Research On The Response Of Yalong River Runoff To Climate And Land Use Change Based On SWAT Model

With the rapid development of the world economy,global warming and the pace of urbanization are gradually accelerating,which brings with it enormous challenges to global water resources.The total amount and distribution of global water resources have been affected to varying degrees,especially for residential water,water pollution,and agricultural irrigation.This paper studies the changes of hydrological situation in the Yalong River Basin under the climate change conditions,obtains the soil,elevation,land use and runoff data of the Yalong River Basin through investigation,constructs the SWAT model of the Yalong River Basin,and explores through simulation calculation analysis Response mechanism of runoff to climate and land use change in the Yalong River Basin.The main research work and results of this article are as follows:(1)Based on the 1987-2018 meteorological data,a SWAT model was built for the Yalong River Basin,and 26 parameters that had a greater impact on the runoff results of the river basin were selected.SWAT-CUP software was used for sensitivity analysis,and the top 13 parameters were selected.The model is divided into three periods: model warm-up period,rate period and verification period.The applicability of the model in the Yalong river basin is analyzed.The calculation and analysis results show that the established SWAT model has high accuracy and can be applied to the Yalong river.Watershed runoff simulation.(2)For the study on the mechanism of runoff response to climate change in the river basin,the hypothetical climate scenario method was adopted to set the precipitation change rate to ±20%,±10%,0%,and the temperature change to ±2?,±1?,At 0°C,24 climate scenarios were constructed for runoff simulation.The simulation results show that: the impact of precipitation changes on the Yalong River runoff is greater than that of temperature;the amount of precipitation increases and the runoff increases;the temperature increases and the runoff decreases;when the temperature increases And when the precipitation is reduced,the decrease of runoff is the most significant.(3)In order to explore the mechanism of river basin runoff response to land use changes,three extreme land use scenarios were designed using extreme land use methods and land use spatial allocation methods,and combined with social development trends,urbanization,cultivated land expansion,and soil and water conservation were established.Three scenario modes;calculation and analysis results show that: forest land and grassland in the land type will reduce the runoff of the watershed,and cultivated land will increase the runoff of the watershed;the runoff capacity in different scenarios is quite different,and the initial judgment is that cultivated land>grassland>forest land.(4)Combining climate scenarios and land use scenarios,the sensitivity of watershed runoff to climate change and land use change and the response of watershed runoff in a changing environment are analyzed;simulation results show that the impact of climate change on watershed runoff is greater than the land use belt Impacts,climate change-induced changes in watershed runoff dominate the trend of watershed runoff;the accelerated urbanization process has increased residential land use,reduced land infiltration and increased runoff;watershed management departments should formulate land management policies should Combined with climate change,focus on the balance between forest land and residential land.