ERDC/CHL CHETN-II-44
September 2001
Beach Erosional Hot Spots: Types,
Causes, and Solutions
by Nicholas C. Kraus and Francis A. Galgano
types, causes, and example solutions of erosional hot spots (EHSs; singular EHS) by which they
can be identified and measures that can be taken to prevent or cope with the erosion in an
effective way. An EHS is an area with high erosion rate as compared to the adjacent beach or to
expectations for the behavior of the beach. EHSs located adjacent to inlets can compromise
beach nourishment performance or performance of the site as a placement area for beach-quality
dredged material. Possible types of EHSs are extended to cover geologic or regional scales.
BACKGROUND: Wide awareness and systematic study of EHS areas began in the 1990s with
experience gained in long-term maintenance of large beach fills at many sites (Stauble and Kraus
1993), comprehensive beach-monitoring programs, and efforts to minimize costs while
maintaining project design specifications. An EHS is an area that experiences sediment transport
potential without having adequate sediment supply. EHSs erode more rapidly than the adjacent
beaches or more rapidly than anticipated during design. EHSs can be quantitatively and
qualitatively defined by several metrics. Examples are loss of beach width (recession rate), loss
of sediment volume (erosion rate), percentage of fill remaining of the amount placed, and
perception of how a fill should perform relative to adjacent beaches or to historic rates (e.g.,
Stauble 1994; Raichle, Elsworth, and Bodge 1998).
Some coasts to be nourished are sediment deficient, obscuring the presence of latent EHSs that
emerge once material is in place. In these situations, designers must be alert to conditions with
potential of producing EHSs and account for them. The causes of EHSs need to be identified to
determine the most appropriate action for placement.
The original definition of an EHS (e.g., Bridges 1995; Dean, Liotta, and Simn 1999) was
intended to cover erosional phenomena that were unanticipated and primarily local (e.g., a well-
identified area located within a beach fill). However, in the relatively short time of several years,
the generating mechanisms or causes of most types of EHSs have been identified. Also, long
beach fills are being constructed and considered, indicating that the definition should encompass
regional extent as well as local and isolated areas.
Knowledge of coastal processes appears adequate to understand or predict the occurrence of
most types of EHSs and to formulate appropriate actions, which could range from acceptance of
the erosion to complete arresting of the erosion over the time scale of the project. Because EHSs
drive the performance of placed material, and because planning strategies should account for
areas with high erosion rates, here the definition of EHSs is extended or generalized to
encompass any area with a high erosion rate, as judged by comparison to rates at adjacent or
similar beaches. Eliminating the requirements of an unanticipated problem and/or a localized
area adds several EHS types. A prominent example is erosion on the downdrift side of a jetty,
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