As of January 1st, much of central North Carolina is considered to be in a moderate drought. People keep asking why since we’ve had what seemed to be plenty of rain over the last year. In fact, RDU International Airport recorded 40.79 inches of rain over the course of 2012. Our “normal” amount for a year is 43.34 inches. The question I keep getting is “if we’ve had rain, why are we in a drought?”
Being in a drought means more than just experiencing a long-term lack of rain. A lack of humidity and an extended period of wind can add to the problem at the surface, but one of the characteristics of drought that most people overlook is what is happening below the surface in the underground water supply. Rain that falls and quickly runs off into streams and tributaries is carried downstream. It does very little for the immediate area because it doesn’t have time to soak into the ground and add to the subterranean water level.
Often when we’ve had a week or more of dry weather and then get an afternoon of heavy rain, the dry soil is too hard to soak up the water as fast as it falls. So, the rain runs off. On the other hand, when the soil is saturated after days of steady rain, there tends to be more runoff because the earth can’t absorb any more water than it already has. We see the immediate effects of these two circumstances in rapidly rising streams and, in extreme cases, flooding.
Drought is the potential effect that takes longer to show itself. It’s a long-term problem that requires more than just a short-term solution. So, while we’ve had what seems like plenty of rain over the course of the last year, where that rain has gone – into the streams, creeks, and rivers to be carried to the ocean, or down into the earth below us – is what matters most.
The U.S. Drought Monitor looks at all of the ingredients that go into drought and issues a weekly update and map. The map is released to the public every Thursday on the Drought Monitor’s homepage, and it is a quick and easy way to track how we’re doing.