基于SWAT模型的清凉山水库氮磷入库通量研究

Study of Nitrogen and Phosphorus Inflow Fluxes into Qingliangshan Reservoir Base on SWAT Model

以清凉山水库流域为研究对象,构建SWAT模型模拟计算入库流量与氮磷通量,分析氮磷时空分布特征与潜在空间来源。研究表明:清凉山水库多年平均入库流量为2.77 m^(3)/s,总氮、总磷入库通量分别为33 030.3、2 282.0 kg/a,经新田水的总氮(19 882.7 kg/a)、总磷(1 275.4 kg/a)入库通量高于经溪田水的总氮(12 977.5 kg/a)、总磷(956.9 kg/a)入库通量;汛期的氮磷入库通量大于非汛期,水体中总氮、总磷浓度均在入汛前达到峰值;总氮、总磷负荷较大的区域主要分布在流域中部地区,总氮负荷集中于农田占比高的地区,总磷负荷集中于铁质强淋溶土占比高的地区;流域中氮素的主要来源是农业施肥,磷素的主要来源可能是自然源。研究成果可为流域内水环境管理提供科学依据。

Taking the Qingliangshan Reservoir Watershed as the research object, this study builds a soil and water assessment tool(SWAT) model to calculate reservoir inflow and nitrogen and phosphorus fluxes by simulation and thereby explore the spatio-temporal distribution characteristics and potential spatial sources of nitrogen and phosphorus.The following observations can be made from the results.The multi-year average inflow into the Qingliangshan Reservoir is 2.77 m^(3)/s, and the total nitrogen(TN) and total phosphorus(TP) inflow fluxes into the reservoir are 33 030.3 kg/a and 2 282.0 kg/a, respectively.The TN and TP inflow fluxes of the Xintian tributary(TN:19 882.7 kg/a;TP:1 275.4 kg/a) into the reservoir are higher than those of the Xitian tributary(TN:12 977.5 kg/a, TP:956.9 kg/a).The nitrogen and phosphorus inflow fluxes in the flood season are also higher than those in the non-flood season, with peak concentrations of TN and TP in the water both observed before the flood season.Large TN and TP loads are mainly distributed in the central area of the watershed. Specifically, the TN load is concentrated in areas with a high proportion of agricultural land, while the TP load is concentrated in areas with a high proportion of Ferric Acrisols(ACf).The nitrogen in the watershed primarily comes from agricultural fertilization, whereas the phosphorus possibly comes from natural sources.The results provide a scientific basis for the management of the water environment in the watershed.