长三角小流域AnnAGNPS模型参数敏感性及适用性评价

【目的】研究年度农业非点源污染模型(Annualized agricultural non-point source pollutant loading model,AnnAGNPS)在沛桥河小流域的参数敏感性与适用性,为长三角地区的流域综合管理工作提供数据支撑和科学依据。【方法】以长江中下游水阳江水系沛桥河小流域为研究区,采用差分灵敏度分析(differential sensitivity analysis,DSA)方法进行参数敏感性分析,通过相关系数(R²)、效率系数(E)以及相对误差(E_R)来综合评价模型的适用性。【结果】对研究区径流、总氮与总磷输出模拟最敏感的参数是径流曲线数(CN),对泥沙输出模拟敏感性程度最高的参数是CN、土壤可蚀性因子(K)、水土保持因子(P)与作物管理因子(C),且均呈正相关影响特征。验证期(2015—2018年)汛期与非汛期径流、泥沙、总氮与总磷的相关系数(R²)、效率系数(E)均大于0.80,相对误差(E_R)的绝对值均小于12%;模型对径流与泥沙汛期的模拟精度均高于非汛期,而对总氮与总磷负荷非汛期的模拟精度略高于汛期。【结论】校准后的AnnAGNPS模型应用于沛桥河小流域的模拟效果较好,可用于辅助长三角低山丘陵区农业小流域非点源污染与水土流失管理决策。

Parameters sensitivity and applicability evaluations of AnnAGNPS model in a small watershed of the Yangtze River Delta

【Objective】 The sensitivity and applicability of the agricultural non-point source pollution model AnnAGNPS to the Peiqiao River watershed were studied to provide data supports and a scientific basis for the comprehensive watershed management in the Yangtze River Delta. 【Method】 The study area is Peiqiao River watershed of Shuiyang River system in the middle and lower reaches of the Yangtze River. A differential sensitivity analysis (DSA) method was used for a parameter sensitivity analysis, and the applicability of the model was comprehensively evaluated using correlation coefficient (R²), efficiency coefficient (E) and relative error (E_R). 【Result】 The parameter with the highest degree of output sensitivity to runoff, total nitrogen, total phosphorus and sediment in the studied area was the curve number (CN). Soil erosion factor (K), soil and water conservation factor (P), and crop management factor (C), all had positive correlations and effects. The R² and E of runoff, sediment, total nitrogen, and total phosphorus in the flood season and non-flood season from 2015 to 2018 were all greater than 0.80, and the absolute value of E_R was less than 12%. The simulation accuracy of runoff and sediment in the flood season was higher than that in the non-flood season, while the simulation accuracy of total nitrogen and total phosphorus in the non-flood season was slightly higher than that in the flood season. 【Conclusion】The calibrated AnnAGNPS model has a good simulation effect and reliable results in the Peiqiao River watershed and could be used to assist decision-makings on non-point source pollution and soil erosion management in a small agricultural watershed of the hill region of the Yangtze River Delta.