Meteorological drought is the fuse of hydrological drought, and understanding the propagation mechanisms from meteorological to hydrological drought is of great significance to the monitoring and prevention of hydrological drought. Besides the linear dependence, this study thoroughly investigated the propagation from meteorological to hydrological drought by introducing the nonlinear dependence with directed information transfer index (DITI) for the first time. In this study, the standardized precipitation index and the standardized runoff index were used to represent meteorological drought and hydrological drought, respectively. A new drought response time (DRT) evaluation system was constructed based on the maximum Pearson correlation coefficient and DITI, simultaneously considering the linear and nonlinear relationships between meteorological drought and hydrological drought. Moreover, the relationships of drought characteristics (duration and severity) between these two types of drought were established by using run theory and mathematical function, and the trigger thresholds from meteorological to hydrological drought were then determined. The results indicate that: (a) the effective drought propagation rate was mainly affected by the characteristics of meteorological drought events and the sensitivity of hydrological drought to meteorological drought; (b) the DRT in the Pearl River Basin (PRB) was mainly concentrated in 2–5 months, and the drought translation rate in the PRB was relatively large; and (c) the duration of hydrological drought events was longer in the sub-regions with smaller meteorological drought trigger thresholds.

中文翻译：

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通过引入具有定向信息传递指数的非线性相关性研究从气象干旱到水文干旱的传播

气象干旱是水文干旱的导火索，了解气象干旱到水文干旱的传播机制对水文干旱的监测和防治具有重要意义。除了线性相关性外，本研究首次通过引入非线性相关性和定向信息传递指数（DITI），深入研究了从气象干旱到水文干旱的传播。本研究分别采用标准化降水指数和标准化径流指数来表示气象干旱和水文干旱。基于最大Pearson相关系数和DITI构建了新的干旱响应时间（DRT）评价体系，同时考虑气象干旱与水文干旱之间的线性和非线性关系。此外，利用运行理论和数学函数建立了这两种干旱类型之间的干旱特征（持续时间和严重程度）的关系，并确定了从气象干旱到水文干旱的触发阈值。结果表明：(a)干旱有效传播速率主要受气象干旱事件特征和水文干旱对气象干旱敏感性的影响；(b)珠江流域（PRB）DRT主要集中在2-5个月，PRB干旱转化率较大；