The Challenge of Drought Early Warning
A drought early warning and information system (DEWIS) is designed to identify trends of key meteorological, hydrological, and social indicators to predict both the occurrence and the impact of a particular drought and to elicit appropriate mitigation and response measures (Buchanan-Smith and Davies 1995; WMO and GWP 2014). For most locations, the continuum from drought forecasting to early warning is still a linear process based on a "sender-receiver" model of risk communication. In the following discussion, the phrase early warning information system is used to describe an i ntegrated process of risk assessment, communication, and decision support, of which an early warning is a central output. An early warning information system involves much more than development and dissemination of a forecast; it is the systematic collection and analysis of relevant information about, and coming from, areas of impending risk that (1) informs the development of strategic responses to anticipate crises and crisis evolution, (2) provides capabilities for generating problem-specific risk assessments and scenarios, and (3) effectively communicates options to critical actors for the purposes of decision-making, preparedness, and mitigation (Pulwarty and Verdin 2013).
The DEWIS when coupled with vulnerability assessments aimed at understanding and reducing risk becomes a powerful tool in risk reduction. The goal of a national drought policy is to define the overarching principles for the development of effective and timely programs that target risk reduction (see Chapter 4).
Numerous natural indicators of drought should be monitored routinely to determine drought onset, end, and spatial characteristics. Severity must also be evaluated continuously and at frequent time steps. Although droughts originate from a deficiency of precipitation, it is insufficient to rely only on this climate element to assess severity and resultant impacts. An effective DEWIS must integrate precipitation data with other data such as streamflow, snowpack, groundwater levels, reservoir and lake levels, and soil moisture in order to assess drought and water supply conditions (see Chapters 7, 8, and 9).
These physical indicators and climate indices must then be combined with socioeconomic indicators in order to predict human impact. Socioeconomic indicators include market data—for example, grain prices and the changing terms of trade between staple grains and livestock as an indicator of purchasing power in many rural communities—and other measures of coping strategies. Communities usually employ a sequence of strategies in response to drought. Early coping strategies rarely cause any lasting damage and are reversible. In many poor rural communities, examples of early coping strategies include the migration of household members to look for work, searching for wild foods, and selling nonproductive assets. If the impact of the drought intensifies, these early strategies become unviable and people are forced to adopt more damaging coping strategies, such as selling large numbers of livestock, choosing to go hungry or reduce nutritional sources of food in order to preserve some productive assets, and abandonment of traditional homelands. Once all options are exhausted, people are faced with destitution and resort to crisis strategies such as mass migration or displacement (Corbett 1988; Young et al. 2001). Monitoring these coping strategies provides a good indicator of the impact of drought on the local population, although by the time there is evidence of the later stages of coping, it is usually too late to launch a preventative response.
Effective DEWISs are an integral part of efforts worldwide to improve drought preparedness. Many DEWISs are, in fact, a subset of an early warning system with a broader remit—to warn of other natural disasters and sometimes also conflict and political instability. Timely and reliable data and information must be the cornerstone of effective drought policies and plans. Monitoring drought presents some unique challenges because of the hazard's distinctive characteristics, as noted previously.
An expert group meeting on early warning systems for drought preparedness, sponsored by the World Meteorological Organization (WMO) and others, examined the status, shortcomings, and needs of DEWISs and made recommendations on how these systems can help in achieving a greater level of drought preparedness (Wilhite et al. 2000b). This meeting was organized as part of WMO's contribution to the Conference of the Parties of the UN Convention to Combat Desertification (UNCCD). The proceedings of this meeting not only documented efforts in DEWISs in countries such as Brazil, China, Hungary, India, Nigeria, South Africa, and the United States, but also noted the activities of regional drought monitoring centers in eastern and southern Africa and efforts in West Asia and North Africa. Shortcomings of current DEWISs were noted in the following areas:
- • Data networks—Inadequate station density, poor data quality of meteorological and hydrological networks, and lack of networks on all major climate and water supply indicators reduce the ability to represent the spatial pattern of these indicators accurately.
- • Data sharing—Inadequate data sharing between government agencies and the high cost of data limit the application of data in drought preparedness, mitigation, and response. In 2017, this continues to be a serious problem in the majority of countries.
- • Early warning system products—Data and information products are often too technical and detailed. They are not accessible to busy decision makers who, in turn, may not be trained in the application of this information to decision-making.
- • Drought forecasts—Unreliable seasonal forecasts and the lack of specificity of information provided by forecasts limit the use of this information by farmers and others.
- • Drought monitoring tools—Inadequate indices exist for detecting the early onset and end of drought, although the SPI was cited as an important new monitoring tool to detect the early emergence of drought. Significant advances in drought monitoring tools have been made since this meeting was held in 2000. These advances are discussed in much greater detail in Chapter 8, Handbook on Drought Indices and Indicators, published by the Integrated Drought Management Programme (IDMP) of the WMO and the Global Water Partnership (GWP), and republished in this volume with the permission of WMO and GWP (see Chapter 8; WMO and GWP 2016).
- • Integrated drought/climate monitoring—Drought monitoring systems should be integrated and based on multiple physical and socioeconomic indicators to fully understand drought magnitude, spatial extent, and impacts. There has been considerable progress on this issue in some countries, as noted in numerous case studies included in this book.
- • Impact assessment methodology—Lack of impact assessment methodology hinders impact estimates and the activation of mitigation and response programs. This continues to be a shortcoming in most countries.
- • Delivery systems—Data and information on emerging drought conditions, seasonal forecasts, and other products are often not delivered to users in a timely manner.
- • Global early warning system—No historical drought database exists and there is no global drought assessment product that is based on one or two key indicators, which could be helpful to international organizations, nongovernmental organizations (NGOs), and others. There has been considerable advancement in attempts to develop a global drought monitoring system in recent years (see Chapter 6 in this book; Heim et al. 2017).
As documented in this volume, efforts to address these specific concerns are now being undertaken through the UN International Drought Management Program, the US National Integrated Drought Information System, and PRONACOSE in Mexico, among others. As has now been well established, early warning alone is not enough to improve drought preparedness. Effective early warning depends on a multisectoral and interdisciplinary collaboration among all concerned actors at each stage in the warning process, from monitoring to response and evaluation, and informs longer-term planning beyond emergency responses. The key is whether decision makers listen to the warnings and act on them in time to protect livelihoods before lives are threatened and use the opportunities to create more proactive policies. The links between community-based approaches and the national and global EWSs remain relatively weak. There are many reasons why this is often the "missing link" and has been referred to as "the last mile." For example, risk- averse decisionmakers may be reluctant to respond to predictions, instead waiting for certainty and quantitative evidence. This invariably leads to a late response to hard evidence that the crisis already exists. Who "owns" the early warning information is also critical to how it is used. Does it come from a trusted source, or is it treated with suspicion? Ultimately, sufficient political will must exist to launch a timely response and hence to heed the early warnings (Buchanan-Smith and Davies 1995; Wilhite et al. 2014). How the political will to act is derived in noncrisis situations remains an area in need of focused policy sciences research.