ERDC/CHL CHETN-II-44
September 2001
that would not be considered in the original sense, but which would substantially control the cost
of a maintenance of a beach fill or expected life of material placed on the beach as least-cost
dredged material disposal. The existence of EHSs can lead to public concern even if the overall
project is functioning properly, adding motivation to account for EHSs in initial design to assure
more uniform project performance.
Typically, but not always, an EHS persists over a time interval of an engineering project or
ownership of private property. The duration depends on the cause and is one of the classification
criteria applied to EHS as discussed in the following paragraphs.
The reader is referred to Stauble (1994), Bridges (1995), Raichle, Elsworth, and Bodge (1998),
Bodge, Gravens, and Srinivas (1999), Dean, Liotta, and Simn (1999), Liotta (1999), and Weber
(2000) for additional information and viewpoints, case studies, and direction to other
publications. Also, the concept of erosion cold spot (ECS) areas, which are anomalous
accumulations of beach material or advance of the shoreline as compared to adjacent beaches or
expected by experience, is not discussed in detail here (see, e.g., Stauble 1994; Smith and
Ebersole 1997; Dean, Liotta, and Simn 1999). Depending on the cause of the EHS, the
redistribution of the eroded material may create or preserve one or more ECSs.
This CHETN identifies and classifies all known types of EHSs and points to possible underlying
causes as presently understood. EHSs can be prevented in many situations or predicted in others,
allowing preventive or mitigation measures to be incorporated in design. In some cases,
knowledge of the temporary or periodic appearance of an EHS might be sufficient to accept the
phenomenon without remedial measures. EHS types requiring investigation to achieve
quantitative predictive capability for EHSs are identified.
CLASSIFICATION OF HOT SPOTS: EHSs can be classified by general properties, such as:
a. Duration of existence;
b. Lateral extent;
c. Processes responsible for the erosion;
d. Predominant erosion mechanism as longshore or cross-shore transport;
e. Whether the type of EHS can be predicted or remedied.
These properties are considered here for EHSs already identified in the literature and for other
EHSs presented in this CHETN. Table 1 lists all known types of EHSs and the leading causes.
Bridges (1995) compiled the first eight types in Table 1, subsequently expanded to 12 types by
Dean, Liotta, and Simn (1999). However, EHS type 7, "headlands and encroachments" can be
modified to encompass three subtypes, after Bodge, Gravens, and Srinivas (1999). These first
two-cited publications refer to sources where some of the types and causes were first reported.
Table 1 is not in order of possible frequency of occurrence or of severity, and it was prepared to
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