参数空间分布对非点源污染模拟的影响

Effects of Parameter Spatial Distribution on Non-point Pollution Source Model

以大宁河流域为研究区域，应用非点源模型SWAT（soil and water assessmentt001），模拟了参数空间分布对流域径流和营养物质流失的影响．利用大宁河流域巫溪水文站，2000～2004年的实测数据对模型进行了率定和验证，将流域划分为6种数量不等的子流域，利用相同的模型参数输入，模拟了不同的流域划分方案对径流和营养物质流失的影响．结果表明，不同的流域划分方案，年平均流量的最大相对误差为19．6％，6种方案年平均流量的效率系数为0．52～0．82，月平均流量的效率系数为0．80～0．83，随着子流域数量的增加，径流量出现了先下降、后上升的趋势；有机氮和有机磷的最大相对误差分别为16．2％和7．7％，不同的流域划分方案对营养物质的流失产生了轻微的影响，但没有明显的变化趋势和规律．

The SWAT model was used to simulate the effects of parameter spatial distribution on flow and nutrients loadings in the Daning river watershed. It was first calibrated and validated using the measured data for the period of 2000 - 2004. Then the model was used to simulate the effects of watershed delineation scenarios on flow and nutrients loadings, using six watershed delineations, each with a different number of sub-watersheds. The max relative error is 19.6% for the annual mean flow under different watershed delineation scenarios. The flow increase first and then decrease with the number of sab-watersheds. The efficiencies coefficient is 0.52 - 0.82 for annual mean flow and 0.80 - 0.83 for monthly mean flow under six delineation scenarios. Outlet nutrients simulations are slightly affected by changes in watershed delineation scenarios. The relative errors of organic nitrogen and organic phosphorous are 16.2 % and 7.7 % respectively and no exphcit trend is observed.