How does this drought compare to other droughts we have had? Is it severe and how long do they usually last?
Posted October 16, 2007 12:26 p.m. EDT
Updated October 16, 2007 12:29 p.m. EDT
MIKE MOSS SAYS: Sarah, This year's drought is one of the most severe (now rated exceptional for more than half the counties in the state) on record for much of North Carolina. It can be a little difficult comparing one drought to another in a simple manner, because they may have different characteristics in terms of how the combination of duration and peak intensity affects agriculture, streamflows, groundwater levels, surface water supplies, and so forth, and impacts may also vary depending on temperature and evaporation rates, along with water demand which can vary with population and according to the responses in the form of water use restrictions and the like.
Nonetheless, the drought of 1998-2002 (most severe in our area from late 2001 into mid 2002) has been regarded as one of the worst in our state's history, with many record low streamflow rates and groundwater levels observed. The drought we are in now has produced new records for low streamflow at some sites that have exceeded even the 2002 levels, and a commonly used descriptor for drought, called the Palmer Drought Severity Index, has rapidly fallen to some of the lowest (driest) values seen in averages of this index for North carolina and for the climate division that includes Wake County. Whether in the end this drought will exceed the overall impact of all earlier droughts on record will depend on when and how rapidly we recover from it. Droughts usually last from about one to four years, and it is difficult to accurately predict when a particular drought will break.