A Fully Probabilistic and Response-Driven Approach for the Design of Coastal Storm Risk Management Systems: A Case Study of the Sabine Pass to Galveston Bay Project

A probabilistic coastal hazard and design analysis was completed to enhance existing Coastal Storm Risk Management (CSRM) systems in Port Arthur and Freeport, Texas (TX) and construct a new CSRM system in Orange County, TX. CSRM systems in this tropical cyclone (TC)-prone region comprise earthen levees, concrete floodwalls, pump stations, and gates. A joint probabilistic model of TC parameters was developed to span the practical probability space. A suite of 195 synthetic storms was effectively sampled to represent the coastal storm surge and wave-driven flood hazard in this region. Wind and pressure fields were developed using the planetary boundary layer model and modeled in the Coastal Storm Modeling System (CSTORM) coupled circulation, water level, and wave modeling system. Existing CSRM designs and elevations, as well as with-project designs, including new reaches to the system and updated elevations to existing structures, were modeled under three relative sea level condition scenarios. Model output was used to estimate wave, water level, and coastal-structure response hazard in a fully probabilistic, response-based framework. Combined overtopping and overflow hazards were used to identify optimal CSRM system component crest elevations associated with design exceedance limit states. CSRM alignments were evaluated using a flanking analysis.