如下：（1）基于 2011 年至 2019 年丹凤断面的实测水质和水量数据，采用均值浓度法和径流量分割法估算丹凤断面 NPS 污染负荷，总磷（TP）、氨氮（NH-N）和 COD 的 NPS 污染负荷在总负荷中占比较大，分别为 60.95%75.91%、39.43%56.40%和 59.37%~74.37%。（2）从时间分布来看，对 NPS 污染负荷的影响程度依次为径流量＞泥沙＞降雨量；从空间分布来看，泥沙对氮磷 NPS 污染负荷影响较大。（3）采用单位面积负荷指数法和自然裂缝点分类法识别流域内 CSA，基于信息熵的多属性决策法评价管理措施的成本效益值，结果表明控制措施优先采用组合 BMPs，综合成本效益属性值大于 0.8；采用单一 BMP 时，退耕还林的综合属性值较高，达到 0.62，适用于小面积的 NPS 污染控制；对于大规模的 NPS 污染控制，梯田工程辅以秸秆覆盖和草沟是流域内更有效的方法。
