Two-Dimensional Mapping of Dynamic Watershed Response to Increasing Development in Fort Bend County, Texas

The Big Creek Watershed located in Fort Bend County, Texas is an undeveloped, low-slope area that experiences the pressure of future development on the western frontier of Houston. Urbanization exacerbates inundation in flood-prone areas as land use changes increase impervious surface area, decrease rainfall infiltration, and intensify flooding. Recent extreme flooding events in the Greater Houston area including the 2015 Memorial Day storm and Hurricane Harvey emphasize the importance of determining accurate floodplain extents for planning future development. Big Creek is a sparsely monitored watershed with two USGS streamflow gages covering an area of approximately 570 square kilometers during intermittent periods of record. A two-dimensional hydraulic model was developed to address this lack of data by creating design storm floodplain maps that provide useful feedback for county officials. The hydrodynamic model was calibrated using historic storms that caused substantial peak discharges within the watershed. Current and projected land use data were used to model the increase in floodplain extents as urbanization in the watershed increases. The study results demonstrate the effects of urbanization in the area and encourage officials to deter development in hazardous areas and mitigate flood risk for the community.