流域非点源污染模拟研究--以滇池流域为例

流域的水质管理是一个多步骤的过程,数学模型以其定量计算和动态操作在流域管理中起着重要作用。本文利用美国EPA开发的HSPF(HydrologicalSimulationProgramFortran)模型,选取云南滇池流域作为案例,给出非点源污染模型流域水文水质的模拟过程。首先在子流域划分的基础上,完成数据库的建立。参数估值主要依据流域性质、先前经验值、其他模拟研究和文献中的取值。参数优化、模型校正和模拟验证是采用流域河流出口流量和污染物浓度值完成。最后用校正后的模型计算了滇池流域河流入湖流量及各子流域污染总负荷量与非点源污染负荷量。

Simulation of non-point source pollution in watershed scale: the case of application in Dianchi Lake Basin

Watershed water quality management is a process with many steps. Mathematical model plays an important role in watershed management as it can resolve the problem quantificationally and be operated dynamically. HSPF (Hydrological Simulation Program Fortran) developed by USEPA was chosen for the application in this paper. Hydrology and water quality simulation processes in the non-point source pollution model were introduced in the study, in which Dianchi Lake Basin was chosen for the case study. The whole basin was divided into nine sub-basins firstly. Then the non-point source database for the Dianchi Lake Basin was built. Sensitivity analysis revealed that only a few parameters were sensitive to the simulation of runoff and water quality processes. In the paper, the simulation processes for river outflow, SS, BOD, TN and TP were introduced in detail. The simulation processes for Panlongjiang Sub-watershed was given as an example. Parameter values were estimated from watershed properties, previous experimental and modeling studies, regional field studies and literature. Optimization of the parameter values, calibration of the model and validation of the simulation was achieved using stream flow and concentration of pollutants in the river outflow of watershed. The simulation results showed that relative error for runoff simulation in some sub-watersheds was very small. On the whole, the runoff simulation results were good. After that, the total and non-point source pollution loads of SS, BOD, TN and TP in each sub-watershed were calculated using the calibrated model. The results revealed that the main contributors of the non-point source pollution in the Dianchi Lake Basin were SS, TN and TP. From the spatial distribution to the non-point sources, nitrogen pollution mostly came from Panlongjiang, Baoxianghe and Chaidahe sub-watersheds. It could be attributed to the large amount usage of fertilizers in agricultural lands. SS and TP pollution status was serious in Chaidahe sub-watershed and western diffused area. The main reason could be explained as many phosphorite mines were distributed in such areas. High water and soil runoff and phosphorous adsorption had caused high non-point source pollution in total phosphorous.