The Simulation And Prediction Of River Basin Runoff Considering Meteorological Factors And Land Use Types

Affected by the dual factors of global climate change and human activities,the problem of water resources is becoming more and more serious,which has brought great potential harm to the development of social economy and the construction of ecological civilization.Under the influence of extreme climate and underlying surface changes,serious soil and water loss,frequent flood disasters and increasingly exhausted water resources in the river basin have attracted great attention.Therefore,on the basis of analyzing the variation characteristics of runoff,it is of great significance to analyze the influence of meteorological factors and land use factors on runoff,and to simulate and predict the change of runoff in the future,for relieving the shortage of water resources,formulating soil and water conservation measures,and preventing drought and flood disasters in the basin.Taking the Dapoling Basin of the upper reaches of Huaihe River as the study area,this paper analyzed the variation characteristics of annual runoff by statistical method and explored its causes.The contribution rates of climate change and human activities to runoff change were quantified by elastic coefficient method,redundancy analysis method and hydrological model method.The SWAT model was coupled with the SDSM model and the CA-Markov model,respectively,to simulate and predict the meteorological,hydrological and land use changes in the basin in the next 20 years.The main results of the study are as follows:(1)M-K test,Pettitt test,wavelet analysis,R/S analysis and other methods were used to analyze the variation characteristics of runoff in Dapoling Basin.The results show that the annual runoff has a slow decreasing trend and a sudden change occurred around 1992.The main period of annual runoff change is 12 years,and the runoff will have a slight increasing trend in recent 12 years.(2)The annual rainfall in the basin showed a decreasing trend,but there was no abrupt change.Rainfall was not the only factor causing abrupt change in runoff,and the influence of human activities on runoff changes could not be ignored.In the past30 years,the area of cultivated land has been continuously decreasing,the area of forest land has been continuously increasing,and the surface vegetation coverage has been continuously increasing.The change of land use has made the decreasing trend of runoff more obvious.The increase of water retaining capacity of water conservancy projects in the basin also leads to the decrease of runoff.(3)The results based on the elastic coefficient method,redundancy analysis method and hydrological model method are consistent.The contribution ratio between climate change and human activities during 1991-1999 is about 1:1,and the contribution ratio between climate change and human activities during 2000-2013 is about 7:3.Redundancy analysis method can better obtain the contribution ratio of meteorological factors and land use change,but can not take into account the impact of other human activities.(4)The SWAT model was constructed for the Dapoling Basin.The E_NS and R² of the model calibration period were 0.90 and 0.91,respectively,and the E_NS and R² of the verification period were 0.86 and 0.88,respectively,indicating that the SWAT model has good applicability in the Dapoling Basin.Through different scenarios and model simulation,it is found that the soil water and groundwater in Dapaling Basin are affected by the land use type and soil texture of the basin,among which the forest land has a strong water-interception ability,and the cultivated land can better maintain the soil water,but the groundwater recharge ability is insufficient.(5)The SDSM model is used to simulate the future climate scenarios of the basin.The results show that the total precipitation in the basin will increase and the temperature will increase significantly under the Can ESM2 RCP4.5 scenario.CA-Markov model is used to simulate the future land use of the basin.The results show that the area of forest land will increase and the area of cultivated land will decrease in the future.Through the simulation of SWAT model,it is concluded that the runoff will increase in the future,especially in flood season.