Simulation Study Of Spring Snowmelt Runoff In Emmur River Basin Based On SWAT Model

Glacial snow is an important freshwater resource on earth,and in some regions,snow melt is the main source of recharge for river runoff in spring,which has a great impact on local farming and production life.The northeast region is one of the three most stable snow areas in China,and also an important food and forestry production base in China.It is important to study the influencing factors of snowmelt runoff and construct snowmelt runoff models for spring snowmelt runoff forecasting in the watershed.In this paper,we analyze the trend changes,sudden change points,future trends and correlations of runoff and meteorological factors in the basin,determine the time of snowmelt runoff in the basin by combining the baseflow segmentation method and box plot,study the influence of meteorological factors on the runoff volume during the snowmelt runoff period,and finally build the snowmelt runoff model in the basin based on ArcGis10.2 platform.The main results are as follows.(1)Based on the measured hydro-meteorological data in the basin,the annual and seasonal trends and correlations of hydrological and meteorological factors are analyzed by the basic analysis method,the annual runoff and annual precipitation in the basin are decreasing,the annual average temperature is increasing,and the trends of runoff and meteorological factors in the future time period have inverse continuity;the trends of meteorological factors in the year are in accordance with the seasonal changes,and the precipitation is decreasing in spring,summer and autumn.Except for winter,the correlation between runoff and precipitation and mean temperature is high,with runoff being positively proportional to precipitation and inversely proportional to temperature,and changes in precipitation and temperature have a greater impact on spring runoff..(2)Based on the smoothed minimum method and ECK recursive digital filter method to calculate the baseflow values in the basin,draw baseflow process lines in the basin,analyze the baseflow process lines in the study period and introduce box plots to statistically analyze the snowmelt runoff period in each year,and finally determine the snowmelt runoff period in the basin from April 17 to May 23;the meteorological factors with the highest correlation with the snowmelt period are relative humidity,average surface temperature,The meteorological factors with the highest correlation with the snowmelt period are relative humidity,average surface temperature,evaporation,sunshine hours,snowmelt runoff is negatively correlated with evaporation,and the rest of meteorological factors are positively correlated.(3)The processed spatial data as well as meteorological data were imported into the SWAT model to construct the SWAT model within the watershed,and finally the study area was divided into 15 sub-basins with 105 hydrological response units.1959-1960 was selected as the preheat period,1961-1969 as the rate period,and 1971-1975 as the validation period to simulate the snowmelt runoff in the watershed,and the snowmelt runoff was simulated using the The SWAT-CUP application was used to perform sensitivity analysis and rate determination of the parameters to finalize nine parameters,and iterations were repeated until the evaluation index did not change.The Nash coefficient(Ens)and correlation coefficient(R2)of the rate period and rate period were greater than 0.6,and the relative error(Re)was less than or equal to 25%,and the evaluation indexes of the rate period and validation period were within the range,that is,the accuracy of the constructed model met the requirements.