Drought Monitoring

As the world moves into the 21st century, the stresses on available water resources will continue to grow. In the United States, increasing growth and development are already straining water supplies not only for the major metropolitan areas of the arid West, but also for areas such as Atlanta, Georgia, in the relatively humid eastern United States. Issues surrounding shared water resources across international boundaries, such as the Colorado and Rio Grande River basins between the United States and Mexico and the Great Lakes and Columbia River basins between the United States and Canada, will also continue to grow. Droughts, as a normal natural hazard in most climates, will compound these concerns. Therefore, because of serious drought impacts on water resources-related issues, planning for and responding effectively to future droughts will be critically important.

A key component to drought risk management and to breaking the "hydro-illogical cycle" (illustrated in Chapter 5) is drought monitoring. Decision makers need timely and accurate information about the development of drought condi-tions—in effect, an early warning system so they can anticipate the onset of drought and be prepared. They also need accurate and timely assessments of drought severity so appropriate responses can be coupled with current or anticipated drought impacts. In addition, during drought recovery, decision makers need information that can document the status of recovery and identify if and when the event is over. Drought monitoring must be a continuous process so the hazard and its impacts do not creep up on a region. Decision makers would also benefit from short- and long-term drought forecasting tools that allow them to anticipate and respond to a drought episode with greater precision.

One constraint to effective drought monitoring has always been the lack of a universally accepted definition. Scientists and decision makers must accept that the search for a single definition of drought is a hopeless exercise. Drought definitions must be specific to the region, application, or impact. Drought must be characterized by many different climate and water supply indicators. Impacts are complex and vary regionally and on temporal timescales. As described by Steinemann et al. (Chapter 4), drought monitoring indicators, ideally, should be tied directly to triggers that assist decision makers with timely and effective responses before and during drought events.

The need for improved drought monitoring is highlighted by recent widespread and severe droughts that have resulted in serious economic, social, and environmental impacts in many countries. In the United States, these droughts have fostered development of improved drought monitoring data and tools and collaborations between scientists. This chapter discusses some of these new developments as well as the current status of drought forecasting in the United States.

Continue reading here: Past Efforts

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