基于改进的SWAT模型农业面源污染变化规律数值模拟——以赣抚平原灌区芳溪湖小流域为例

Simulation on Variation Regularity of Agricultural Non-point Source Pollution by Modified SWAT Model: A Case Study of Fangxi Lake Small Watershed of Ganfu Plain Irrigation District

以赣抚平原灌区内的芳溪湖典型小流域为研究区域,基于改进的SWAT模型,针对典型水文年年内不同降雨条件,模拟灌区氮磷面源负荷的迁移规律,同时对灌区农业面源污染负荷流失量的空间分布规律进行了模拟分析。结果表明,降雨是氮磷负荷流失的主要驱动因子,氮磷流失量随降雨的波动而变化,并与降雨同步达到峰值。因此,在灌区需加强汛期田间水肥管理,以减少氮磷的流失,提高肥料的利用率;在相同降雨条件下,研究区氮、磷负荷流失量空间分布差异较大,呈现出水系上游流失量多下游流失量少的趋势;在防控和治理灌区面源污染时,可适当考虑面源污染的空间分布规律,采用沿途生态沟渠和湿地对灌区内的面源污染负荷进行稀释和净化,以达到减轻和治理面源污染的效果。

The modified SWAT model is applied to simulate nitrogen and phosphorus migration and spatial distribu-tion for Fangxi Lake watershed in Ganfu Plain Irrigation District of Poyang Lake Basin in different rainfall events of typical hydrological year.Results show that rainfall is the main driving force of nitrogen and phosphorus losses.Ni-trogen and phosphorus losses fluctuate with rainfall event,and their peak values almost synchronously occurr. Therefore,it is very important to optimize the farming management methods in flood season to control non-point source pollution,and to improve the application rate of fertilizer.The spatial distribution of nitrogen and phosphor-us losses has much differences,nitrogen and phosphorus losses are higher in the upstream than in the downstream of the study area.Therefore,the spatial distribution of non-point source pollution can be appropriately considered in pollution prevention and control,and ecological restoration techniques as ecological ditches and wetlands applied a-long the water pathway can be considered to purify and dilute the pollutants.