The Study On Water Quality For Mid-lower Reach Of Hanjiang River Of Middle-route Of South-to-North Water Transfer Project

Middle-Route of South-to-North Water Transfer Project is the important Part of South-to-North Water Transfer Project. It is important for solving the water shortage in Beijing, Tianjin and the other area of North China. It also improves the ecological environment of diverting area, and the economical and social situation of diverting area. The Mid-lower Reaches of Hanjiang River is not only the important water source of all cities along Hanjiang River, but also has critical function. However, after Middle-Route of South-to-North Water Transfer Project putting in practice, the geographic distribution of the water resource will be changed and the water quality and ecological environment of diverted area in the Middle and Lower Reaches of Hanjiang River will be impacted deeply .This paper built the one-dimension water quality model and study the water quality change of mid-lower reach of Hanjiang river, which is affected by middle-route of south-to-north water transfer project. The main contents of this paper are listed as follows:Firstly, in this paper, the hydrological features and the water pollution situation was obtained from hydrological and water quality data of decades. This study also predicts the point source pollution loading using the industrial production index model; As far as non-point source pollution is concerned, based on Remote Sensing and Geographical Information System, considering the impact of population and economic development and land use on non-point source pollution load, non-point source pollution has been assessed in the mid-lower reaches of Hanjiang River by the Rainfall and Run-off model, pollution empirical model and pollutant transference-output model. The non-point source pollution loading is calculated quantitively, and this may offer fundamental data and proof for water quality prediction.Secondly, the point and non-point source pollution and branch confluence are considered with one-dimensional water quality model. The model is validated by the hydrological data and the index measured data of COD_Mn from 2000 to 2002, and relative errors are less than 29%. The results indicate that this model can be used for water quality simulation. Before and after the 9.5-billion m~3 water transfer, simulation of water quality on different hydrological and water pollution loads condition are carried out in themid-lower reaches of Hanjiang River, respectively.Thirdly, considered on non-point source pollution of watershed, environment capacity model is developed, which is based on the two-dimensional water quality method. The model is then calculates quantitively the affect of the middle route project of the south-to-north water transfer on the mid-lower reaches of Hanjiang River from the point of environmental capacity.