| As global climate change intensifies,future runoff in the Huaihe River Basin will undergo drastic changes,and the task will be to figure out how to deal with such changes.To better analyze the shifting features of runoff under future climate change,it is essential to create an accurate runoff simulation model that allows for the prompt avoidance and settlement of potentially unfavorable situations.This paper uses the watershed above the Xiaoliu Lane hydrological station as the study area.Based on historical meteorological and hydrological data from 1991 to 2019,spatial and temporal trends in climate and runoff over the historical period were analysed using the Mann-Kendall trend test.The Delta method,Quantile Mapping(QM)and Statistical Down-Scaling Model(SDSM)were then compared for the downscaling of future climate data(GCMs)from the Coupled Model Intercomparison Project phase 6(CMIP6).The Delta method,which has the best downscaling effect,was chosen to downscale the GCMs and then to analyse the spatial and temporal trends in climate in future period,which were then fed into a hydrological model applicable to the study area to analyse the changes in runoff in future period.The following conclusions were obtained:(1)From 1991 to 2019,there was no noteworthy change in precipitation in the Huaihe River basin,with daily maximum and minimum temperatures increasing significantly by0.24°C/10 a and 0.45°C/10 a respectively,both showing a spatial distribution of lower values at higher latitudes;(2)The runoff of the Huaihe River Basin changed drastically from 1991 to2019,and the transition from wet years to dry years was relatively frequent,among which the runoff at Changtaiguan Station fluctuated the most.The results of the mutation analysis showed that no significant mutations in runoff occurred at any of the nine hydrological stations;(3)The three downscaling methods,Delta,QM and SDSM,all have a good ability to simulate the temperature variable(correlation coefficient can be >0.99),while the ability to simulate precipitation varies,with Delta being the best for precipitation,with a correlation coefficient of0.95;(4)In the four future scenarios(SSP1-2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5),the Huaihe River Basin is anticipated to see increases in precipitation,daily maximum temperature,and daily minimum temperature.Predictions show that temperature will rise faster than precipitation.In terms of spatial distribution,precipitation shows a trend of fast growth in the north and slow growth in the south,while the daily maximum and minimum temperatures show little spatial fluctuation.In terms of temporal variation,precipitation is expected to increase by approximately 3.81% during 2024-2050,7.64% during 2051-2075,and a maximum of 11.41%during 2076-2100.Daily maximum and minimum temperatures are expected to increase by1.66℃ and 1.69℃,respectively,during 2024-2050,2.71℃ and 2.68℃ during 2051-2075,and 3.68℃ and 3.63℃ during 2076-2100.At the seasonal scale,the proportion of precipitation in spring and summer is expected to increase under all four scenarios,while daily maximum and daily minimum temperatures increase at the highest rate in winter and at the lowest rate in summer.;(5)The runoff in the Huaihe River Basin is higher than the historical period under all four future scenarios.The runoff under the SSP1-2.6 scenario peaks from 2024 to 2050 and shows a decreasing and then increasing trend from 2051 to 2075 and 2076 to 2100;the runoff under the SSP2-4.5 and SSP3-7.0 scenarios increases significantly from 2024 to 2050 and then decreases slightly;the runoff under the SSP5-8.5 scenario 2024 to 2100 shows a continuous increasing trend;Compared with the historical period,the proportion of runoff in the Huaihe River Basin increased in the winter half of the year,and decreased in the summer half of the year. |
