Exploring drought vulnerability in Africa: an indicator based analysis to be used in early warning systems

Abstract

Abstract. We propose a composite drought vulnerability indicator (DVI) that reflects different aspects of drought vulnerability evaluated at Pan-African level for four components: the renewable natural capital, the economic capacity, the human and civic resources, and the infrastructure and technology. The selection of variables and weights reflects the assumption that a society with institutional capacity and coordination, as well as with mechanisms for public participation, is less vulnerable to drought; furthermore, we consider that agriculture is only one of the many sectors affected by drought.The quality and accuracy of a composite indicator depends on the theoretical framework, on the data collection and quality, and on how the different components are aggregated. This kind of approach can lead to some degree of scepticism; to overcome this problem a sensitivity analysis was done in order to measure the degree of uncertainty associated with the construction of the composite indicator. Although the proposed drought vulnerability indicator relies on a number of theoretical assumptions and some degree of subjectivity, the sensitivity analysis showed that it is a robust indicator and hence able of representing the complex processes that lead to drought vulnerability.According to the DVI computed at country level, the African countries classified with higher relative vulnerability are Somalia, Burundi, Niger, Ethiopia, Mali and Chad. The analysis of the renewable natural capital component at sub-basin level shows that the basins with high to moderate drought vulnerability can be subdivided into the following geographical regions: the Mediterranean coast of Africa; the Sahel region and the Horn of Africa; the Serengeti and the Eastern Miombo woodlands in eastern Africa; the western part of the Zambezi Basin, the southeastern border of the Congo Basin, and the belt of Fynbos in the Western Cape province of South Africa.The results of the DVI at the country level were compared with drought disaster information from the EM-DAT disaster database. Even if a cause-effect relationship cannot be established between the DVI and the drought disaster database, a good agreement is observed between the drought vulnerability maps and the number of persons affected by droughts.These results are expected to contribute to the discussion on how to assess drought vulnerability and hopefully contribute to the development of drought early warning systems in Africa.

Exploring the link between drought indicators and impacts

“…Depending on the vulnerability of a system a given hazard intensity will or will not evoke adverse environmental, economic or social effects. Vulnerability assessment is a common tool for closing the gap between hazard information and knowledge of risk of a certain region or exposed entity (e.g., Birkmann et al, 2013;Kallis, 2008;Knutson et al, 1998); its outcome, however, will strongly depend on the quality of available indicator data and assumptions made (Naumann et al, 2014). Directly evaluating drought indicators with impact occurrence allows, in theory, gaining insight into the cause-effect relationship of a physical water deficit without any assumptions on vulnerability.…”

Reconciling Drought Vulnerability Assessment Using a Convergent Approach: Application to Water Security in the Elqui River Basin, North-Central Chile

“…Likewise, Carrão et al [33], in a global mapping of drought risk, understand drought vulnerability as "a reflection of the state of the individual and collective social, economic and infrastructural factors of a region at hand". In some way or another, the contextual framework has prevailed in studies of drought vulnerability, from the early work of Keenan and Krannich [34] and Wilhelmi and Wilhite [35] to more recent ones carried out by Naumann et al [31] and Carrão et al [33], as corroborated by Zarafshani et al [16] in their latest review of the topic. This fact reveals that the use of integral frameworks such as the one adopted in this study has been practically non-existent in the discussion and proposals aimed at the construction of standard approaches for drought vulnerability assessment [6].…”

“…This definition is clearly consistent with the contextual approach, because vulnerability is associated with the study of the characteristics that would make the object under analysis susceptible to harm. This approach is shared by Naumann et al [31], who address the study of drought vulnerability in Africa by understanding "the underlying causes of vulnerability". Shiferaw et al [32] adopt a similar approach when they conceive drought vulnerability as "the socioeconomic and biophysical characteristics of the region that make it susceptible to the adverse effects of drought".…”

“…In the case of drought, several studies have assessed the vulnerability to this socio-natural disaster following this approach [31][32][33][34][35][44][45][46]. From a quantitative point of view, most of these studies establish vulnerability metrics based on so-called composite indicators (CI) [47,48].…”

A Combined Satellite-Derived Drought Indicator to Support Humanitarian Aid Organizations

“…However, with regard to the overall risk assessment Ethiopia only ranks 63rd, because exposure (people and assets that can potentially be affected) towards natural disasters is comparatively low. In contrast, the drought vulnerability index of Naumann et al [23] classifies Ethiopia as highly vulnerable due to very weak renewable natural capital, weak economic capacity (including food security), weak human/civic resources and a dependency on unreliable rainfall patterns, which are predicted to further depart from the "normal" pattern [24].…”