Impacts Of Human Activity On The Hydrological Process Of Jinjiang Catchment Based On The Simulation Of SWAT

The landuse change impacts evaporation,surface runoff,infiltration,groundwater,and eventually lead to runoff change.Reservoir operation including upstream water interception,water diversion and storage function will affect the downstream channel runoff.It is meaningful to reveal human activities impact on hydrology processes through the analysis of hydrological processes response to landuse change and reservoir operation.Jinjiang catchment is located in the south-eastern coastal region of China with rapid economic development,and significantly human activities including landuse change and reservoir operation.We choice Jinjiang catchment as study area to analysis the hydrological processes response to human activities,which could provide scientific reference to land use management,water resources allocation,reduce the flood control and drought disaster,and ecological environment governance.The research simulated the impacts of landuse change on evaporation,surface runoff,soil infiltration,groundwater and channel runoff by SWAT model for nine years(2002-2010),under the same meteorological inputs but two different landuse scenarios(1985 and 2006).In addition,the yearly,monthly and daily extreme runoff response to Shanmei reservoir operation was simulated by SWAT model.The results as following:(1)When the land use changed by increasing impervious area(urbanized,orchard)and decreasing in the good water conservation area(forest,grassland,farmland)from 1985 to 2006,which resulted in reducing mean yearly evapotranspiration,soil percolation and groundwater by 2.57%,7.54%and 11.48%,respectively.On the contrary,the change of land use from 1985 to 2006 increasing mean yearly surface and channel runoff by 14.89%and 2.25%,respectively.(2)Changes in monthly hydrological processes due to landuse change varied from month to month.In the dry season,monthly evapotranspiration decreased significantly,however,surface runoff increased significantly.Soil percolation and groundwater have the similar change trend,which decreased in all the year and have the positive with precipitation.Monthly channel runoff decreased in the early dry season,and then increased in the other months.(3)Shanmei reservoir operation have a little influence on hydrological processes,which decreased yearly surface runoff and channel runoff by 3.32%and 0.51%,and increased yearly soil percolation and groundwater by 5.67%and 7.91%.The reservoir intercept upstream runoff and decreased downstream runoff in the flood season,and the mean monthly reach runoff of Shilong decreased by 5.46%.In addition,the stored water could contribute to the streamflow in the dry season,and the mean monthly reach runoff of Shilong increased by 17.12%.When there was heavy flood upstream basin,reservoir could intercept the flood,and played a very important role in decreasing flood peak,which decreased annual mean maximum 1-day and 5-day streamflow by 13.18%and 14.2%in the Shilong gauge.In addition,in extreme low water period,reservoir could provide water to the downstream,and increased the downstream runoff,which increased annual mean maximum 1-day and 5-day stream flow by 26.26%and 125.6%.