| With the social development, human activities aggravate the water environment pollution, which leads to interconnected river system network (IRSN) function becomes weak, drought and flood disasters happen frequently, and other problems.The research of interconnected river system network (IRSN) becomes the urgent requirement for the river governance. Interconnected river system network (IRSN) has become the important topic of the research of the state river governance under the new situation. However, at present, about the theoretical research and technical methods of interconnected river system network (IRSN) still in the exploring stage,they are not formed the complete research system. In this paper, the author takes the Nandu River drainage basin as the example, according to the current situation and the water environment characteristics of the Nandu River drainage basin water system connection, the author makes the evaluation for the Nandu River drainage basin water system connection, and gives the suggestions and opinions targetedly, the main content is shown as below:(1) This article combined with the current basic national condition, summarizes The different scholars point of view, and explain the conception and connotation of IRSN, expound its inscape formulate the evaluation index system of IRSN, and in order to provide theoretical basis for in-depth study and practice of IRSN.(2)This paper established an IRSN system model for Nandu river , and analyze influencing factors, main driving factors and system variation law under the effect of these factors using system dynamics (SD) methods.We found that the main driving factors of the system include river frequency, degradation coefficient of pollutant,recycle rate of sewage, increase rate of surface water agricultural irrigation water supply, runoff guarantee rate of annual average and shortage rate of water. When,increase rate of surface water agricultural irrigation water supply was 5%, 10%, 15%and 20%, the percentage of surface water supply reached 94.27%, 94.83%, 95.34%and 96.98%.It will relieve the pressure on Nandu river water supply in the future if we use the trans-regional water drainage to improve the allocation of water resources and improve the recycle rate of sewage.(3) This paper construct the connection number of components between the evaluation samples and the evaluation criteria, the evaluation model (CN-AM) of IRSN is constructed. CN-AM model not only can measure the overall state of the level, but also can identify the important indicators of the system andsub systems.Application of CN-AM in Nandu River: In the next 5 years, the connectivity subsystems of the Nandu river system are 2.6976-2.6978, the natural function and social function subsystems are 3.5978-3.7403 and 3.6158-3.6920. The overall condition of the Nandu river system is 3.4625-3.5687,between the middle and the good.The main limiting indicators water connectivity, annual average runoff guarantee rate, water body pollutant capacity, river water quality compliance rate,surface water agricultural water supply percentage and so on.(4) In this paper,five water systems are developed to simulation by SD model and Use CN - AM model calculation, It is concluded that the next five years of the subsystems of IRSN in Nandu river , its development trend and the different periods of water system connecting link value and evaluation grades.It reveals the problems of IRSN in Nandu River Basin.We found that IRSN in Nandu River rating between the middle and good.In 2020, the ecological priority model (0.3322), the resource development model (0.3118), the flood control mode (0.3520) and the comprehensive development model (0.3966) were higher than the conventional development model(0.2003).Increase the water system connectivity,improve water efficiency,flood control safety project compliance rate and improve water pollution is a priority to consider the IRSN in Nandu River. |
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