Oral Abstract Details

Author(s):
Kunwar K Singh, Craig Allan and Ross Meentemeyer

Affiliation:
Center for Applied Geographic Information Science, Department of Geography and Earth Sciences University of North Carolina at Charlotte, Charlotte

Presentation Type:
Oral

Topic Area:
Alteration of natural disturbances due to urbanization

Abstract Text:
Urbanization modifies the land surface by replacing vegetation and pervious soil surfaces with impervious materials. This process decreases infiltration into soils, delays or inhibits ground water recharge, and increases the amount of pollutants and volume of and rate at which water enters streams. Impervious surfaces in urban areas channelize storm water runoff into surrounding streams and change the timing, magnitude, and frequency of low and high flow events. These permanent alterations in the natural hydrologic regime commonly result in increases in the intensity and frequency of flash floods. Utilizing long-term streamflow data from both urban and rural streams in two watersheds of the Piedmont, NC, this study investigates the relationship of the variability of stream flow to changes in land cover. The approach involves a comparative analysis of long-term daily stream discharge characteristics of a highly urbanized watershed (Little Sugar Creek, Charlotte, Mecklenburg County, NC) and a less-urbanized watershed (Long Creek, Bessemer City, Gaston County, NC) in a similar geographical, geological, and hydrological setting using various flow indices. Degree of imperviousness ranges from 5% in less-urbanized to 90% in a highly urbanized watershed. The highly urbanized Little Sugar Creek watershed exhibited significantly higher flow frequency, decreased streamflow distribution, and increased daily discharge when compared to the less-urbanized watershed. Frequency of events greater than the 10th-percentile flow shows 55.21% increase (38.99 events per year in Little Sugar Creek and 25.12 events per year in Long Creek) in a highly urbanized stream, frequency of daily flow corresponding to annual peak flow is about two times in Little Sugar Creek stream in comparison to the Long Creek stream. The mean and median stream flow values are 19.17cf/s and 5.10cf/s in the Little Sugar Creek and 27.77cf/s and 16cf/s in Long Creek stream. Low mean and median flow represents the urbanization process. The results of this study suggest that urbanization and associated land cover change play significant roles in altering natural streamflow regimes and increase the magnitude and frequency of extreme flow events. Keywords: Streamflow, urbanization, flow indices.