Multi-decadal gravel berm observations in southern California

Gravel berms occur naturally on beaches worldwide, may provide defense against beach erosion and coastal flooding, and have been increasingly built around the world including the U.S. west coast. Recent studies observed longshore transport caused gravel loss from artificially built gravel berms prompting concern about their future stability. However, few observations of long-term gravel-berm behaviors and stability exist. Using historical observations since 1980s combined with modern LiDAR-based observations, this study quantitatively examines multi-decal morphological changes of natural gravel berms in southern California. The morphological observations are compared with wave conditions and local engineering coastal modifications. This contribution provides novel multi-decadal evolution of gravel berm morphology in a relatively urbanized coastal area and useful insights of long-term gravel berm behavior and stability.