Coastal Texas Protection and Restoration Feasibility Study : Coastal Texas flood risk assessment : hydrodynamic response and beach morphology

Abstract

The US Army Corps of Engineers, Galveston District, is executing the Coastal Texas Protection and Restoration Feasibility Study coastal storm risk management (CSRM) project for the region. The project is currently in the feasibility phase. The primary goal is to develop CSRM measures that maximize national net economic development benefits. This report documents the coastal storm water level and wave hazard, including sea level rise, for a variety of flood risk management alternatives. Four beach restoration alternatives for Galveston Island and Bolivar peninsula were evaluated. Suites of synthetic tropical and historical non-tropical storms were developed and modeled. The CSTORM coupled surge-and-wave modeling system was used to accurately characterize storm circulation, water level, and wave hazards using new model meshes developed from high-resolution land and sub-aqueous surveys for with- and without-project scenarios. Beach morphology stochastic response was modeled with a Monte Carlo life-cycle simulation approach using the CSHORE morphological evolution numerical model embedded in the StormSim stochastic modeling system. Morphological and hydrodynamic response were primarily characterized with probability distributions of the number of rehabilitations and overflow.

Coastal Hazards System–Louisiana (CHS-LA)

“…As part of the CHS, the USACE initially developed a version of the JPM with a hybrid optimal sampling approach for the NACCS (Cialone et al 2015;Nadal-Caraballo et al 2015) and the CTXS 1 (Melby et al 2021). This hybrid JPM approach evolved into the PCHA framework by incorporating significant advancements that will be discussed later in this section.…”

Coastal Hazards System–Puerto Rico and US Virgin Islands (CHS-PR)

“…This study provides necessary information related to coastal storm-induced hazards to support coastal engineering and planning activities conducted by the USACE and partners. The CHS-SACS takes advantage of the CHS PCHA framework, which has been implemented in other recent USACE regional coastal studies such as the Coastal Hazards System-Louisiana (CHS-LA) study (Nadal-Caraballo et al 2022) and the Coastal Texas Protection and Restoration Study 1 (CTXS) (Melby et al 2021), leading to consistency of methodology applied and results obtained for US hurricane-exposed coastlines. The PCHA is a statistical and probabilistic framework that builds upon previous joint probability analysis methodologies while incorporating several statistical and machine-learning advancements for more robust and accurate quantification of coastal storm hazards and uncertainty.…”