School of Hydrology and Water Resources, Nanjing University of Information Science and Technology, Nanjing, China.
Center for Water Resources and Environment, Sun Yat-sen University, Guangzhou, China.
Sci Total Environ. 2021 Apr 15;765:144232. doi: 10.1016/j.scitotenv.2020.144232. Epub 2020 Dec 24.
Hydrological drought usually lags behind meteorological drought. Obtaining the propagation threshold (PT) from meteorological drought to hydrological drought is important for providing early warnings of hydrological drought. Previous studies have only used single timescales to characterize PT; however, a single timescale cannot accurately describe the propagation attributes from meteorological to hydrological drought because drought has multi-timescale features. In addition, several methods can be used to obtain PT, such as run theory, correlation analysis, and non-linear response methods. However, these methods might produce different estimates of PT. Here, multi-timescale drought indices, namely the Standardized Precipitation Index (SPI) and Standardized Streamflow Index (SSI), were used to represent meteorological drought and hydrological drought. PT estimates at multiple timescales (e.g., 1-month, 3-month, and 12-month) obtained from run theory, correlation analysis, and non-linear response methods were compared, and the possible reasons for differences in the PT estimates are discussed. We conducted a case study of three sub-basins (Xinfengjiang River, Qiuxiangjiang River, and Andunshui River) with low levels of human activity in the Dongjiang River Basin, which is located in a humid region in southern China. We found that estimates of PT differed at different timescales of drought indices and with different methods at the same timescales. Longer timescales of hydrological drought corresponded to larger PT and vice versa. The major cause of this pattern was the fact that different timescales of drought indices showed different response sensitivities to drought events. The PT obtained from run theory was the shortest; thus, run theory can provide conservative warnings to aid drought prevention and mitigation. Our findings can help drought managers select effective tools to manage the early stages of hydrological drought based on meteorological forecasts and thus minimize the negative impacts of hazards posed by drought.
水文干旱通常滞后于气象干旱。从气象干旱到水文干旱获取传播阈值（PT）对于提供水文干旱预警非常重要。以前的研究仅使用单一时间尺度来表征 PT；然而，由于干旱具有多时间尺度特征，单一时间尺度无法准确描述从气象到水文干旱的传播属性。此外，有几种方法可用于获取 PT，例如运行理论、相关分析和非线性响应方法。然而，这些方法可能会产生不同的 PT 估计值。在这里，多时间尺度干旱指数，即标准化降水指数（SPI）和标准化流量指数（SSI），用于表示气象干旱和水文干旱。使用运行理论、相关分析和非线性响应方法在多个时间尺度（例如，1 个月、3 个月和 12 个月）上获得的 PT 估计值进行了比较，并讨论了 PT 估计值差异的可能原因。我们对位于中国南方湿润地区的东江流域三个低人类活动子流域（新丰江、秋香江和安敦水）进行了案例研究。我们发现，在不同的干旱指数时间尺度和相同时间尺度的不同方法下，PT 的估计值存在差异。水文干旱的较长时间尺度对应较大的 PT，反之亦然。造成这种模式的主要原因是不同时间尺度的干旱指数对干旱事件的响应灵敏度不同。从运行理论获得的 PT 最短；因此，运行理论可以提供保守的预警，以帮助预防和减轻干旱。我们的研究结果可以帮助干旱管理者根据气象预报选择有效的工具来管理水文干旱的早期阶段，从而最大程度地减少干旱灾害带来的负面影响。
