EM 1110-2-1100 (Part II)
30 Apr 02
Figure II-5-24.
Hurricane Gloria track from 17 September to 2 October 1985 (Jarvinen and Gebert
1986)
(b) Three approaches are commonly used for developing site-specific frequency relationships. These
are based on: 1) historical data, 2) synthetic data, and 3) empirical simulation technique (EST) approaches.
The historical approach assumes that a database of historical storm events and their respective surge
elevations is available for the study area. It is further assumed that the available database provides a
representative sample of all possible events for that particular site. Many coastal locations do not have
adequate historical data from which frequency-of-occurrence relationships can be developed. Even if a
reasonable number of years of data are available, there is no assurance that the data represent a full population
of possible storm events. Therefore, it is usually the case that historical data are insufficient for generating
a reliable frequency-of-occurrence relationship. For this reason, synthetic or empirically based approaches
are generally preferred.
(c) The synthetic approach is based on the construction of a large number of hypothetical storm events
based on assumed probability laws dictating the intensity of the storms and their associated frequency
relationships. A more recent approach to the developing frequency-of-occurrence relationships is through
the statistical approach known as the empirical simulation technique. This approach is a resampling or
"bootstrap" scheme in which the probability relationships of a historical database are used to develop
frequency relationships.
II-5-44
Water Levels and Long Waves
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