Study On Water Environmental Capacity Of Fujiang River In Mianyang Downtown Segment

Water environment capacity is a basic theory of environmental science, which reflects the principles of pollutant migration and deposit in water environment and reflects the environment tolerance in the particular function. In practice, water environmental capacity is the basis of environmental objective management and a main constrained condition of district environmental planning as well as the key technique of the total water pollutant control.As a kind of resources, the water environment capacity has not only the characteristics of natural resources, but also its own characteristics. This paper has in detail reviewed the basic theories on water environment capacity and river water environment capacity calculation models, and has analyzed the reasons for keeping sustainable development and the total water pollutant control to research water environment capacity; with collecting a large quantity of environmental monitoring data, surveying data and hydrologic data, the paper has researched the river water environment capacity of Fujiang river in Mianyang downtown segment( Fujiang river and its subsidiary current Anchangjiang river ) and provided the scientific basis for the engineering manage synthetically for Liangjiang river valley and the water resources management. This research primarily includes four parts:1. Water quality evaluationThis text first put up the assessment of present water quality of the surface water in Mianyang City using the contaminative synthesize index number method and analyze the monitoring data from 1993 to 2002,the result indicates that the surface water had been contaminated in different degrees. The main contaminations are organic types, the main contaminative criterion are Chemical Oxygen Demand and Biochemical Oxygen Demand. They are both exceeded the standards of Environmental Quantity Standard for Surface Water(GBZB l-1999).The all segments are accord with the Third degree of surface water environment quantity standard except Anchanging river and Lijiadu segment of Fujiang river that had been severity contaminated.2. Water area functional compartmentalizationAccording to water function of different river segments that the social economic development and the environmental protection requests, the surface water in Mianyang City including Fujiang river and Anchangjiang river is decides into two main types and six segment functional districts: the drinking area and the fishing area that are compared by ShunHe segment and give attention to the other and lower function at the same time.3. Water environment capacity calculationThis text make sure the biggest admission for water environment for each river segment, and respectively compute the Water Environmental Capacity of each segment of Fujiang river from 1993 to 2002 by head control computing model. Since 1997, the water quality have been getting improvement, the water environment capacity immediately enlarge. Those fundamental attain a level numerical value and all over above 3000 tons/ years jn 2002.4. Application for water environment capacityValue of Water Environment Capacity is a deal's function of nature, society, economy and technology. According to the two-section dispose of organism water, this text compute out the value of water environment capacity in Mianyang downtown segment of Fujiang river, and provide consult to make use of the water environment capacity in reason.