Public Infrastructure

Lake Jackson, Texas


Bastrop Bayou Floodplain Mapping

Quality. LJA updated special flood hazard area mapping for Bastrop Bayou located in Lake Jackson, Texas. The floodplain mapping project provided superior mapping of flood risks in the Bastrop Bayou region in an effort to assist the City and the public in making well-informed decisions in the event of a flood event.

The LJA project team provided detailed hydraulic modeling (HEC-RAS and XPSWMM 2D) along with floodplain mapping to strict FEMA specifications. Current riverine hydraulics were the basis to update coastal surge and combined probability mapping. We managed the preparation of a two-dimensional flow model (XP-SWMM 2D) to determine complex overland flow patterns and flow distribution through TxDOT structures and channels. Additionally, we prepared inundation mapping, SFHA mapping, and HEC-RAS computer models with LiDAR-derived topography. Public outreach and education were key components of the project, and we managed the extensive coordination effort with FEMA and other stakeholders.

For more information regarding this project, please contact John Grounds, III PE, PhD, D.WRE, CFM at


Flood Control & Drainage


HEC-RAS Modeling