丰乐河流域磷污染输出特征及最佳管理措施

Characterization of phosphorus pollution output and best management practices in the Fengle River basin

为了更好地防控丰乐河流域的面源磷污染,通过该流域水文和水质数据对SWAT模型的径流和总磷(TP)参数进行率定与验证,模拟2011—2021年流域TP负荷时空分布特征,分析最佳管理措施(BMPs)对TP输出的削减效果。结果表明:时间分布上,流域年均TP输出量为77.58 t,2020年TP输出量最多(141.65 t),是2019年的4.3倍;TP输出主要集中在汛期(5—10月),占全年输出量的70.1%。空间分布上,耕地占比较高的子流域TP负荷强度高,其空间差异性与土地利用密切相关;耕地与林地在汛期、非汛期月TP负荷相关系数分别为0.9247、0.4193。减量化施肥、植被缓冲带和植草河道能有效削减TP输出,单个BMPs中植被缓冲带对TP削减效果最好,实施综合管理措施对流域TP削减效果最佳,年削减率达43.41%~61.23%。丰乐河流域磷污染输出受降水特性和土地利用共同影响,通过减量化施肥、设置植被缓冲带或植草河道能够有效减少TP输出。研究成果可为相关区域控源减排提供理论依据和方法借鉴。

This study used water quantity and water quality data to calibrate and verify the runoff and total phosphorus(TP)parameters of the SWAT model to better control non-point source phosphorus pollution in the Fengle River basin.It modeled the spatiotemporal distribution characteristics of TP loads in the basin from 2011 to 2021 and analyzed the reduction effects of best management practices(BMPs)on TP output.The results showed that temporally,the basin′s annual average TP output was 77.58 tons,with the highest TP output(141.65 tons)in 2020,which was 4.3 times that of 2019.TP output was concentrated primarily during the flood season from May to October,accounting for 70.1%of the annual output.Sub-basins with a high proportion of farmland had high TP load intensities,with spatial variations closely related to land use.The correlation coefficients for TP load between farmland and forest land during the flood season and non-flood season are 0.9247 and 0.4193,respectively.Reduced fertilization,filter strips,and grassed waterways were effective in reducing TP output.The filter strip had the greatest TP reduction effect among individual BMPs.Comprehensive management practices had the greatest TP reduction in the basin,with annual reduction rates ranging from 43.41%to 61.23%.The output of phosphorus pollution in Fengle River basin is jointly affected by precipitation characteristics and land use,and the output of phosphorus can be effectively reduced by reducing fertilization,establishing vegetation filter strips or grassed waterways,and the results provide a theoretical basis and methodology for the relevant regions to control the source of emission reduction.