| Taking Dawen River Basin as the research object,this paper first establishes the HEC-HMS model of Dawen River Basin,simulates the inner diameter flow of the basin in different historical stages,and evaluates and analyzes the simulation results of the model to determine its accuracy.Then the SDSM model of the basin is created.Through the further analysis of the measured precipitation data and NCEP reanalysis data,the prediction factors are determined and the model is calibrated.At the same time,the simulation effect of the model is analyzed by using scientific methods.Based on the SDSM model,rcp2 under canesm2 model can be used 6、RCP4.5 and rcp8.5 three schemes are used to simulate the future precipitation.Finally,the results of future rainfall scenarios are introduced into HEC-HMS model to analyze the changes of future runoff.The conclusions are as follows:(1)Using the linear tendency estimation method and m-k catastrophe test,it is found that the precipitation and runoff in the base period show an increasing trend.However,compared with the change of precipitation,the change range of runoff is relatively small.(2)The efficiency coefficient(DC)of NASH-Suttcliffe model,QR of qualified rate and n_t were used to evaluate the simulation accuracy of HEC-HMS mode.In the 22-year historical period from 1994 to 2015,16 years were qualified and 6 years were unqualified.The QR was0.72,which reached grade B evaluation standard on the whole.The results show that the HEC-HMS model can be used to further analyze the runoff under the future climate change in the Dawen River Basin.(3)The simulation accuracy of HEC-HMS model is comprehensively evaluated through a series of methods,namely,the efficiency coefficient(DC),qualified rate QR value and value of Nash suttclife model.In the 22-year historical period from 1994 to 2015,16 year forecasts are qualified and 6-year forecasts are unqualified.The overall QR value is 0.72 and the overall evaluation grade can reach grade B.the research results show that it is feasible to use the established HEC-HMS model to study and analyze the runoff change under future climate change in Dawen River basin.(4)Verify the SDSM model and simulate rcp2 in can esm2 mode through the model 6、RCP4.5 and rcp8.5.According to the precipitation under the three scenarios,the rcp2 of Dawen River from 2026 to 2100 is obtained 6、RCP4.5 and rcp8.5 daily precipitation data under three modes.Through further analysis and Research on the obtained data:the average annual precipitation is rcp2.6、RCP4.5 and rcp8.5.It shows an increasing trend under the three scenarios;During the simulation period from 2026 to 2100,the simulated value has an obvious upward trend compared with the measured value,but the water volume decreases in each scenario mode;Under different scenarios,the variation range of precipitation is different,and the largest decline rate is rcp4.5.In the scenario mode,rcp8 has the largest increase rate 5.Profile;The precipitation peak of each period is different under different scenarios,but in the whole simulation period,the precipitation peak under the three scenarios is in July.(5)Input the future precipitation data simulated by SDSM model into the time series module of HEC-HMS model,so as to obtain the daily flow data of hydrological stations in the study area from 2026 to 2100 under each scenario mode.Further research and analysis of the obtained data shows that the annual average flow has an obvious upward trend under each scenario mode;The flow in each period is at rcp2.6、RCP4.5.Under the scenario mode,it basically shows an upward trend compared with the measured period,rcp8.5.Under the scenario mode,it basically shows a downward trend compared with the measured period;The flow change ranges under the three scenarios are different,among which rcp2.6.The rise rate is the highest in the scenario mode,rcp8.5.The decline rate is the highest in the scenario mode;With the worsening of climate scenario,the flow shows an increasing trend;The flow has the characteristic that the peak time moves back. |
