Spatiotemporal distribution characteristics and driving factors of drought in Minjiang River Basin from 1962 to 2021

Abstract

[Objective] Under the background of global warming, drought frequency has shown an increasing trend in southern China. However, research on drought in the humid river basins of the southeastern coastal area remains insufficient. Investigating the spatiotemporal evolution characteristics and driving factors of drought in the Minjiang River Basin is of great significance for drought risk assessment and the formulation of scientific water resource management strategies. [Methods] Based on daily precipitation and temperature data from 26 meteorological stations in the Minjiang River Basin, the standardized precipitation evapotranspiration index(SPEI) was calculated as the drought indicator. [Methods] including the Mann-Kendall trend test, cross wavelet analysis, and wavelet coherence analysis were used to analyze the spatiotemporal variation characteristics of drought across different time scales in the river basin. Additionally, the effects of climate conditions and large-scale circulation factors on drought characteristics were explored. [Results] The result showed that from 1962 to 2021, the annual-scale SPEI in the river basin increased at a rate of 0. 030/10 a. The change rates of SPEI in spring, summer, autumn, and winter were-0. 013/10 a, 0. 051/10 a,-0. 016/10 a, and-0. 003/10 a, respectively. Spatially, 19 stations(73. 08% of the total) exhibited a drying trend at the annual scale. The proportions of stations showing drying trends in spring, summer, autumn, and winter were 65. 38%, 26. 92%, 76. 92%, and 69. 23%, respectively. [Conclusion] Over the past 60 years, the Minjiang River Basin has exhibited an insignificant wetting trend, but with seasonal differences. Spring, autumn, and winter exhibit a wetting trend, while a wetting trend is observed in summer. Significant wetting trends are observed in the northern and southeastern parts of the river basin, while drying tendencies are observed in the central and southern regions. The drought frequency is higher in the northeastern and southwestern parts of the river basin, with the eastern region prone to drought in spring and autumn, and the southern region prone to drought in winter. Precipitation is a key factor influencing drought at different time scales in the Minjiang River Basin, and temperature exhibits significantly negative correlations with drought in spring, autumn, and winter. Drought in the Minjiang River Basin is closely related to the El Niño-Southern Oscillation(ENSO) and the Arctic Oscillation(AO). The SPEI shows a resonance period of approximately 0~5 months with ENSO and 3~6 months with AO.

Keywords

drought / SPEI / spatiotemporal distribution / large-scale circulation factors / Minjiang River Basin / influencing factors / cross wavelet analysis / wavelet coherence analysis