EVALUATING THE EFFECTS OF CONSTRUCTION ACTIVITIES ON STREAM FLOW AND WATER QUALITY
The objective of this study is to understand and predict the impact of residential development activities on stream hydrology and water quality and to assess the effectiveness of BMPs at study sites in Greenville County, South Carolina. Hydrologic, sediment, and nutrient data were collected from several streams that drain small catchments (~1 km2) with varying degrees of active development. Peak flows from disturbed catchments were up to two orders of magnitude greater, and sediment yields were up to three orders of magnitude greater than those from the undisturbed reference catchments. Several metal concentrations (e.g. Fe, Mn, Al, Mg, and K) follow a similar trend and were strongly correlated (R2 > 0.7) with the sediment. The effect of land use disturbance on stream hydrology was the greatest during the storms preceded by dry periods. Using the formulation of the Universal Soil Loss Equation, the product of cover-management factor (C) and support practice factor (P) is calculated for each land-use type. Relative values of this product (PC) for agricultural land = 1.3, forest land = -1.8, fully developed urban land = 5.7, and construction site = 146. This emphasizes the importance of taking land use interactions into account and estimating the extent of disturbance at the site instead of the overall disturbance at the scale of the watershed.
Distributed parameter models like SWAT and GSSHA were used to simulate the effects of land use disturbance in the study area. SWAT being physically discontinuous does not account for land use interactions while GSSHA being physically continuous does take them into account.