River Water Quality Simulation And Total Pollution Control

The rapid pace of economic growth and social development in China has brought great pressure to the water environment of the river basin,threatening the safety of the ecological environment.Therefore,water environment governance and management have become one of the most critical concerns facing the national water conservancy development.In recent years,a number of studies and engineering practices have been conducted for water environment governance and pollution control at home and abroad,including pollutant load estimation,pollutants migration and transformation simulation,water environmental capacity estimation and pollution control schemes.However,few studies have really focused on a full range of comprehensive analysis from load estimation,water quality simulation,pollution source attribution,water environmental capacity,finally to the pollution control scheme.Therefore,a case study of Dengsha River Basin in Dalian,Liaoning is analysed,where the water is scare and polluted,and has an urgent need for improving the water quality and strengthening the water environment management.Pollutant loads from multiple land-based pollutant sources are estimated,and then the QUAL2K model is applied to simulate the migration and transformation of ammonia nitrogen and total phosphorus.With the aid of the model,this study further identified the relative contribution from each pollution source at both the temporal and spatial scales.Finally,water environment capacity is calculated and suggestions of water pollution control and reduction are proposed.With the above analysis,this study would be a great support for informed decision-making in water environment governance and management.The main achievements of this study are as follows:?1?On the basis of field monitoring and data collection,the water quality indexes are analyzed and evaluated to understand the situation of the water environment in the Dengsha River.The ammonia nitrogen and total phosphorus are of the major excessive factors and are therefore selected as target pollutants in this study.?2?Facing with the water quality deterioration problem,the pollutant loads?i.e.,ammonia nitrogen and total phosphorus?yielded by various land-based sources,including industries,animal feedlots,agricultural planting,rural households and natural soil erosion are calculated to identify the source and composition of pollutants.In addition,pollutant loads from rural households and agriculture are also calculated based on the remote sensing data,which can be applicable for pollutant load estimation in data-lacking regions.?3?To fully understand the impact of terrigenous pollutant load on the water quality in the main river,the QUAL2K model was applied to simulate the in-stream pollutant transport and retention processes.Model parameters were calibrated to the observed water quality data.The satisfactory agreement between the simulated and observed data have suggested that the model is capable of simulating the transportation and migration of NH₃-N and TP in the Dengsha River.Further,the model is applied to quantify the relative contribution of each pollution source to the river water quality variation in both temporal and spatial scales.Results indicated that animal feedlots and natural soil erosion are major contributors to NH₃-N and TP loads,respectively.In addition,the contribution of each pollution source varies among different months within the year.?4?With the aid of QUAL2K model,the environmental capacity of NH₃-N and TP loads from the upper and lower reaches are calculated at the annual and monthly scales based on the trial and error method.The suggestions for local water pollution control and governance are proposed.