Simulation and control of non-point source pollution based on MIKE model: A case study of Danjiang river basin, China

Abstract

In the world, non-point source (NPS) has become one of the important factors affecting the water environment and water ecological security in the basin. In this paper, we investigate the response of runoff to pollution loads by establishing the MIKE SHE and MIKE HYDRO River coupled model with the Danjiang river basin as the research object; The MIKE LOAD is used to analyze the spatial and temporal distribution characteristics of agricultural NPS pollution and to perform equivalence load analysis of pollutants in the basin; Single and combined control measures are set up to simulate the reduction effect of each pollutant for NPS pollution control in the basin. The results show that daily runoff has a high correlation with daily pollution loads of ammonia nitrogen (NH₃-N) and total phosphorous (TP); The pollution load of Jingziguan section calculated by the coupled model is comparable with the results calculated by MIKE LOAD, and the relative error is below 30%, and the simulation results are reasonable. The trend of the load into the river for all pollutants is consistent with the rainfall and generally shows the characteristics of high loads in flood season and low loads in non-flood season. The total emissions of NPS pollutants in the basin are TN>NH₃-N>TP>COD, and the loads share of the four pollutants are 52.82%, 21.31%, 19.42% and 6.44% respectively. Four single and one combination measures are set up to evaluate the pollutant reduction effects. The reduction effect of combined measures is significantly better than that of single measures.