Simulating the Impact of Land Use Activities on Subsurface Flow Regime Using MODFLOW

Abstract

The MODFLOW was calibrated on the Upper Roanoke River Watershed (URRW) in a steady-state condition against measured hydraulic head and streamflow. Input data have been compiled for the study area to develop a conceptual model. Boundary and initial conditions are constructed on the Back Creek (BC) watershed based on the result of steady-state model. HSPF model was employed to obtain the average recharge values, which conceptually account for changes of land use in the BC watershed. The output from HSPF simulation was used as the direct input to the MODFLOW. A number of land use management scenarios were defined and simulated on the BC watershed to assess the land use impacts on hydraulic head and streamflow. The results of scenarios were compared to the baseline simulation that represents a current land use condition. The simulated scenarios showed that decreases of both hydraulic head and streamflow coincided with the increases of impervious land. However, the urbanization impacts on both regimes were not significant. Distributed modeling approaches are necessary to consider the distance from impervious land to the stream, which is a considerable factor to assess the impacts of development on streamflow.