Questionnaire Results
Erosional Hotspots: An Online Characterization
The objectives of the project are 1) to quantify the occurrence of hotspots, 2) to provide preliminary guidance to Corps engineers, and 3) to provide a classification system and database from which to identify candidate cases for further study on the causative processes. Information regarding various hotspots in the US was collected from Corps Districts through an online questionnaire (http://www.vims.edu/physical/hotspot/survey.html or the "Questionnaire" link above). The data have been categorized and are presented here. You will find charts and graphs that attempt to constrain the general character exhibited by hotspots and the conditions in which they occur. Hotspot characteristics reported include the following:
- Size
- Erosion types and rates
- Wave dynamics
- Bathymetry
- Geomorphology
- Beach state
- Presence and Type of Engineering Structures
- Modeling/Mitigation Success
The data presented begin to elucidate characteristics that are common to most hotspots and to highlight those qualities that are more specific. We hope more specific characteristics will give clues to the primary mechanisms responsible for the observed hotspot behavior. It should be noted that the data are from only 6 questionnaires. We expect as more questionnaires are answered, results will become more definitive. The following figures should demonstrate what will be done with the information received and its usefulness in characterizing hotspots and the environments in which they occur.
Hotspot Size and Erosion Characteristics
Oceanographic Characteristics
Geologic Characteristics
Geologic Characteristics, continued
Nearshore Bars and Underlying Geology
Modeling and Mitigation
Other Findings: All hotspot sites had a history of beach fill, the most recent fills occurring in 2001, 2000, and 1997 at various sites. None of the sites reported rapid recovery (heightened accretion) after erosion events, suggesting that fills will have to continue if the beaches are to be preserved. In almost all cases the grain size of the beach fill was similar to or exactly the grain size of the native sediment.