| Water resources can drives the development of human society,meanwhile it is affected by climate change and human activities.Water resources problems,such as the unbalance between supply and demand for water resources,water pollution,the degeneration of aquatic ecosystem,and so on,are more and more prominent.At this stage of scientific research,the further study of one water problem is valuable,but the comprehensive research considering various factors with water cycle as the ligament is more important.Supported by the National Grand Science and Technology Special Project of Water Pollution Control and Improvement(2014ZX07204-006),this study was carried out on the basis of water system scientific theory.Firstly,the key factor—environmental flow in water system was study further to recommend the environmental flow components of the study river,and the quantitative index of guarantee degree of environmental flow was proposed.Secondly,the comprehensive evaluation index system of water system health was structured,then the comprehensive indicators of water system health were calculated.Finally,the dynamic simulation model of the water system evolution was established based on system dynamics theory.Moreover,Huainan City in the Huai River Basin in China were selected for case study.The main work in this study includes:(1)The development and challenges of water system science were discussed.The main existing water problems and science research direction were provided.The research progresses on environmental flow,river health evaluation,water system science reviewed around the world.On this basis,the significance,research route and method of this study was put forward.(2)The theory,content,and method of water system were studied.The fundamentals of water system were clarified,and the study content and corresponding support methods were determined.The internal connection relationship of water system was analyzed.The water system covered five subsystems including hydrology,water environment,aquatic ecology,development and utilization of water resources,society and economy subsystems.The FLOWS method for environmental flow components calculation was improved.The composition model for comprehensive health evaluation of water system consist of compound fuzzy matter-element model,projection pursuit model,and chaotic particle swarm optimization algorithm was established.The system dynamic method was used to support the evolution analysis of water system,which could reflect the connection relationship within water system.(3)The key factor-environmental flow in water system was calculated and analyzed.Leiocassis longirostris,which was the special protected fish in the study river,was investigated.According to the ecological habits of Leiocassis longirostris,the corresponding hydraulic parameters and periods were identified.Then the improved FLOWS method was used to calculate the environmental flow components.In the migration period,the special environmental flow requirement was less than 1913.6m3/s.In the spawning period,the minimum environmental flow was 1307.0m 3/s,and it should occur at least once and extend over 7 days.The minimum environmental flow for larvae feeding period was 1037.9m3/s.The monthly basic environmental flows were calculated by the Tennant method for compensating the absence periods of the FLOWS method.The Guarantee rate of environmental flow(GEF)was put forward.Two kinds of GEF calculation methods were proposed:frequency analysis and satisfaction rate.The hydrologic frequency and duration curve of daily flow methods which belonged to frequency analysis category were selected to make case analysis.The hydrologic frequency method was used to analyze the annual average runoff from 1978 to 2012,and both the basic and optimal GEF in non-flood season were better,while the optimal GEF in flood season was between 70?80%.The duration curve was used to analyze the daily flow in 2007(wet),2008(normal),2011(dry),and GEF of 2007 and 2008 were better,but the optimal GEF in 2011 was 85.3%and in flood season of 2011 was only 20%.The GEF based on satisfaction rate and the environmental flow components of Leiocassis longirostris also used in 2007(wet),2008(normal),2011(dry)years.The results showed that GEF in different period of 2007 and 2008 was 100%,but in the migration and spawning periods of 2011,the GEFs were 82.0%and 65.3%respectively,and the continuous special environmental flow for spawning didn't occurred.(4)The comprehensive health of regional water system was evaluated based on the composition model.First the comprehensive evaluation index system was structured consisting of eight indexes:rate of flow change,DO concentration,comprehensive pollution index of water quality,treating rate of urban sewage,guarantee rate of environmental flow,rate of extreme low flow,rate of water resources development and utilization,and water consumption per unit GDP.The classification standards of each index was determined by policies and literature.Then the composition,model which composed of compound fuzzy matter-element model and projection pursuit model,was used to calculate the comprehensive indicators of water system health.The results showed that the maximum projection objective function was 0.3574.The minimum comprehensive indicator(0.030)was in 2006 Year which was at the level of sub-sick,and 2010 Year with the maximum comprehensive indicator(0.272)was at the sub-health lever.Other years were at the medium level.(5)The evolution of regional water system was analyzed by system dynamic method.The spacial and temporal boundaries of the SD model of regional water system were identified by the data information.Through analyzing the connection relationship within water system,the flow chart and SD structural equations of 47 variables were established.The historical validation from 2006 to 2014 showed that the overall simulation effects of the SD model was better,the absolute value of relative error of each evaluated variable was less than 10%.The results,compared with watershed planning in 2030 Year,showed that the simulation values were closed to the planning values,which indicated that the water system of Huainan City was increasingly catching up with the planning of the Huai River Basin. |
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