1D and 2D Methods for Modeling Floodplains under Storm Surge Conditions
Bedient, Philip B.
Master of Science
This study evaluates a 1D and a 2D method for analyzing the combined effect of inland rainfall and hurricane-induced storm surge on a coastal floodplain. Horsepen Bayou near Clear Lake, southeast of Houston, Texas is vulnerable to storm surge, which can travel upstream into the Bayou and exacerbate flooding outside the designated floodplain. However, the current 100-year floodplain for this area is delineated using a 1D model without direct storm surge inputs. Additionally, floodplains with flat topography, like Horsepen, could be modeled more accurately using 2D models, instead of the traditional 1D approach. A 1D HEC-RAS model and a 2D XPSWMM model are used to compare the resulting floodplain from three historical storms and one synthetic storm. When compared to actual FEMA flood claims, the floodplains calculated by the 2D model are more representative of inundation hazard in Horsepen and therefore a better tool for evaluating flooding in the area.