Impacts of urbanization on stormflow magnitudes in small catchments in the Sandhills of South Carolina, USA

•Urbanization is a critical cause of growing flood risks on the Atlantic Coastal Plain.•Urban runoff and peak discharge were an order of magnitude larger than forested.•Urban runoff coefficients were an order of magnitude larger than forested.•Urban hydrographs had higher kurtosis although skewness was unchanged.•Stormwater in sandy, forested catchments is highly sensitive to urbanization.