| Shuangtaizi Estuarine Wetland, located in Panjin city in Liaoning Province, is the largest coastal reed marsh zone in China, which has played important roles in regulating regional climate, storing flood water, purifying water body, reducing pollution and maintaining water-salt balance, water-heat balance and water-sediment balance in regional ecosystem.However, with the impact of global climate change and human activities,the ecohydrological processes of estuarine wetland has changed dramatically and the ecohydrological pattern has been disturbed, resulting in wetland areas reducing, ecological water scarcity, water quality degradation, soil salinization, seawater intrusion and so on, which constrain the sustainable development of human society in the whole basin.In order to maintain a smooth development of the basin, protect and restore wetland, the paper studies ecohydrological regulation based on ecohydrological simulation of estuarine wetland under the changing environment and the main research results are as follows:(1)The watershed and wetland eco-hydrological modeling technology framework and simulation strategy are constructed based on the conclusion and summarization. According to the actual demand, the appropriate module are selected based on DGVM (Dynamic Global Vegetation Model), WEP (Distributed Hydrological Model) and SiB2 (A Simple Biosphere Model, Ver.2), and the ecohydrological simulation platform is built on the unified physical mechanism by coupling the different spatial and temporal scales.(2) The watershed-based information database, technically supported by ecohydrological simulation platform, combined with remote sensing and geographic information technology, was established and experienced by formating the input file, running, debugging and checking.The simulation results of the relative errors were controlled within 10%,the correlation coefficients were 0.76 or above, Nash coefficients are 0.7 or above except the Dongbaichengzi station in verified period of 0.57, basically meet the requirements.(3)Through the eco-hydrological simulation from 1981 to 2005 in Shuangtaizi Estuarine Wetland, the eco-hydrological evolution characteristics are analyzed.The results showed that:the change range of wetland ecological land is 78,300～92,500 ha, and the areas during the degradation period from year 1986 to 2000 decreased by 14,200 ha while increased by 400 ha in restoration period from year 2000 to 2005.The annual variation of ecohydrological elements (leaf area index, precipitation, evapotranspiration, runoff depth and natural supply water) shows a decreasing trend and the intraannual variation showed a single peak curve.The annual average natural supplement water of the wetland catchment is 6.35 billion cubic meters per year,8.32 billion cubic meters per year in the wet year,6.21 billion cubic meters per year in normal year, and 4.70 billion cubic meters per year in the low flow year.(4) Pursuant to the ecohydrological evolution characteristics, combined with the regional ecological protection positioning, determine the size of wetland sites under different satisfaction scales and make the appropriate area, planning area and the most residential area of ecological sites were 92,500 ha,93,300 ha and 77,200 ha, respectively; the ecological water demand were 3.46～18.77 billion cubic meters per year,3.89～21.13 billion cubic meters per year and 3.92～21.34 billion cubic meters per year. The water supply and demand analysis showed that:the water volume is adequate in wet years, which can meet the ecological water demand; the water volume in normal year can meet the minimum ecological water demand; in the low flow years ecological water shortages is serious, eco-supply capacity is 1.15-3.90 billion cubic meters per year. The ecological water demand can be meet after the appropriate ecological supplement regulation measures.
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