Groundwater Flow Modeling in the Shallow Aquifer of Buffalo Creek, Greensboro

Abstract

U.S. Environmental Protection Agency categorized Buffalo Creek as one of the impaired waters in Cape Fear River Basin, North Carolina, due to high concentrations of metals and pathogens. These contaminants originate from effluents discharged from industries and agricultural activities. This study used a numerical groundwater flow modeling approach to investigate the surface and groundwater interaction in the Buffalo Creek watershed for the fate and transport of contaminants. The movement of groundwater flow was simulated using MODFLOW while the particle tracking was analyzed by the MT3D model. MODFLOW solves groundwater flow equation using the finite-difference approximation. The flow region which covers both North and South Buffalo Creek was subdivided into blocks or cells in which the medium properties were assumed to be uniform. The cells are made from a grid of mutually perpendicular lines that are variably spaced depending upon the location. Spatial locations and distributions of stream networks, elevations, boundary conditions (no flow and constant, variable head zones), existing well locations, and industrial as well as wastewater effluent discharge locations were developed within ArcGIS environment. The modeling tasks of this study are domain characterization (database for surface elevation and stream network), modeling setup, and calibration and validation of the model using observed data. The observed data for baseflow was obtained using the baseflow filter algorithm, which basically separates baseflow from streamflow based on nature of the hydrograph. The modeling setup and initial calibration results for the steady-state simulation are presented in this chapter.