SWAT模型水库模块改进及流域氮磷通量模拟

SWAT model reservoir module improvement and watershed nitrogen and phosphorus flux simulation

水库在发挥防洪、供水、航运功能的同时,也改变了库区和下游生态环境.现有的流域模型中水库模块相对简单,无法准确评估水库对河流氮、磷通量的影响.针对这一局限性,本研究从蓄泄规则、库区氮磷反应模拟两个方面改进了经典流域模型—SWAT模型的水库模块.以长江二级支流涪江流域为研究对象,模拟了水库建设对逐月流量、泥沙、总氮、总磷过程的影响.结果表明,新模型模拟的逐月流量、泥沙、总氮、总磷的绝对误差百分比从原来的41.1%、33.4%、99.0%、130.5%分别降低到8.6%、23.9%、38.4%、52.9%,在汛期6—9月总磷的平均模拟误差仅为12.1%.新模型合理刻画了梯级水库群的级联效应,提高了梯级水库影响下的河流氮、磷通量模拟能力,为流域水环境管理与水库调度提供了有效工具.

In addition to serving as a source of water,flood control facility,and navigational aid,the reservoir has impacted the natural environment of the reservoir area and downstream.The current hydrological and water quality models in the basin have a rudimentary reservoir module,which cannot accurately analyze the reservoir's impact on nitrogen and phosphorus fluxes in the river.Therefore,this study enhanced the reservoir module and two features of the SWAT model:water quantity and quality.The study simulated monthly discharge,sediment,total nitrogen,and total phosphorus processes from 2008 to 2019 in the Fujiang watershed,the second tributary of the Yangtze River.The results show that the relative errors of monthly discharge,sediment,total nitrogen,and total phosphorus using the new model are reduced from 41.1%,33.4%,99.0%,and 130.5%to 8.6%,23.9%,38.4%,and 52.9%,respectively,and the average simulation error for total phosphorus during the flood season(June to September)is only 12.1%.The novel model is a useful tool for watershed water environment management and reservoir operation.It accurately reflects the cascade effect of cascade reservoirs and enhances the simulation ability of river nitrogen and phosphorus fluxes under the influence of cascade reservoirs.