Effects of August 1995 and July 1997 Storms in the City of Charlotte and Mecklenburg County, North Carolina

Prepared in cooperation with the City of Charlotte and Mecklenburg County

FLOODING IN THE CITY OF CHARLOTTE AND MECKLENBURG COUNTY AS A RESULT OF THE STORMS OF AUGUST 26-28, 1995, AND JULY 22-24, 1997

Flooding that resulted from the August 1995 storm was greatest in the Briar, McMullen, and McAlpine Creek Basins in southeast Charlotte where rainfall amounts were greatest and generally exceeded 6 inches (fig. 2). Peak flows in the McAlpine Creek Basin exceeded the 100-year recurrence interval at both streamflow gaging stations. Although rainfall amounts in the Irwin Creek Basin were generally 4 to 6 inches during the storm, the peak flow at the Irwin Creek streamflow gaging station had a recurrence interval of 5 to 10 years (table 3).

In comparison, the upstream part of the Irwin Creek Basin received 7 to 10 inches of rain during the July 1997 storm, and the peak flow at the Irwin Creek gage had a recurrence interval of 100 years. During the 1997 flood, water levels increased by 20 feet or more in Irwin Creek near Charlotte and in Little Sugar Creek near Pineville. Likewise, water levels increased by more than 10 feet at 10 of the 16 streamflow gaging stations (table 3). The change in water level in Little Sugar Creek at Medical Center Drive, relative to the bridge crossing, is depicted in figure 6.

Peak flows can move downstream rapidly during extreme events (fig. 7), and flooding can occur with little or no time for people to prepare. The USGS, in cooperation with Charlotte-Mecklenburg Stormwater Services, is currently (1998) investigating technologies that can be added to the existing data-collection network to facilitate early warning of possible flooding.