Study on the spatiotemporal distribution characteristics of extreme temperature indices in Dadu River Basin
[Objective]Under global climate change,the frequency and intensity of extreme climate events are increasing,which have a significant impact on the basin environment.The Dadu River Basin is not only an important part of the ecological barrier in the upper reaches of the Yangtze River and the Sichuan-Yunnan ecological barrier,but also a key distribution area of the arid and semi-arid valleys in the Yangtze River Basin,and there are many protected fish species in the basin,which is sensitive to climate change.The spatiotemporal distribution characteristics of extreme temperature index in Dadu River Basin were explored.[Methods]The Dadu River Basin was taken as the research area.Based on the daily meteorological data of the basin from 1964 to 2018,the extreme temperature index of the Dadu River Basin was analyzed by linear fitting,Sen's slope estimation and Mann-Kendall nonparametric test.The spatial distribution of extreme temperature index was analyzed by using the co-Kriging method.[Results]The extreme temperature events in the Dadu River Basin have obvious interannual changes.Among the 16 extreme tem-perature indices,11 indices showed an upward trend and 5 indices showed a downward trend.In addition to the extreme tempera-ture,the fastest rising rate is SU25,the rising rate is 2.0d/10a;the fastest decline rate is ED0,and the decline rate is 1.6 d/10 a.Except for the change trend of CSDI and WSDI in the basin is 0,the change rate of the other extreme temperature indexes had obvious differences in the spatial distribution,and the altitude is the main influencing factor leading to the spatial distribution characteristics of the extreme temperature indexes in the Dadu River Basin.[Conclusion]On the time scale,the warm index in the extreme temperature index of the Dadu River Basin showed an upward trend;the cold index(except TNn and TNx)showed a downward trend.In other indexes,GSL rises faster.This indicates that the basin has shown a warming trend in the past 55 years,with shorter winter and longer summer,and the temperature duration suitable for vegetation growth has increased.The mutation test showed that the mutations of each extreme temperature index were significant except for TN 10,and the mutation years were concentrated around 2000.On the spatial scale,the upward rate of ID0 and FD0 in the cold index is higher than that in the middle and lower reaches,the upward rate of TR20 and SU25 in the warm index is higher than that in the upper reaches,and the upward rate of GSL in the upper reaches is significantly higher than that in the middle and lower reaches.The whole basin is warming and the middle and lower reaches are more prone to extreme high temperature events.This study can provide a scientific basis for early warning of extreme climate disasters and water ecological protection in the Dadu River Basin.
extreme temperaturespatial and temporal distributionDadu River Basinclimate changeYangtze River BasinMann-Kendall testKriging methodwater ecological protection
万方数据
维普
