EFFECTS OF THE CURRENT DROUGHT ON STREAMFLOW AND GROUND-WATER CONDITIONS IN NORTH CAROLINA

Exceptional drought conditions prevailed across much of North Carolina during 2007, resulting in widespread record-low streamflow and ground-water levels. Droughts of longer duration have occurred previously in North Carolina, most recently in 1998-2002. The 1998-2002 drought has been regarded as the most intense on record, causing severe stress on water-supply systems, agricultural production, and recreational use of lakes and reservoirs. However, recent assessments of drought indicators by the State Climate Office of North Carolina indicate that the current drought is the worst recorded since weather records began in the late 1800's.

In cooperation with Federal, State, county, and local government agencies, the U.S. Geological Survey (USGS) monitors streamflow and ground-water levels throughout North Carolina. The USGS network of monitoring stations provides real-time streamflow at 219 stations, rainfall at 135 stations, and ground-water levels at 59 stations. These sites continuously record data at 15-minute (streamflow and rainfall) or 60-minute (ground water) intervals, and transmit the data by satellite or UHF radio to the USGS National Water Information System. Real-time monitoring data can be accessed at http://waterdata.usgs.gov/nc/nwis/.

Of the 219 USGS streamflow sites in North Carolina, 95 have more than 30 years of uninterrupted record through 2007 (23 of 95 sites are affected by regulation or diversion). In December 2007, 14 of the 95 long-term sites (15 percent) had provisional new minimum daily-mean discharges for the period of record, and 31 sites (33 percent) had lower minimum daily-mean discharges than were recorded during the 1998-2002 drought.

Of the 59 USGS ground-water-monitoring sites used to assess drought conditions, 16 sites have more than 15 years of record through 2007 and are not affected by local pumping. In December 2007, 5 of the 16 monitoring wells (31 percent) had provisional new low water levels for the entire period of record, and 8 wells (50 percent) had a lower minimum daily water level than was recorded during the 1998-2002 drought.

Drought-monitoring data for streamflow and ground-water-level sites can be accessed at http://nc.water.usgs.gov/drought/.