The Hydrological Response To Land Use Change Scenarios In The Upper Reaches Of The Fu River Basin Based On SWAT Model

Based on the DEM(Digital Elevation Model)?LUCC(Land-Use and Land-Cover Change)?soil and climate data of the The upper reaches of the Fu He river Region,The SWAT model were builed by RS(Remote Sensing)and GIS(Geographic Information System)in this study.In order to provide a reference for the optimization of land use and the prevention of flood disaster in the upper reaches of the Fu River,two land use scenarios of the year of 1995,2005,2015 and four hypothetical land use scenarios:Closed forest,Vegetation degradation,Grassland,chersic were setted up to study the response of surface runoff under different land use situations.The main results were presented as follows:1?During 1995 and 2015,The area of woodland had shrunk,showing a slow increase and a decrease in the trend.And The final area is reduced.The area of water and construction land continued to increase,and the construction land area was enlarged greatly,while a small amount of the land area was showing and changing little.In terms of spatial distribution,arable land was mainly distributed in the height of 200m,and the slope distribution is mainly flat and gentle slope.The area distribution of cultivated land in higher elevation and steeper slope was increased during the period.The woodland was mostly in the slow slopes below the 400m.With the increase of area,the construction land and water area wera aggregated in the height of 200m and the latter is gathered in 200m-400m.The area of grassland increased only in the height of 200m.2?The river basin was divided into 40 sub-basins and 486 hydrological response units.The results of parameter sensitivity analysis showed that CN2,ALPHA-BNK,ch-n2,SFTMP,gw-delay and GWQMN were the six parameters that contributed the most to runoff simulation results.Efficiency coefficient(Ens),determination coefficient(R~2),relative error(Re)were selected as model applicability evaluation standard.In 1995-1999,the scale of the simulation of the model was a class a,and the three coordinates were:0.9,0.91,and-6.9%.During the validation period from 2000to 2004,the model level was class b,and the three indexes were:0.89,0.88 and 1%.The simulation results are good enough to meet the model requirements.3?The current land use type scenario simulation results show that the runoff in the basin was increasing in 20 years.It was indicated that the annual runoff depth of grassland,arable land and wasteland was increased compared with that of the basic land use,and the depth of the forestland was decreased.The forest conservation index was 0.222,which had the strongest water conservation ability,followed by grassland.Compared with the basic land use scenario,the total runoff of the forest land was increased and the flood season was reduced compared with the original situation.The total runoff depth increased significantly in the dry period and during the period.Forestland made a contribution to reduce annual runoff,water conservation and adjust annual runoff distribution.