Kansas Geological Survey, Open-file Report 2012-18
by
Anthony L. Layzell
KGS Open File Report 2012-18
Periods of severe drought are one of the greatest recurring natural disasters in North America. In any given year, droughts occur all across North America resulting in significant impacts on local economies, societies, and the natural environment. Drought conditions in the United States cost on average $6-8 billion every year, but have ranged as high as $39 billion during the three-year drought of 1987-89 (Riebsame et al., 1991). In Kansas alone, the recent 2011 drought resulted in losses in excess of $1.7 billion (Kansas Department of Agriculture, 2011).
Droughts impact both surface- and ground-water resources and often result in reductions in water supply and crop failure particularly in agriculturally sensitive areas such as the High Plains of western Kansas. This region is becoming increasingly vulnerable to drought due to a variety of factors including the increased cultivation of marginal lands and the increased use of ground-water resources from the High Plains aquifer (Woodhouse and Overpeck, 1998), where water withdrawal has exceeded recharge for many years (e.g. McGuire, 2009).
The droughts of the 1930s and the 1950s remain the benchmarks in terms of duration, severity, and spatial extent for Kansas in the 20th century. Therefore, determining how representative these historic droughts have been in terms of drought occurrence is vitally important. The key question is how unusual are severe droughts, such as the Dust Bowl? Was this drought a rare event or should we expect droughts of similar or even greater magnitude in the future? Direct observations of temperature and precipitation from instrumental records are largely restricted to the past 100 years and are therefore too short to adequately answer these questions. Therefore, in order to assess the full range of drought variability, it is important to place historic droughts in a longer-term context by utilizing paleoclimate proxy records.
This report investigates past drought occurrences from paleoclimate records over the last 1000 years. In particular, we focus on Palmer Drought Severity Index (PDSI) reconstructions calculated from annual tree-ring chronologies. Additional paleoclimate proxies and historical records are also examined to lend further support to reported past drought variability.
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Kansas Geological Survey
Updated Oct. 23, 2012
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