Water Quality Evaluation Research Of Water Function Areas In The Yangtze River Downstream Based On GIS

The water is not only the indispensable natural resources for human survival, but also the environmental resource that the creatures for survival. With the rapid development of Chinese economy, and the problems of water resources have become increasingly prominent, these have serious threats to the ecological environment and the sustainable development of social economy. Therefore, it is imperative to strengthen the protection of water resources, establish and improve the water quality warning system and make scientific assessment on the water environmental quality. Through the water environmental quality assessment, it can effectively reflect the real water quality and changes, to provide effective information for river management, this assessment is an important part of environmental decision-making and supervising management of water services.Based on the general information system, GIS provides spatial data management and analysis technology. Applying GIS to the assessment of river water environmental quality, using its powerful data storage, analysis, processing, graphical display and spatial analysis ability to establish the system of river water quality assessment. This paper based on the basis of GIS technology, we try to evaluate the water quality of water function areas in the Yangtze River by combing the GIS technology and scientific water environmental quality assessment methods. Based on this, the thesis mainly do the following several aspects work:First, study the current water quality assessment methods in common use and its theory, and collect the information about the environmental status of Yangtze River water function areas and the divisions about the water function areas in the Yangtze River downstream. By comparing and studying the regional environmental work, we determine the water quality identification index as water quality assessment method. Meanwhile, the thesis select the five indicators (dissolved oxygen, permanganate index, BOD5, ammonia nitrogen, total phosphorus) to evaluate the water quality of water function areas.Second, this thesis design and develop the water quality evaluation system of Yangtze River downstream which is based on GIS platform Visual Basic. This system could achieve some GIS functions which are water quality data management, GIS thematic mapping capabilities, statistical analysis and water quality assessment. Meanwhile, it provides data visualization function for water management decisions of the water function areas in the Yangtze River.Third, using the developed water quality assessment system to evaluate the water quality of water function areas of Yangtze River downstream. Meanwhile, based on the results of analysis and evaluation and proceeded from the environmental status of water function areas, this thesis propose appropriate environmental management measures and countermeasures to provide the basis for future management decisions.This paper proceeding from reality, combing the theory of water environmental quality assessment and GIS technology, so this research conform to practical application, give the future about management and decision-making of river resources to better support.