The Effect Evaluation of Pollution Flushing for Improving Water Quality in Wenruitang River, China

摘要

Flushing the contaminative rivers or lakes with clean water from reservoirs or rivers has been a common pollution treatment practice in China. In order to evaluate its environmental benefits, project cost and the amount of the pollutant migration of flushing the Wenruitang River, searching for a best pollution flushing discharge, this paper, by using the hydrodynamic and transport model, puts forward and applies local environmental benefits (the environmental benefits of local river) and global environmental benefits (the environmental benefits of global river which contains the local river and its downstream) to estimate the different effect of flushing pollutants to local river and global river including the local river and its downstream, and makes a comparison with the project cost to analyze the feasibility. The simulation result indicates that the water quality improvement of local river is mainly caused by pollutant migration rather than the increase of degradation ability, but for the global river, the pollution flushing also has obvious environmental benefits. What's more, with the increase of pollution flushing discharge, the increase amplitude of environmental benefits decreases rapidly and is less than that of the whole project cost, therefore, larger flushing discharge does not always mean greater benefits. As to the Wenruitang River, the appropriate pollution flushing range is 29 to 108.4 m3/s, with the best flushing discharge being 66.05 m3/s.