Review Simulation of land use impacts on groundwater levels and streamflow in a Virginia watershed J. Cho a,b, *, V.A. Barone a , S. Mostaghimi a a Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, 200 Seitz Hall (0303), Blacksburg, VA 24060, USA b USDA–ARS, SEWRL, 2375 Rainwater Road, Tifton, GA 31794, USA agricultural water management 96 (2009) 1–11 article info Article history: Received 9 January 2008 Accepted 15 July 2008 Published on line 23 August 2008 Keywords: Surface water Groundwater Interactions Hydrology Modeling Land use planning Urbanization Watershed management MODFLOW HSPF Upper Roanoke River Watershed Back Creek watershed abstract Increase in withdrawal and decrease in recharge of groundwater due to urbanization influences subsurface flow regimes. The overall objective of this study was to determine the impact of land development activities on the subsurface flow regime in the Upper Roanoke River Watershed (URRW). A regional groundwater model of the URRW was con- structed using Modular Three-Dimensional Ground-Water Flow Model (MODFLOW) and calibrated for steady-state conditions. Then, eight land use management scenarios were simulated on the Back Creek (BC) subwatershed to assess the impacts of residential density, residential location, and land-cover on hydraulic head of groundwater and streamflow. The average recharge output from the Hydrological Simulation Program, FORTRAN (HSPF) simulation was used as the direct input to MODFLOW to take changes in land use into account in the BC watershed. Development of agriculture and forest areas with low- population density on larger area (low-density scenario), near the middle of the watershed (mid-section scenario), and with changes all open space to lawn (lawn scenario) had greatest overall impact on the BC watershed for both hydraulic head and streamflow among density, location, and land-cover scenarios, respectively. The simulated scenarios indicated that decreases in both hydraulic head and streamflow coincided with the increases in imper- vious land. The reductions in hydraulic head and streamflow were restricted to the sub- watershed where land use changes occurred. The urbanization impacts on both surface and subsurface regimes were very local with 20.8 cm of maximum difference in local hydraulic head and 0.532% of maximum percent difference in local streamflow at lawn scenario while average corresponding values through BC watershed was 4.3 cm and 0.153%, respectively. Use of a fully distributed surface model in a dynamic manner was recommended to solve the inconsistencies in the spatial and temporal scale of surface and groundwater models. However, the proposed approach can be used as a management and planning tool for evaluating the local and overall impacts of land use management on the surface and subsurface flow regimes. # 2008 Elsevier B.V. All rights reserved. * Corresponding author at: USDA–ARS, SEWRL, 2375 Rainwater Road, Tifton, GA 31794, USA. Tel.: +1 229 391 6854; fax: +1 229 386 3958. E-mail addresses: jcho@vt.edu (J. Cho), vbarone@180s.com (V.A. Barone), smostagh@vt.edu (S. Mostaghimi). available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/agwat 0378-3774/$ – see front matter # 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.agwat.2008.07.005