Characteristics and Lag Time of Meteorological Drought Propagation to Hydrological Drought in the Haihe River Basin

Understanding the propagation dynamics from meteorological to hydrological droughts, particularly in regions heavily influenced by human activities, is essential for the effective monitoring and prevention of hydrological drought risks. This study focuses on the Haihe River Basin, investigating the evolution of meteorological and hydrological droughts using the Standardized Precipitation and Evapotranspiration Index and the Standardized Runoff Index, supplemented by run theory analysis. Using correlation analysis, we examine the propagation lag times between meteorological and hydrological droughts. Our results indicate a worsening drought trend in the Haihe River Basin over the past six decades. Notably, a turning point occurred in 1991, where meteorological droughts began to abate, while hydrological droughts intensified, highlighting a divergence in trends between meteorological and hydrological droughts. We identify four distinct pathways for the transition from meteorological to hydrological droughts in the region. This study identifies a hydrological drought lag time of 3 months. The occurrence of droughts in the Haihe River Basin is becoming increasingly frequent. Furthermore, our findings reveal that the severity of hydrological droughts is increasingly exceeding that of meteorological droughts, and the influence of meteorological conditions on hydrological droughts is diminishing, while human activities may become a more significant contributing factor. The findings from this research enhance our comprehension of how drought propagation trends and characteristics are shaped by significant human influences, thereby offering pivotal insights for managing water resources at the basin level.