Study On Trans-boundary Section Water Quality Of Min Jiang Area In Le Shan City

Today in China, the rivers’quality of an area may not reach its target, and worse transfers to the downstream, even the area reaches its standard of pollutants discharge. As a result, controlling the total volume of pollutant discharge is a must. Based on the fact that controlling the total volume of pollutant discharge is calculated on the assimilative capacity of rivers, reducing the total volume and allocating the volume that were cut down can let the river successfully achieve its target. How to define the responsibility plays an important role in trans-boundary section water quality study:the reason that water quality of downstream of trans-boundary section cannot reach its target may lies in the upstream while the downstream had already achieved it. The condition of trans-boundary section water quality affects the economic and social development on Leshan District because the three branches of Min Jiang river, such as Min Jiang river in Le Shan City、Qing Yi river、Da Du river, run through every corner of Le Shan District. Forecasting trans-boundary section water quality provides ideal management and control for related governmental department. It brings higher attention from the government and thus becoming more important.In my thesis, by collecting academic references and on-site data, I tried to find a proper method for trans-boundary section water quality to evaluate the three branches of Minjiang Water of Leshan District. Fisrstly, by analyzing the maximum assimilative capability of the river in terms of the assimilative capacity, I found out that the water quality of Ma’an mountain-Lao Jiang Ba of Min Jiang downtown and Shui Yin Ba-Long Xi Kou of Qian Wei County had already exceeded its assimilative capacity. Secondly, forecasting the future pollutant by my resources, I found out that Guan Di Miao-Ma’an mountain, Huang Shui Ba-Lao Ba Zi of Minjiang River, and Shui Yin Ba-Long Xi Kou of Qian Wei County had exceeded it capacity of the assimilative capacity of rivers. Then I calculated the reduction quantity of pollutant by contrasting the condition of pollutant discharge and the assimilative capacity of rivers of the river, and concluded the best way of point source pollution and non-point pollution reducing at the same time by forecasting the future water quality of the river. In the end, accordingly, I proposed the solutions and suggestions on drain outlet control、point source pollution and non-point pollution management and trans-boundary section water quality control.