Validating commonly used drought indicators in Kenya
Validating commonly used drought indicators in Kenya
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DOI：
10.1088/1748-9326/ac16a2
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发表时间：
2021-08
影响因子：
6.7
通讯作者：
Andrew Bowell;Edward E. Salakpi;Kiswendsida H. Guigma;James M. Muthoka;John Mwangi;P. Rowhani
中科院分区：
文献类型：
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作者：
Andrew Bowell;Edward E. Salakpi;Kiswendsida H. Guigma;James M. Muthoka;John Mwangi;P. Rowhani
干旱是一种复杂的自然灾害，可能发生在任何气候条件下，影响到社会的方方面面。为了更好地准备和减轻干旱的影响，可以应用各种指标来监测和预测干旱的发生、强度和严重程度。尽管这些指标被广泛使用，但人们对它们的功效知之甚少，这限制了它们在重要决策中的作用。在这里，我们提供了11个常用的干旱指标的第一次验证，通过比较他们在肯尼亚的地面上收集的牧场和浏览条件的数据。这些地面数据提供了对情况的绝对和相对评估，类似于某些干旱指标。重点干旱和半干旱土地的草和灌木丛，我们证明了地面牧场和浏览条件，卫星干旱指标之间有很强的关系。土壤调节植被指数具有最好的相关性，在绝对牧场条件下拟合时，平均R2得分为0.70。同样，3个月的植被健康指数达到了平均r 2得分为0.62时，适合对相对牧场条件。此外，我们还调查了肯尼亚干旱预警系统使用的3个月平均植被状况指数（VCI 3 M; VCI 3 M < 35）的全国干旱发生阈值。我们的研究结果显示，不同国家的阈值存在很大差异。了解这些关系和阈值是发展有效和高效干旱预警系统的必要条件。我们的工作为其中一些指标的有效性提供了证据，并为其使用提供了实际阈值。
Drought is a complex natural hazard that can occur in any climate and affect every aspect of society. To better prepare and mitigate the impacts of drought, various indicators can be applied to monitor and forecast its onset, intensity, and severity. Though widely used, little is known about the efficacy of these indicators which restricts their role in important decisions. Here, we provide the first validation of 11 commonly-used drought indicators by comparing them to pasture and browse condition data collected on the ground in Kenya. These ground-based data provide an absolute and relative assessment of the conditions, similar to some of the drought indicators. Focusing on grass and shrublands of the arid and semi-arid lands, we demonstrate there are strong relationships between ground-based pasture and browse conditions, and satellite-based drought indicators. The soil adjusted vegetation index has the best relationship, achieving a mean r 2 score of 0.70 when fitted against absolute pasture condition. Similarly, the 3-month vegetation health index reached a mean r 2 score of 0.62 when fitted against a relative pasture condition. In addition, we investigated the Kenya-wide drought onset threshold for the 3-month average vegetation condition index (VCI3M; VCI3M < 35), which is used by the country’s drought early warning system. Our results show large disparities in thresholds across different counties. Understanding these relationships and thresholds are integral to developing effective and efficient drought early warning systems. Our work offers evidence for the effectiveness of some of these indicators as well as practical thresholds for their use.