基于SWAT模型的磷负荷削减最佳管理措施(BMPs)评估研究

基于高空间分辨（0.07 m）土地利用数据和详细的农业管理信息，利用SWAT（Soil and Water Assessment Tool）模型对关帝河子流域的农业耕作进行精细化模拟，评估了4种农业最佳管理措施（BMPs）对非点源磷负荷的削减效果.结果表明：3个水文站径流的率定结果均达到R²>0.5、NSE>0.4、PBIAS<±35%，其中，2个站点的R²>0.6、NSE>0.5、PBIAS<±5%；总磷率定的R²>0.9、NSE>0.9、PBIAS<±20%，即SWAT模型对径流和总磷的模拟值均与实测值展现出较高的一致性.在流域尺度上，对总磷负荷的削减效率由高到低排序依次为：植被缓冲带>15°以上坡地退耕还林 > 有林地补植 > 化肥减施.宽度为1~5 m的植被缓冲带对总磷负荷的削减效率可达30%~48%；15°以上坡地退耕还林的实施可以削减约30%的总磷负荷，同时可能增加农民收入；然而，由于研究区土地利用格局和降水条件的特殊性，有林地补植和化肥减施对削减总磷负荷的影响较小，削减效率均不足1%.

Evaluation of best management practices (BMPs) for phosphorus load reduction based on SWAT model

Based on the high spatial resolution (0.07 m) land use and detailed agricultural management information, the reduction of non-point source phosphorus load was evaluated by applying best management practices (BMPs) to an agricultural watershed using SWAT (Soil and Water Assessment Tool) model. The results showed that the simulated values of SWAT model were highly consistent with the measured ones. The calibration results of runoff on all three hydrological stations achieved R² >0.5, NSE >0.4 and PBIAS <±35%, and two of them achieved R² >0.6, NSE >0.5 and PBIAS <±5%. In addition, the calibration results of phosphorus achieved R² >0.9, NSE >0.9 and PBIAS <±20%. On watershed scale, the reduction efficiency of total phosphorus load ranked as follows:Buffer strip > Returning farmland with slopes above 15° to orchards > Replanting under canopy > Fertilization reduction. The reduction efficiency of total phosphorus load for Buffer strip with width of 1~5 m were up to 30%~48%. Returning farmland with slopes above 15° to orchards can reduce total phosphorus loads by about 30% and may increase the profitability of farmers. However, due to the particular land use pattern and precipitation conditions, the efficiency of Replanting under canopy and Fertilization reduction was less than 1%.