The Big Creek Watershed located in Fort Bend County was severely inundated during Hurricane Harvey as 6,800 homes were damaged and 10,000 rescues were conducted. The Big Creek Watershed 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, especially floodplains, as land use changes increase impervious surface area, decrease rainfall infiltration, and intensify flooding. Therefore, it is critical to understand how the floodplains in the Big Creek Watershed change as the area becomes more developed. A two-dimensional hydrodynamic model of the region was created in order to map the floodplains under current conditions and projected 2045 conditions. The model was calibrated using radar rainfall from storms occurring in May 2015, August 2017 (Hurricane Harvey), and May 2019, which each caused substantial peak discharges within the watershed. The validated model was used to create floodplain maps for 10-year, 25-year, 50-year, and 100-year design storms in both current and future land use scenarios. The modeled results demonstrated that urbanization increases the peak flows within the watershed, yet urbanization was not found to change the floodplain extent a notable amount (less than 5%). This work provides data and floodplain maps that demonstrate the effects of urbanization in the area and encourage officials to deter development in hazardous areas and mitigate flood risk for the community.