Geospatial model output of land cover change and storm surge impacts under projected sea level rise and category 2 hurricanes along the Texas Coast

The Texas coast is vulnerable to sea level rise and coastal flooding because it is a low-lying coastal plain with gently sloping topography and eroding coastal environments. In addition, local land surface subsidence is increasing the risk of sea level rise by enhancing the reach of storm surges and tides further inland. Furthermore, it is estimated that the population living within Texas’ 18 coastal counties will increase by 52% from 2010 to 2050, reaching 9.3 million. Given the increasing vulnerability of the Texas coast, this study assesses the impacts of sea level rise and associated enhanced storm surge to better understand the relative susceptibility to negative impacts on the natural and built environments.

This study is part of the second publication of the Texas Coastal Resiliency Master Plan (TCRMP), an ambitious coastal planning effort by the Texas General Land Office (GLO) to make the Texas coast more resilient to hazards. This study employs the Sea Level Affecting Marshes Model (SLAMM) to project the possible effects of sea level rise on coastal habitats under 1 meter of global sea level rise scenario by year 2100. The relative component of sea level rise is determined on a regional basis by deriving an average trend from long-term records of coastal tide gauges.

The coupled hydrodynamic storm surge model, Advanced CIRCulation (ADCIRC) and Simulating Waves in the Nearshore (SWAN), is used to identify the threats posed by storm surge and nearshore waves to people and the ecosystem in the current and 2100 environments. Six synthetic Category 2 hurricanes making landfall near to the major bay systems or city centers across the Texas coast are modeled with ADCIRC+SWAN for both current and 2100 environments. The 2100 surface and land cover predicted by SLAMM is used as a representative of future elevations and land cover type for input to the ADCIRC+SWAN model.

Results from this study will help state, local, and federal decision makers understand the value provided by the coast, the inherent risks the coastal communities face, and the opportunities available to manage a dynamic coastal environment in a more resilient manner.