| The runoff of seasonal rivers(flood ditch)in the southeastern margin of the Kumtag desert mainly comes from the melting water of snow and ice and rainfall in Altun Mountains.At present,there are few studies on hydrological process based on long time series hydrological data.To clarify the runoff characteristics and hydrological processes of seasonal rivers in arid areas.In this study,the seasonal river Cuimutugou in the southeastern margin of the Kumtag desert was taken as an example,the runoff monitoring,soil water leakage monitoring and meteorological monitoring in a long period of time were carried out in the Cuimutugou,and the soil,vegetation and land use status were collected.And constructed SWAT model of Cuimutugou,discusses the applicability of SWAT model in Cuimutugou,and analyzed the error.The main research results are as follows:(1)The runoff of Cuimutugou is small,during the monitoring period from September2016 to October 2018(excluding the data of December,January and February),the average water level,flow rate,the flow and the corresponding distribution range were 19.25(9.1～306)cm,1.29(0.61～3.89)m/s,0.43(0.1～156.53)m~3/s,The total runoff reached 2070.09 10~4m~3.In the case of no obvious rainfall,the surface runoff of the Cuimutugou comes from the exposed spring water,the water level is mainly distributed between 9.1-39.1 cm,and the flow is concentrated between 0.1～0.41 m~3/s.The rate at which the spring water emerges will increase as spring temperatures rise which can cause floods.(2)The floods of the Cuimutugou can be divided into snowmelt flood,spring flood and summer flood.Snowmelt flood is related to temperature,while spring flood and summer flood are related to rainfall.Rainfall is an important driving force for the formation of the flood,the change of runoff is sensitive to the response of rainfall and rainfall intensity.When the rainfall is less than 5mm,the surface runoff has no obvious change.When the rainfall is more than 10mm and continuous rainfall occurs,the surface runoff will have obvious changes in water level and velocity,the maximum runoff will not exceed 0.8 m~3/s.When the rainfall is more than20mm and relatively concentrated and continuous,a large flood process will be generated.During the monitoring period,the maximum peak flow is up to 156.53 m~3/s.(3)In this study,SWAT model was used to simulated runoff of the Cuimutugou,according to the DEM map,land use map and soil type map,it is divided into 33 sub-basins and 59 hydrological response unit.Combined with the measured runoff data of the Cuimutugou,the daily and monthly runoff were simulated,calibrated and verified.During the model calibration period,the Nash efficiency coefficient,relative deviation and correlation coefficient of daily runoff simulation were 0.63,13.46 and 0.65.and monthly runoff simulation were 0.63,15.09 and 0.62.During the model validation period,the Nash efficiency coefficient,relative deviation and correlation coefficient of daily runoff simulation were 0.58,14.81 and 0.57,and the monthly runoff simulation was 0.61,14.28and 0.61.In general,the simulation effect of SWAT model in the Cuimutugou meets the basic requirements of the model,but there is still some error.(4)There were 4 times obvious continuous leakage in the 160 cm soil layer of the seasonal reach of the Cuimutugou during the monitoring period from September 2016 to July 2017,the total amount of leakage was 2165.8 mm,and the maximum leakage strength was 21.4mm/2h.The soil water leakage rate increased exponentially with the increase of soil water content,but the initial soil water content of continuous leakage was not consistent every time.In each infiltration process,there is a good linear correlation between the depth of the wet front to the soil layer and the infiltration time,but this correlation is obviously different in spring and summer,and the water infiltration is slower in spring. |
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