Lidar time-series analysis of a rapidly transgressing low-lying mainland barrier (Caminada Headlands, Louisiana, USA)

Abstract

Coastal barriers are the first line of defense against storm surge and wind wave induced hazards. Their response to such events, therefore, require continual assessment. Airborne lidar surveying is a valuable remote sensing technique used to assess the dynamics of coastal dunes driven by the impacts of storms and the subsequent recovery processes. Different from previous research conducted on this topic, where pre- and post-storm surveys are employed to analyze the effects of isolated extreme events, this study makes use of a 15-year lidar survey time series of the Caminada-Moreau Headlands. The Caminada-Moreau Headlands, located in Louisiana, USA, on the Gulf of Mexico's northern coast, is a low-gradient, low-elevation mainland barrier which is rapidly eroding due to sediment deprivation, alongshore sediment transport, relative sea-level rise, and cumulative storm impacts. The time period analyzed, from 1998 to 2013, was notable for the number and intensity of hurricanes and tropical storms making landfall in the region. The analyses of the lidar data show that, while storms have frequently overwashed and destroyed the dunes, natural dune recovery has managed to maintain a nearly stable alongshore-averaged dune volume. On the other hand, change in dune crest elevation in the most vulnerable stretches of the coastline has not kept pace with sea-level rise. The analyses herein further suggest that, for low-elevation dunes which rapidly transition into backbarrier wetlands, the relative quantity of subaerial land surface area to open water, directly landward of the duneline, is an influential parameter affecting barrier shoreline morphodynamics.