Simulation The Runoff Of Ungauged Basins In Coastal Zone Of Liaoxi Corridor Based On SWAT Model

Coastal zone of Liao-xi corridor locates in the west of Liaoning province.The water resource in this area is 1/4 of the Chian average,and it is an area with severe water shortage.However,Runoff of many independent rivers into the sea has not been fully utilized,flowing into the sea wastely.The contatdictions between shortage of water resource and lowly utilization of water resource is striking.Buliding an groundwater reservoir in valleys of independent rivers into the sea is of great significance for alleviating the pressure of water resource and achieving sustainable utilization of water resource.As an important supply resource of groundwater reservoirs,the independent rivers into the sea are mostly ungauged rivers.Therefore,Carrying out runoff simulation of ungauged basins in typical coastal valleys can provide the precondition and foundation for groundwater reservoirs construction.Liuguhe river (a reference basin) and dog river(an ungauged basin) as the research object,the runoff of dog river ,as well as hydrologic impacts of climate changes and land use changes,are studied.Based on the comprehensive analysis of demestic and overseas runoff simulation in ungauged basins,the hydeological similarity of catchments between liuguhe river (a reference basin) and dog river (an ungauged basin) is studied,and runoff of ungauged basins is simulated with the SWAT model parameters transplating method.As the same time, hydrologic impacts of climate changes and land use changes are studied.The runoff simulation database of SWAT model is constructed by collecting meteorology,hydrology,land use,soil and other basic data of the study area.The model databases include spatial databases and attribute databases.The spatial model databases are DEM with resolution of 90 meters,siol map(cinnamons soil,meadows soil,browns soil) and land use map(past,forest,dryland,paddy filed,construction land).All of the spatial databases realize the distributed description of spatial information about SWAT model.Tttribute databases of the model includes soil databases,land use databases,meteorological databases.The soil parameters of siol databases are mainly adopted from the"Liaoning province soil collected works"and field investigation. Soil texture is converted into American criterion, hydraulic conductivity and soil moisture content are worked out. The parameters of land use are related to two databases of SWAT, Land Cover/Plant Growth Databases and Urban Databases.The meteorology databases are derived from eleven precipitation gauging stations and four evaporation gauging stations in study area.According to the model parameters transplanting method,A reference basin which its parameters are transplanted to ungauged basin is needed in order to simulate runoff of the ungauged basin-the dog river. As to transplant parameters between two basins, Hydrological similarity of catchments is evaluated according to the factors affecting runoff. It is showed that hydrological similarity exits in a reference basin and an ungauged basin. Therefore,model parameters of the reference basin can be transplanted to the ungauged basin.In order to get SWAT model parameters of Liuguhe river, Eight parameters influencing runoff are choosen to be modified based on the observed runoff data from the year 1990 to 2000 from Suizhong gauging station,including the curve number of SCS model CN, the available water of soil SOL_AWC, the saturated conductivity coefficient SOL_K,the delay time the groundwater recharge GW_DALAY, groundwater evaporation coefficient GW_REAVP, the decline coefficient of base flow ALPHA_BF, the compensating coefficient of soil evaporation ESCO and the max/min velocity of snow SWFMX/SWFMN.After calibration and validation for model parameters,the model simulation accuracy meets the requirements of research and also it shows that applicability of SWAT model in this area.Based on SWAT model of the ungauged basin-dog river, the runoff of the dog river from the year 1996-2006 is simulated by transplanting model parameters of Liuguhe river to the dong river. In order to study hydrological response of climate change, Assume climate situation method is selected.Precipitation is set on the original basis of an increase of 10%,a reduction of 10%,and unchanged;Temperature is set on the original basis of an increase 2℃,a reduction 2℃,and unchanged.There are total nine climate change composite.The result of simulating shows that runoff increases with the increase of precipitation and decreases with the increase of temperature.However, Precipitation imposes more impact on the runoff than temperature.In order to study hydrological response of land use change, Four sceces are seted namely forest degradation, forest increase, covered wholely with past and covered wholely with forest. Simulation result shows that runoff increases with the forest increase. As to effects on water conservation and runoff reduction, Afforestation is better than grass planting.Runoff of the ungauged basin-dog river basin in Liaoxi corridor coastal zone is simulated. It not only can offer technology demonstration and research support when such study is carried out in similar areas,but also can provide prerequistite and foundation for building groundwater reservoirs.