Benefits of Action and Costs of Inaction: Drought Mitigation and Preparedness—A Literature Review

Introduction

Droughts are major natural hazards and have wide-reaching economic, social, and environmental impacts. Their complex, slow, and creeping nature; the difficulty of determining their onsets and endings; their site- dependence; and the diffuse nature of their damage (Below et al. 2007) makes the task of comprehensively and accurately determining the cost of droughts a highly challenging one. These difficulties are compounded by a lack of data on droughts and their impacts (Changnon 2003), especially in low-income countries.

Droughts are the most detrimental of all the natural disasters (Bruce 1994; Obasi 1994; Cook et al. 2007; Mishra and Singh 2010). Globally, about one-fifth of the damage caused by natural hazards can be attributed to droughts (Wilhite 2000), and the cost of droughts is estimated to be around USD 80 billion per year (Carolwicz 1996). In the United States—one of the few countries having relatively good data availability—the annual losses attributed to droughts were estimated to be around USD 6-8 billion in the early 1990s (Wilhite 2000, citing FEMA 1995). In the European Union, the damage caused by droughts is estimated to be around EUR 7.5 billion per year (CEC 2007; EC 2007). However, these estimates are likely to be quite conservative, since they often fail to take all the impacts into account. Indirect drought impacts in particular are seldom captured appropriately or systematically by drought monitoring and reporting systems. For example, in addition to affecting the quantity of water, droughts have negative effects on the quality of water systems. These effects include increased salinity, enhanced stratification leading to algal production and toxic cya- nobacterial blooms, higher turbidity, and deoxygenation (Webster et al. 1996; Mosley 2015). The costs of these water quality impacts are yet to be quantified adequately.

Importantly, droughts may also have far-reaching social and economic impacts—for example, by leading to conflict and civil unrest (Johnstone and Mazo 2011; von Uexkull 2014; Linke et al. 2015), migration (Gray and Mueller 2012), gender disparities (Fisher and Carr 2015), reduced hydroenergy generation (Shadman et al. 2016), food security and famine (IFRC 2006), poverty (Pandey et al. 2007), and negative short- and long-term health effects (Hoddinott and Kinsey 2001; Ebi and Bowen 2015; Lohmann and Lechtenfeld 2015). Conway (2008) indicates that between 1993 and 2003, drought-induced famines affected 11 million people in Africa. According to the World Meteorological Organization (WMO), droughts may have caused 280,000 human deaths between 1991 and 2000 globally (Logar and van den Bergh 2011). Other indirect impacts are mentioned in national post-disaster needs assessments supported by the Global Facility for Disaster Reduction and Recovery/World Bank and other technical and donor agencies, and extend to social (e.g., access to education) and environmental (e.g., loss of ecosystem services) issues (see for instance the reports from Kenya 2012, Djibouti 2011, and Uganda 2010-2011, available at https://www.gfdrr.org/post-disaster-needs-assessments). However, there is relatively little literature on the economic costs of such indirect impacts. Furthermore, indirect costs may increase to a greater extent than direct costs in the future because of increasing frequency and severity of droughts under climate change, and these will be particularly challenging to model (Jenkins 2011).

The difficulty of assessing the costs and impacts of droughts is complicated by the challenge of how to define drought. Drought is a temporary climatic feature, unlike aridity, which is a permanent characteristic of a climate (Wilhite 1992). Drought has numerous definitions, which may be mutually incompatible. Ideally, the definition should be set specifically for each location, taking into account the characteristics of that location (Wilhite and Glantz 1985).

Drought is a natural hazard, so its occurrence in any location and during a given time period could be evaluated by attaching probabilities depending on the biophysical and climatic characteristics of that location (Wilhite 2000). However, drought impacts are strongly modulated by the socioeconomic characteristics of affected areas, such as their vulnerability and resilience to drought, as well as their level of drought preparedness. The role of socioeconomic factors in determining drought impacts is complex and relations are not linear; for example, a higher level of socioeconomic development and water services infrastructure can mitigate or exacerbate the impacts of drought.

In a risk-based approach to drought (described in this study as drought risk management), we refer to mitigation of the risk of incurring negative impacts from drought events, rather than reducing the probability of occurrence of drought events. In this sense, vulnerability to drought is the susceptibility to be negatively affected by drought (Adger 2006), with the opposite being resilience, that is, the ability to cope successfully with drought and overcome its impacts. Vulnerability and resilience to drought are affected by actions taken to mitigate drought impacts and increase drought preparedness (Wilhite et al. 2014). These both reflect the degree of adaptive capacity of a community (Engle 2013). Drought preparedness involves actions undertaken before drought occurs and that will improve operational and institutional response to drought (Kampragou et al. 2011).

On the other hand, drought impact mitigation actions include a variety of activities carried out before drought occurs that will minimize the impacts of drought on people, the economy, and the environment. Wilhite et al. (2005) classified actions for drought preparedness in a 10-step process. This has been further refined for national drought management policies by WMO and GWP (2014). Based on the High-level Meeting on National Drought Policy (WMO et al. 2013), the integrated drought management programme (IDMP) and its partners have adopted three pillars of drought management: (1) drought monitoring and early warning systems; (2) vulnerability and impact assessments; and (3) drought preparedness, mitigation, and response.

The difficulty of accurately assessing the costs of droughts presents substantial challenges for the analysis of the costs and benefits of investments made and policy actions taken against droughts. At the same time, droughts are not weather or climatic anomalies, but a recurrent and normal feature of almost any climate (Kogan 1997), even in comparatively water-rich countries (Kampragou et al. 2011). NCDC (2002) indicates that about 10 percent of the territory of the United States is affected by drought at any given time. Between 2000 and 2006, 15 percent of the European Union's land area was affected by drought

(Kampragou et al. 2011), more than double the annual average for 1976-1990 (EC 2007). Droughts have occurred in different locations across Vietnam in 40 out of the past 50 years (Lohmann and Lechtenfeld 2015). Gan et al. (2016) provide an extensive review of climate change and variability in drought-prone areas of Africa and predicts critical negative impacts on a wide variety of drought- related indicators. Given the scale of the issue and the likely drought trends under climate change, it is essential to have a well-defined strategy for mitigating the impacts of drought and enhancing drought preparedness.

However, the default course of action used by many countries is to respond to the impacts of droughts once they have occurred, through drought relief (i.e., crisis management), rather than proactively improving resilience through appropriate risk management strategies (Wilhite 1996). Crisis management approaches usually fail to reduce future vulnerability to drought. On the contrary, by providing drought relief to activities that are vulnerable to drought, they may in fact incentivize their perpetuation. As a result, continued vulnerability makes crisis management costlier to society than ex ante investments that mitigate drought risks by building resilience. Moreover, since we currently lack comprehensive assessments of the full social and environmental costs of droughts, the ultimate costs of continued vulnerability are likely to be higher than estimated at present. Furthermore, climate change is expected to increase the frequency and severity of droughts (Stahl and Demuth 1999; Andreadis and Lettenmaier 2006; Bates et al. 2008). The changing climate is also likely to expand the geographical extent of drought- prone areas (Mishra and Singh 2009; IPCC 2014), making crisis management approaches even less affordable than they are today. This begs the question: if proactive risk management is socially optimal compared with reactive crisis management, why is the shift from crisis management to risk management happening so slowly?

This review seeks to shed light on responses to this question by evaluating current relevant literature. More specifically, we seek to summarize the key literature on the costs and benefits, and pros and cons, of reactive public crisis management versus ex ante government policies for drought risk management directed toward investment in mitigation actions and drought preparedness that reduce the impacts of future droughts. We also identify the obstacles and opportunities facing the transition from crisis management to risk management, presenting country experiences from around the world. In this regard, the findings highlight that many drought risk management actions and investments have substantial cobenefits and positive social returns even without droughts. Hence, they can be promoted widely as low- or no-regret strategies for sustainable development and building resilience to a variety of environmental, economic, and social shocks. Finally, this review discusses the major existing research and knowledge gaps in current drought-related literature and policy actions.

Selection of literature for this review was based on searches in Google Scholar and ScienceDirect platforms using the word drought in combination with other key words such as vulnerability, resilience, early warning and monitoring, impacts, risk management, and crisis management. IDMP partners and participants in the IDMP Expert Group Meeting on this topic in September 2016 (see Acknowledgments) also provided key references. Moreover, citations in key documents were followed to identify additional relevant publications. This review did not cover every aspect of the drought literature in detail, but focused on publications of most relevance to the specific research question mentioned above. Although peer-reviewed papers, institutional publications, and unpublished sources were included, we gave peer-reviewed papers a higher preference in shaping the conclusions of the review, while institutional publications served as valuable background material and sources of further reading.

 
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