State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China; Key Laboratory for Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875, China.
State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, China.
Sci Total Environ. 2023 Jun 10;876:162771. doi: 10.1016/j.scitotenv.2023.162771. Epub 2023 Mar 11.
Propagation thresholds that trigger a transition between meteorological drought and hydrological drought are poorly understood, which hinders effective establishment of drought warning systems and prevention measures. Here, propagation thresholds were assessed by firstly identifying drought events during 1961-2016 in the Yellow River Basin, China, subsequently pooling, excluding, and matching them, and finally assessing their threshold conditions by using a combined Copula function and transition rate (T) analysis. These results show that response time changed according to variations in drought duration and watershed characteristics. Importantly, response times increased according to the timescales over which they were studied; for example, the Wenjiachuan watershed recorded response times of 8, 10, 10, and 13 months when examined at 1-, 3-, 6-, and 12-month timescales, respectively. Additionally, the severity and duration of meteorological and hydrological drought events both increased when events were combined rather than studied individually. These effects were also amplified for matched meteorological and hydrological droughts by factors of 1.67 (severity) and 1.45 (duration), respectively. Shorter response times were identified in the Linjiacun (LJC) and Zhangjiashan (ZJS) watersheds, and correlated with their relatively small T values of 43 % and 47 %, respectively. Higher propagation thresholds for drought characteristics (e.g., 1.81 and 1.95 for drought severity in the LJC and ZJS watersheds, respectively) imply that shorter response times tended to have greater effects on hydrological drought events and lowered their T, and vice versa. These results provide new insight into propagation thresholds used for water resource planning and management, and may help to mitigate the effects of future climate change.
引发气象干旱和水文干旱之间转变的传播阈值了解甚少，这阻碍了干旱预警系统和预防措施的有效建立。在这里，首先通过识别中国黄河流域 1961-2016 年期间的干旱事件，评估了传播阈值，然后汇集、排除和匹配它们，最后通过联合 Copula 函数和转移率（T）分析评估其阈值条件。这些结果表明，响应时间根据干旱持续时间和流域特征的变化而变化。重要的是，响应时间随着研究的时间尺度而增加；例如，当在 1、3、6 和 12 个月的时间尺度上研究时，文家川流域记录的响应时间分别为 8、10、10 和 13 个月。此外，当组合而不是单独研究时，气象和水文干旱事件的严重程度和持续时间都增加了。这些影响通过分别为 1.67（严重程度）和 1.45（持续时间）的因素放大了匹配的气象和水文干旱。林家村（LJC）和张家山（ZJS）流域的响应时间较短，与它们相对较小的 T 值 43%和 47%分别相关。干旱特征的传播阈值较高（例如，LJC 和 ZJS 流域的干旱严重程度分别为 1.81 和 1.95）意味着较短的响应时间往往对水文干旱事件有更大的影响，降低了它们的 T，反之亦然。这些结果为水资源规划和管理提供了新的见解，并可能有助于减轻未来气候变化的影响。
