Chapter 1The Enigma of Drought
Donald Wilhite1993
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The Enigma of Drought
Drought Assessment, Management, and Planning: Theory and Case Studies, 1993
Understanding: the Drought Phenomenon: The Role of Definitions
Water International, 1985
Droughts: The impact of semantics and perceptions
Water Policy, 2008
Global environmental change coupled with increased demand for food and competition for diminishing water places the issue of disaster risk management high on the global political agenda. Drought is one of the most Q1 complex natural hazards, affecting natural resources and human development recurrently. Drought affects agricultural production globally, triggering significant food and health insecurity and habitat loss through land degradation and desertification. While the consequences of droughts can usually be predicted, preventive action is frequently absent or insufficient to prevent serious impacts in many regions of the world. We believe that lack of a common understanding of what drought is stands in the way of cohesive anti-drought action. This paper examines drought definitions emerging from influential scholarship, practitioners' discourse and multilateral policy processes that emphasise diverging aspects of the phenomena of dry periods, including the source, duration, spatial extent, impact and affected stakeholders. This paper begins by examining the concepts of hazard and disaster. It then explores the various perceptions associated with drought and the problems posed by inconsistency in definitions. It concludes that a common conceptual understanding of drought is essential for effective action to address the growing need for reliable food supply, poverty alleviation and increased agricultural productivity globally.
How ecologists define drought, and why we should do better
Global Change Biology, 2019
Drought, widely studied as an important driver of ecosystem dynamics, is predicted to increase in frequency and severity globally. To study drought, ecologists must define or at least operationalize what constitutes a drought. How this is accomplished in practice is unclear, particularly given that climatologists have long struggled to agree on definitions of drought, beyond general variants of "an abnormal deficiency of water". We conducted a literature review of ecological drought studies (564 papers) to assess how ecologists describe and study drought. We found that ecologists characterize drought in a wide variety of ways (reduced precipitation, low soil moisture, reduced streamflow, etc.), but relatively few publications (~32%) explicitly define what are, and are not, drought conditions. More troubling, a surprising number of papers (~30%) simply equated "dry conditions" with "drought" and provided little characterization of the drought conditions studied. For a subset of these, we calculated Standardized Precipitation Evapotranspiration Index values for the reported drought periods. We found that while almost 90% of the studies were conducted under conditions quantifiable as slightly to extremely drier than average, ~50% were within the range of normal climatic variability. We conclude that the current state of the ecological drought literature hinders synthesis and our ability to draw broad ecological inferences because drought is often declared but is not explicitly defined or well characterized. We suggest that future drought publications provide at least one of the following: 1) the climatic context of the drought period based on long-term records, 2) standardized climatic index values, 3) published metrics from drought monitoring organizations, 4) a quantitative definition of what the authors consider to be drought conditions for their system. With more detailed and consistent quantification of drought conditions, comparisons among studies can be more rigorous, increasing our understanding of the ecological effects of drought.
Propagation of Drought: From Meteorological Drought to Agricultural and Hydrological Drought
Advances in Meteorology, 2016
Drought: A Common Environmental Disaster
Atmosphere, 2022
Droughts have been identified as an environmental hazard by environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural experts. Droughts are characterised by a decrease in precipitation over a lengthy period, such as a season or a year, and can occur in virtually all climatic zones, including both high and low rainfall locations. This study reviewed drought-related impacts on the environment and other components particularly, in South Africa. Several attempts have been made using innovative technology such as earth observation and climate information as recorded in studies. Findings show that the country is naturally water deficient, which adds to the climate fluctuation with the average annual rainfall in South Africa being far below the global average of 860 mm per year. Drought in South Africa’s Western Cape Province, for example, has resulted in employment losses in the province’s agriculture sector. According to the third quarterly labor force sur...
The enigma of drought: management and policy issues for the 1990s
International Journal of Environmental Studies, 1990
Drought affects more people than any other hazard, in both developed and developing countries, yet few governments have taken steps to prepare for it. This situation stems partly from the complex nature of drought, which affects various sectors of society in different ways, and partly from an inability or unwillingness of governments to accept drought as a normal part of climate, not as an extreme random event. Scientific and policy communities have become increasingly concerned about the inability of governments to respond to drought in an effective and timely manner, and some have called for improved drought planning and management. This paper discusses planning as a means to reduce societal vulnerability to drought and outlines an approach that governments and international organizations can follow to prepare for severe drought. The basis of this approach is a ten-step planning process created from recommendations made at the 1986 International Symposium and Workshop on Drought. The status of drought planning worldwide is also discussed.
Defining Ecological Drought for the Twenty-First Century
Bulletin of the American Meteorological Society, 2017
DECEMBER 2017 AMERICAN METEOROLOGICAL SOCIETY | THE RISING RISK OF DROUGHT. Droughts of the twenty-first century are characterized by hotter temperatures, longer duration, and greater spatial extent, and are increasingly exacerbated by human demands for water. This situation increases the vulnerability of ecosystems to drought, including a rise in drought-driven tree mortality globally (Allen et al. 2015) and anticipated ecosystem transformations from one state to another-for example, forest to a shrubland (Jiang et al. 2013). When a drought drives changes within ecosystems, there can be a ripple effect through human communities that depend on those ecosystems for critical goods and services (Millar and Stephenson 2015). For example, the "Millennium Drought" (2002-10) in Australia caused unanticipated losses to key services provided by hydrological ecosystems in the Murray-Darling basin-including air quality regulation, waste treatment, erosion prevention, and recreation. The costs of these losses exceeded AUD $800 million, as resources were spent to replace these services and adapt to new drought-impacted ecosystems (Banerjee et al. 2013). Despite the high costs to both nature and people, current drought research, management, and policy perspectives often fail to evaluate how drought affects ecosystems and the "natural capital" they provide to human communities. Integrating these human and natural dimensions of drought is an essential step toward addressing the rising risk of drought in the twenty-first century. Part of the problem is that existing drought definitions describing meteorological drought impacts (agricultural, hydrological, and socioeconomic) view drought through a human-centric lens and do not fully address the ecological dimensions of drought.
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Defining ecological drought for the 21st century
Bulletin of the American Meteorological Society
Drought: Science And Policy
2019
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Chapter Eighteen DROUGHT : ITS PHYSICAL AND SOCIAL DIMENSIONS
2016
Drought has been a threat to human existence throughout history. Today, as in the past, drought alters the course of civilizations. It is not merely a physical phenomenon, but the result of an interplay between a natural event (precipitation deficiencies due to natural climatic variability on varying timescales) and the demand placed on water supply by human-use systems. Extended periods of drought have resulted in significant economic, environmental, and social impacts, including food supply disruptions, famine, massive soil erosion, migrations of people, and wars. Human activities often exacerbate the impacts of drought (e.g., the Dust Bowl in the Great Plains, the Sahelian drought of the early 1970s). This trend appears to be accelerating because of the increasing demand being placed on local and regional water resources as a result of the earth's rapidly expanding population. Recent droughts in developing and developed countries and the concomitant impacts and personal hardships that resulted have underscored the vulnerability of all societies to this natural hazard. It is difficult to determine whether it is the frequency of drought that is increasing, or simply societal vulnerability to it.
Drought in a human-modified world: reframing drought definitions, understanding and analysis approaches
Hydrology and Earth System Sciences Discussions, 2016
In the current human-modified world, or "Anthropocene", the state of water stores and fluxes has become dependent on human as well as natural processes. Water deficits (or droughts) are the result of a complex interaction between meteorological anomalies, land surface processes, and human inflows, outflows and storage changes. Our current inability to adequately analyse and manage drought in many places points to gaps in our understanding and to inadequate data and tools. The Anthropocene requires a new framework for drought definitions and research. Drought definitions need to be revisited to explicitly include human processes driving and modifying soil moisture drought and hydrological drought development. We give recommendations for robust drought definitions to clarify timescales of drought and prevent confusion with related terms such as water scarcity and overexploitation. Additionally, our understanding and analysis of drought need to move from single driver to mult...
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