Assessment of Future Coast Land Loss Along the Upper Texas Gulf Coast to the Year 2050

Abstract

Tidal gauge data from stations along the Texas Gulf Coast document high long-term rates of relative sea-level rise. Shoreline retreat and loss of coastal land in Texas have also been documented, and attributed to a combination of erosion and submergence. Submergence is caused by relative sea-level (RSL) rise: a combination of eustatic sea-level (ESL) rise and subsidence caused both by man9s withdrawal of pore fluids and natural consolidation. The Texas coastline is regressing at present and will continue into the future. We anticipate future accelerated loss of land in response to accelerated sea-level rise. Three scenarios (baseline, low-rise, and high-rise) for shoreline retreat and resulting loss of land to the year 2050 are developed for the Upper Texas Gulf Coast, north of Galveston Bay. The scenarios integrate projections of future RSL rise with empirical relations between RSL rise and shoreline retreat over a historical baseline period. The projections of future RSL rise combine estimates of eustatic sea-level rise derived from a delphic analysis with an assumed constant rate of land-surface subsidence. RSL rises of 0.49 m, 0.63 m, and 1.87 m are computed for the year 2050 in the baseline, low-rise, and high-rise scenarios, respectively. These rises correspond to losses of land of 17.1 km 2 (4,224 acres), 22.4 km 2 (5,533 acres), and 68.5 km 2 (16,920 acres) within the study area. Although the loss of land varies considerably throughout the study area, shoreline retreats of up to 1.85 km by 2050 are predicted in the worst-case (high-rise) scenario. Our assessment indicates that the Upper Texas Coast will experience significant loss of land in the future. Although this analysis contains much uncertainty, we believe it provides useful projections that should influence the future development and use of coastal resources. Such projections should be considered in geotechnical analysis, site investigations, and land-use planning.