Annual to Decadal Morphodynamics of the Beach-Foredune System along the Texas Upper Coast

Abstract

It has been documented that the Gulf of Mexico shoreline along the Texas upper coast is eroding at an average rate of 1.6 m/yr. (Paine et al., 2011). Relative sea-level rise, local circulation patterns, high intensity storms and lack of sediment supply combined with anthropogenic activities along developed areas of the barrier island may have contributed to this chronic erosion, although the relative significance of each is still largely unknown. Barrier island transgression takes place as a result of both ongoing alongshore and onshore sand transport by waves through hydrodynamic processes and transport into the dune system through aerodynamic processes, as well as by episodic events associated with, for example, the impact of hurricanes. The purpose of this study was to quantify the amount of sediment accretion/erosion at various locations within the beach-foredune system along the Texas upper coast to measure consequent changes in beach-foredune morphology. This was done for periods ranging from a few days to multiple years using topographic profiles, aerial photography, and lidar data. The data collected was used to determine the significance of the relationship between observed temporal/spatial patterns of morphological change with the following controlling variables: shoreline position, vegetation line, beach width, foredune crest/toe line, and dune stoss slope geometry. The relative significance of seasonal/annual processes verses response of the foredune system to broader geomorphic controls (e.g., relative sea level rise, storms, etc.) will also be assessed.