Spatiotemporal evolution and future trend analysis of extreme precipitation events in Tuhai-Majia River Basin

Abstract

[Objective] To investigate the historical and future spatiotemporal variation characteristics of extreme precipitation events in the Tuhai-Majia River Basin, aiming to provide theoretical references for preventing potential future climate disasters. [Methods] Based on daily precipitation data from 26 national meteorological stations in the Tuhai-Majia River Basin over a 55-year period from 1967 to 2021, eight extreme precipitation indices were calculated using the RClimDex1.1 model. The Mann-Kendall(M-K) test, ANUSPLIN spatial interpolation, and wavelet transform were applied to analyze the changes in extreme precipitation indices. The NEX-GDDP-CMIP6 dataset was used to predict future climate change trends in the river basin. [Results] The result showed that:(1) from 1967 to 2021, all indices in the Tuhai-Majia River Basin showed increasing trends, except for consecutive dry days(CDD) and consecutive wet days(CWD), which showed decreasing trends. Significant abrupt changes were observed in maximum 1-day precipitation(Rx1day), very extreme precipitation(R99P), CWD, and CDD during the study period. Other indices showed no significant abrupt changes. All extreme precipitation indices exhibited notable periodic variations during the study period, with major cycles generally ranging from 2 to 4.8 years.(2) The extreme precipitation indices in the study area showed significant spatial variation. Some indices were strongly correlated with topographic factors. Total annual precipitation(PRCPTOT), total extreme precipitation(R95P), and R99P showed higher values in the southern part of the river basin, while Rx1day and maximum 5-day precipitation(Rx5day) had higher values concentrated in the northern part of the river basin.(3) Under different emission scenarios(SSP1-2.6, SSP2-4.5, SSP5-8.5) from 2015 to 2100, extreme precipitation events in the river basin were projected to generally show an increasing trend.(4) The cross-wavelet transform between extreme precipitation indices and climate indices showed different power levels. Among them, the cross-wavelet power between extreme precipitation indices and sunspot number(SN) was the strongest, showing high oscillation coherence and mostly negative correlation. [Conclusion] Overall, the variations in precipitation indices indicate that the region is becoming increasingly humid. There are significant north-south differences in extreme precipitation in the Tuhai-Majia River Basin. Future efforts should focus on optimizing differentiated disaster prevention systems in the northern and southern parts of the river basin and enhancing the monitoring, early warning, and response capabilities for extreme precipitation events to reduce disaster risks within the river basin.

Keywords

extreme precipitation index / spatiotemporal variation / Tuhai-Majia River Basin / NEX-GDDP-CMIP6 / ANUSPLIN interpolation / climate change / ENSO / influencing factors