Analysis Of The Influence Of Frozen Soil On Snowmelt Runoff In Xilin River Basin And Snowmelt Runoff Simulation

Water resources are an important resource on which life depends and are closely related to social and economic development.my country's water resources are unevenly distributed between the north and the south.In recent years,under the influence of climate change,the frequency of extreme hydrological events such as heavy rainfall and continuous drought has shown an increasing trend.The Xilin River is one of the largest inland rivers in the grasslands of Inner Mongolia.The runoff of the river is an important factor for maintaining the water supply of the basin and the sound development of the ecological environment,and it is a decisive factor for the sustainable social and economic development of the basin.The surface runoff of Xilin River has obvious double-peak characteristics,mainly from spring snowmelt water and precipitation in summer and autumn.Due to the influence of seasonal frozen soil layer,the formation process of spring snowmelt runoff is different from other periods.Based on the daily data of Xilinhot Meteorological Station from 1960 to 2020 and the daily runoff data of Xilin River Hydrological Station from 1963 to 2020,the linear regression method,MK non-parametric test method,and R/S method are used to analyze the decline of the Xilin River Basin at different time scales.The changing trend of water,temperature and runoff.The results show that the temperature in the Xilin River Basin is on the rise.The temperature characteristics in the growth period,the initial freezing period,and the freezing period are basically the same as the annual characteristics.The temperature rises significantly during the freezing and thawing period.During the period,the precipitation showed a decreasing trend,the initial freezing period and the freezing period showed an upward trend,and the winter precipitation showed a significant upward trend;the snowmelt runoff of the Xilin River was affected by the temperature and precipitation and showed a trend of occurrence in advance.Snowmelt runoff is a hot issue in the study of hydrology and water resources in arid regions,and it is very important for the risk assessment of spring snowmelt floods in arid regions and water resources management in river basins.In this thesis,the SWAT model is selected to simulate the spring snowmelt runoff in the Xilin River Basin.Due to the existence of the frozen soil layer in the basin,a temporary impervious layer is formed,which weakens the regulation and storage effect of the snowmelt runoff on the surface of the soil.In addition,the river channel is relatively shallow.The "freezing of the bottom" of the river lasted for about 100 days.Therefore,this thesis analyzes the impact of frozen soil on snowmelt runoff in detail.When establishing the model,the control effect of soil temperature and soil moisture on the formation,development and decline of frozen soil is fully considered,and the parameters are calibrated to make the simulation The result is in line with reality and closer to the measured value.This thesis uses the SWAT model to simulate the snowmelt runoff process with 6different models,the simulated satisfaction is good.From the change trend of runoff,it can be seen that the future temperature rise will play a negative role in the change of runoff,that is,the temperature rise will increase soil input.Seepage volume and evapotranspiration,the occurrence time of snowmelt runoff and the peak arrival time are earlier,and the total runoff and peak flow are reduced;the increase in precipitation has a positive contribution to the change of runoff,and the increase in precipitation of different degrees will make the total runoff and peak flow increase.From the perspective of the degree of action,precipitation is the main factor exerting influence,but when the temperature rises more than 1?,the runoff will be significantly reduced,so temperature changes are also a factor that cannot be ignored in affecting the snowmelt runoff.