Analysis Of Runoff Change Based On Distributed Hydrological Modeling In Dongting Lake

Water resources conditions have significant evolved in China under the influence ofglobal climate change, development and utilization of regional water resources. With thedevelopment of society and economy, the water resources issues in Dongting Lake of droughtand floods are increasingly prominent in recent years, as it is the second largest freshwaterlake, and an important part of the Yangtze River in China. It is base of formulate thereasonable development strategy that to analyze the evolution, assess of possible futurechange trend of water resources in Dongting Lake. In this paper, a Distributed HydrologicalModeling is built to analyze the evolution of water resources in Dongting Lake. The maincontents and results are as follows：(1) To analyze the evolution trends of series of historical runoff in “Four Rivers” byM-K test and Morlet wavelet analysis. The results show that, it respectively occurs asignificant change in2002and1979in Xiang River and Li River, and it occurs onsignificantly mutation in Zi River, Yuan River and "Four Rivers" total flow. In the50years, itexists30~33years of the primary cycle, and it has a turned downward trend after2010ofrunoff in “Four Rivers”.(2) To establish a Distributed Hydrological Modeling in “Four Rivers” in Dongting Lakebased on SWAT, and calibrate and the test the model applied historical runoff data. It showsthat, in calibration period, Ensare higher than0.90in Xiang River and Yuan River,0.88in LiRiver, and0.75in Zi River. The performances are basically the same in validation period tocalibration period. It proves that the model is adaptable in Dongting Lake.(3)24kinds of scenarios of climate change are set up according to the projections offuture climate change to simulate runoff by SWAT, and to analyze the response of runoff andclimate change in Dongting Lake. The results show that, monthly runoff increases with theincrease of precipitation, and decreases with the increase of temperature; Influence ofprecipitation on the runoff is greater than temperature.(4) In the three periods of time of before the construction of the Three Gorges Project,the pre-impoundment period, and the official water after running, the average annual flowsignificantly reduced, however the average water level has no significant change trend inChenglingji; The official water after running of Three Gorges Reservoir, water resourcesexchange amount of Yangtze and Dongting Lake is194.8307billion m3, and it decreases than previous; The water amount of "Four Rivers" into Dongting Lake is less than the average formany years for10.31%.