Beach Erosion Hot Spots

Beaches that exhibit anomalously high erosion rates, relative to the surrounding beach are defined as erosional hotspots. The cause of the accelerated erosion, while of research interest, has significant practical application as well. Corps project design methods typically assume constant or gradually varying alongshore response. However many projects exhibit spatially uneven behavior at different times in their life cycle and erosional hotspots located within project areas can lead to shorter project life and/or higher maintenance costs. Detecting uneven project responses in their early stages, characterizing them as persistent or temporary, and estimating their evolution is the topic for a new research effort of the Coastal & Hydraulics Laboratory (CHL).On the Outer Banks, NC, erosional hotspots pose a threat to private homeowners.

The literature provides many examples of hotspots (see Kraus and Galgano, 2001; Dean et al., 1999) but the scope of the problem in both number of hotspot occurrences around the US and their causes remains speculative. The ability to mitigate these erosional hotspots requires effective low-cost monitoring techniques and simple diagnostic methods that can link underlying geology, response time histories, changes in beach and nearshore morphology, and other non-traditional factors to the knowledge and information developed during project design and gathered by conventional monitoring.

A first step in developing hotspot mitigation guidance is to identify and classify known hotspots. This hotspot knowledgebase will serve several purposes including: 1)quantify the occurrence of hotspots, 2) provide preliminary guidance to Corps engineers based on experience gained from known hotspots, and 3) provide a classification system and database from which to identify candidate cases for further study on the causative processes. The development of the database is a cooperative effort between CHL and the Virginia Institute of Marine Science (VIMS).