Strategy for cost-effective BMPs of non-point source pollution in the small agricultural watershed of Poyang Lake: A case study of the Zhuxi River.

In recent years, Poyang Lake has been affected by severe agricultural non-point source (NPS) pollution, a global water pollution problem. The most recognized and effective control measure for agricultural NPS pollution is the strategic selection and placement of best management practices (BMPs) for critical source areas (CSAs). The present study employed the Soil and Water Assessment Tool (SWAT) model to identify CSAs and evaluate the effectiveness of different BMPs in reducing agricultural NPS pollutants in the typical sub-watersheds of the Poyang Lake watershed. The model performed well and satisfactorily in simulating the streamflow and sediment yield at the outlet of the Zhuxi River watershed. The results indicated that urbanization-oriented development strategies and the Grain for Green program (returning the grain plots to forestry) had certain effects on the land-use structure. The proportion of cropland in the study area decreased from 61.45% (2010) to 7.48% (2018) in response to the Grain for Green program, which was mainly converted to forest land (58.7%) and settlements (36.8%). Land-use type changes alter the occurrence of runoff and sediment, which further affect the nitrogen (N) and phosphorus (P) loads since sediment load intensity is a key factor affecting the P load intensity. Vegetation buffer strips (VBSs) proved the most effective BMPs for NPS pollutant reduction, and the cost of 5-m VBSs proved the lowest. The effectiveness of each BMP in reducing N/P load ranked as follows: VBS > grassed river channels (GRC) > 20% fertilizer reduction (FR20) > no-tillage (NT) > 10% fertilizer reduction (FR10). All combined BMPs had higher N and P removal efficiencies than the individual measures. We recommend combining FR20 and VBS-5m or NT and VBS-5m, which could achieve nearly 60% pollutant removal. Depending on the site conditions, the choice between FR20+VBS and NT + VBS is flexible for targeted implementation. Our findings may contribute to the effective implementation of BMPs in the Poyang Lake watershed and provide theoretical support and practical guidance for agricultural authorities to perform and direct agricultural NPS pollution prevention and control.

Liu W ，Zhang L ，Wu H ，Wang Y ，Zhang Y ，Xu J ，Wei D ，Zhang R ，Yu Y ，Wu D ，Xie X ... -  《-》

Application of a multi-objective optimization method to provide least cost alternatives for NPS pollution control.

Maringanti C ，Chaubey I ，Arabi M ，Engel B ... -  《-》

Quantifying effects of conservation practices on non-point source pollution in the Miyun Reservoir Watershed, China.

Qiu J ，Shen Z ，Chen L ，Hou X ... -  《-》

Cost-effectiveness and cost-benefit analysis of BMPs in controlling agricultural nonpoint source pollution in China based on the SWAT model.

Liu R ，Zhang P ，Wang X ，Wang J ，Yu W ，Shen Z ... -  《-》

Research on optimal control of non-point source pollution: a case study from the Danjiang River basin in China.

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 (NH3-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.

Li H ，Zhou X ，Huang K ，Hao G ，Li J ... -  《-》