鄱阳湖流域气象干旱向水文干旱传递的时间特征研究

Study on the Temporal Characteristics of Meteorological Drought to Hydrological Drought Propagation in the Poyang Lake Basin

认识气象干旱向水文干旱动态传播过程,对制定水文干旱预警具有重要意义。针对水文干旱传播的物理过程复杂和时空传播方面的认识不足,采用周尺度标准化降水指数、标准化降水蒸散指数和标准化径流指数,结合游程理论和贝叶斯网络分析干旱指数的特征和时间变化,探索不同等级干旱事件特征,揭示气象干旱向水文干旱传播的时间规律。结果表明:(1)鄱阳湖流域水文干旱对气象干旱的响应一般在11~15周以内,且气象干旱与水文干旱的相关性在夏秋季高于春冬季。(2)气象干旱之后发生水文干旱所占比例高达80%以上;某一等级的气象干旱发生条件下,最大可能会紧接着发生与气象干旱同等级的水文干旱事件,其次是轻于该气象干旱一个等级的水文干旱事件。(3)气象干旱发展至越高等级的水文干旱,其时间间隔越长;很难发生轻等级气象干旱演变成严重水文干旱;春冬两季干旱传播时间间隔长于夏秋两季。

Understanding the dynamic propagation process from meteorological to hydrological drought is essential for development of hydrological drought forecasting.Due to the complexity of physical processes involved in drought propagation,the spatiotemporal aspects of this phenomenon are not fully comprehended.In this study,weekly-scale Standardized Precipitation Index(SPI),Stan⁃dardized Precipitation Evapotranspiration Index(SPEI),and Streamflow Drought Index(SSI)are employed,along with run theory and Bayesian network analysis,to explore the characteristics and temporal variations of different drought events.The objective is to unveil the temporal patterns of meteorological drought transitioning into hydrological drought.The results reveal the following:(1)The response of hydrological drought to meteorological drought in the Poyang Lake Basin typically occurs within 11 to 15 weeks,with higher correlations between meteorological and hydrological droughts during summer and autumn than in spring and winter.(2)Following a meteorological drought event,hydrological drought occurs in over 80%of cases.Under certain levels of me⁃teorological drought,the most probable event is a hydrological drought of the same level,followed by a hydrological drought one level lower than the meteorological drought.(3)The higher the level of meteorological drought that evolves into hydrological drought,the longer the time interval.Moderate meteorological droughts are challenging to evolve into severe hydrological droughts.The time interval for drought propagation is longer in spring and winter compared to summer and autumn.