Water quality model establishment for middle and lower reaches of Hanshui River, China

With the development of industry and agriculture, nitrogen, phosphorus and other nutrients in the Hanshui River greatly increase and eutrophication has become an important threat to the water quality of the Hanshui River, especially in the middle and lower reaches. The primary objective of this study was to establish the water quality model for the middle and lower reaches of the Hanshui River based on the model of MIKE 11. The main pollutants migration and transformation process could be simulated using the water quality model. The rainfall-runoff model, hydrodynamic model and water quality model were established using MIKE 11. The pollutants, such as chemical oxygen demand (COD), biochemical oxygen demand (BOD), ammonia nitrogen, nitrate nitrogen, phosphorus, dissolved oxygen (DO), were simulated and predicted using the above three models. A set of methods computing non-point source pollution load of the Hanshui River Basin was proposed in this study. The simulated and observed values of COD, BOD5, ammonia, nitrate, DO, and total phosphorus were compared after the parameter calibration of the water quality model. The simulated and observed results match better, thus the model can be used to predict water quality in the future for the Hanshui River. The pollution trend could be predicted using the water quality model according pollution load generation. It is helpful for government to take effective measures to prevent the water bloom and protect water quality in the river.