Variation and propagation characteristics of meteorological and hydrological droughts in Longitudinal Range-Gorge Region

Abstract

[Objective] Global climate change and human activities have profoundly altered drought dynamics, particularly in ecologically sensitive regions. This study analyzes the propagation characteristics and mechanisms of meteorological drought(MD) and hydrological drought(HD) on both sides of the southern Gaoligong Mountains within the Longitudinal Range-Gorge Region( LRGR), aiming to provide scientific foundation for effective water resource management and disaster prevention. [Methods] Based on the significant hydrometeorological differentiation between both sides of the southern Gaoligong Mountains,and using monthly precipitation and runoff data between 1981 and 2020 from representative river basins, the intensity and frequency of MD and HD were evaluated using the standardized precipitation index(SPI) and standardized runoff index(SRI).Variation trends of drought indices were analyzed through Mann-Kendall trend tests. Run theory was employed to evaluate the propagation time lag from MD to HD, followed by a Bayesian ordinal probit regression model to quantify the relationship between cumulative precipitation deficits(SPIm) and HD severity. [Results] The result showed that over the past four decades, MD intensity in the LRGR had increased significantly. The frequency of MD events( approximately 2. 2 to 2. 5 events/year) was notably higher than that of HD events(approximately 1. 1 to 1. 5 events/year). HD events demonstrated longer duration(2. 18 to 3. 04 months) and greater severity(1. 18 to 1. 76). The propagation from MD to HD was relatively rapid, with an average time lag of 0. 5 to 0. 7 months, while the recovery process showed longer lags(1. 2 to 2. 2 months). The Bayesian analysis revealed a negative correlation between SPIm and HD severity, with increased uncertainty in this relationship under extreme MD conditions. [Conclusion] High-intensity HD may constrain agricultural and socio-economic activities in the region. The rapid response to MD and the prolonged HD recovery highlight emerging challenges for sustainable water resource utilization in this area. These findings enhance the understanding of drought propagation processes in mountainous ecosystems and provide scientific support for adapting water resource management strategies to climate change.

Keywords

climatic change / meteorological drought / hydrological drought / drought propagation / Longitudinal Range-Gorge Region / influencing factors