农业管理措施对三峡库区流域非点源污染削减效果评价

Reduction effects of agricultural management practices on non-point source pollution in a watershed in Three Gorges Reservoir Area

选取三峡库区典型流域,利用已校准的连续非点源污染模型AnnAGNPS,评价作物种植、化肥施用水平和3组农业管理措施(保护性耕作措施,CTP;保护性工程措施,CRP;退耕还林措施,CCFP)对农业非点源污染(NSP)输出的削减效果.模拟结果表明:作物种植类型对泥沙削减的效果差异不显著,对磷输出削减的效果差异显著;化肥施用量对总氮和总磷输出影响极显著;CTP可以显著削减泥沙输出,增加养分输出;CRP能削减泥沙输出,对养分输出削减的效果不显著;CCFP对泥沙和养分输出削减效果均显著,坡度>10°农田实施CCFP后,流域泥沙输出<5t.hm-2,氮、磷等养分输出量可降低至容许范围.

Taking a typical watershed in the Three Gorges Reservoir Area （TGRA） as test object,the AnnAGNPS model was used to evaluate the reduction effects of different cropping,different fertilization level,conservation tillage practice （CTP）,conservation reserve program （CRP）,and conversion of cropland into forestland program （CCFP） on the output of agricultural non-point source pollution （NPS） in the watershed. The simulation results showed that different cropping had no significant difference in the effect of reducing sediment yield,but had significant difference in the effect of reducing phosphorus output. Fertilization level had significant effects on the outputs of total nitrogen and total phosphorus. CTP decreased the sediment yield significantly but increased the nutrient output. CRP reduced sediment yield,but had less effect in reducing nutrient output. CCFP reduced both sediment yield and nutrient output significantly. After the implementation of CCFP,the sediment yield output on the croplands with a slope greater than 10° was less than 5 t·hm-2,and the nutrient output was within the permissible limit.