Simulation And Prediction Of The Mountainous Runoff In The Shule River Basin Under Climate Change

The ecological environment in the northwest is fragile,and the mountainous runoff in the inland river basin is extremely vulnerable to climate change and human activities.As one of the three major inland river basins in the Hexi Corridor,the Shule River Basin is located deep in the hinterland of the northwestern inland.Affected by climate change,the runoff from the Shule River Basin has undergone major changes.In-depth analysis of the changes in meteorological and hydrological elements of the Shule River Basin and prediction of the change trend of runoff in the Shule River Mountainous Area in the future are of great significance to the socioeconomic development of the region.This paper uses the Shule River Basin as the research area,using trend analysis and mutation analysis methods to explore the change characteristics of precipitation,temperature,runoff and other factors in the Shule River Basin from 1981 to 2015.On this basis,the distributed hydrological model PRMS was selected,aiming at the special hydrological process of the Shule River Basin,the glacier module was embedded in the model,and the changes of the runoff for the Shule River were simulated,and based on the sixth international coupling model comparison Program(CMIP6)output data of six global climate models,combined with the Multivariate Bias Correction,analyzed the future change trends of temperature and precipitation in the Shule River Basin under four climate change scenarios,and realized the Prediction of runoff from the mountains in the Shule River Basin.The main research results of this paper are as follows:(1)The precipitation at the three meteorological stations of Dunhuang,Tuole,and Yumen showed an insignificant increase trend on an annual scale,while the temperature of the three meteorological stations showed a significant increase trend,especially at the end of the 20 th century and the beginning of the 21 st century.The change characteristics of the stations are similar,showing obvious trends;the runoff at the Changmabao station has shown a significant increase trend,and the changes in flow are greatly affected by precipitation and temperature,especially in June-August.The seasonal changes are obvious.(2)Combining the conclusions of the mutation analysis,divide the historical period into the calibration period(1981-2000)and the verification period(2001-2015).Based on the PRMS model,select NSE,RSR,PBIAS,R~2,RE,etc.Indicators to evaluate the simulation results.Among them,the values during the calibration period are 0.65,0.59,3.90,0.80,6.90,and the values during the verification period are 0.71,0.54,-12.80,0.77,-12.80.According to the evaluation criteria by Morris,it shows that the simulation effect of the model is better.It can be applied to the simulation of the flow in the mountainous area of Shule River.(3)Use the corrected CMIP6 climate model data of precipitation,maximum temperature,minimum temperature,and average temperature for trend analysis.During the simulation period(1981-2014),the monthly scale analysis of various meteorological elements is performed.The results show that the corrected model data can better fit the meteorological changes in the mountainous area of the Shule River,and the evaluation accuracy is high.The runoff under the climate change scenarios will have different trends in the future(2015-2100).In 2015-2040,except for the most obvious change in the maximum temperature under the SSP5-8.5,other meteorological elements changes greatly under the SSP1-2.6.The most obvious increase was observed in 2041-2070;precipitation and average temperature increased significantly under the SSP2-4.5 in 2041-2070,while the maximum and minimum temperature changed significantly under SSP1-2.6;in 2071-2100,the change trends of the four meteorological elements are the most obvious under the SSP5-8.5.Using model data to predict the future climate,it can be seen that in the second half of the 21 st century,precipitation in the Shule River Basin has gradually increased,and the temperature has also risen significantly.The climate gradually turns to warm and humid,and the temperature difference in the future period will be further reduced.(4)Under different climate scenarios,the future flow changes will be different,but on the whole,as time goes by,the runoff from the Shule River shows an increasing trend.In 2015-2040,runoff under the SSP1-2.6 has the largest increase.In 2041-2040,the increase of the runoff under the SSP3-7.0 is the largest.In 2041-2100,the increase in runoff under the SSP5-8.5 is the largest.From a monthly scale analysis,runoff has obvious seasonal changes,showing an "increasing-decreasing" trend.