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City of Solana Beach
Section 3
Shoreline and Coastal Bluff Management Strategies Draft MEIR
Environmental Impact Analyses
conclusion that both types of beaches went through the same cycle of erosion and deposition
under control of wave conditions offshore with no appreciable affect of structure. In the majority
of cases, seawalls are constructed to protect structures landward from erosion due to other
causes and, therefore, are located in areas where erosion is already occurring. As a result,
erosional features may be observed adjacent to seawalls, but they do not justify the conclusion
that seawalls cause erosion.
According to the Committee on Coastal Erosion Zone Management (CCEZM, 1990; Wiegel,
2000), properly engineered seawalls and revetments can protect the land behind them without
causing adverse effects to the fronting beaches. Proper design, construction, and maintenance
of seawalls and revetments are emphasized, for improperly constructed seawalls may, indeed,
cause adverse impacts on adjacent property. It is often for these impacts that seawalls in
general get blamed for causing erosion. At the same time, the role of seawall design (especially
the role of permeability of the wall itself) is not completely understood (Tait and Griggs, 1991)
and further studies are recommended.
Although field observations may be compared at different sites and different shorelines, and
generalized conclusions may be made, the evaluation of the impact of seawalls on beaches
remains site specific. Coastal processes in general are the same, but wave climates, beach
profile dynamics, shoreline configuration, etc. vary from site to site.
Two previously mentioned detailed studies allowed the evaluation of general and site-specific
impacts of seawalls on the Monterey Bay beaches with no long-term erosion (Griggs and
others, 1994), and on the progressively eroding beaches of the southern Atlantic Coast of
Virginia (Basco and others, 1994; Wiegel, 2000). In both studies, beach profiles at beaches
with seawalls, and at beaches without seawalls (control beaches) were periodically surveyed,
along with the other data collected. Tait and Griggs (1991) provided a very thorough overview
of the beach responses to the presence of a seawall, both observed in the field, and
hypothetical (predicted, but not documented in the field), along with the processes and controls
thought to cause these responses.
It is very clear that response of the beach to the presence of a seawall is site specific and
should be studied as such. However, in the absence of detailed studies in the Solana Beach
area, some of the observations and conclusions of Griggs and others (1994) may be cautiously
utilized.
Short-term Effects
The majority of the field studies indicate that most of the direct effects of seawalls on beaches
are short term, or seasonal. The impact of seawalls on beaches is generally remedied during
the recovery phase (see Tait and Griggs, 1991, for the list of references). However, each
situation is unique, and seawall effects that proved to be seasonal at some sites, were observed
to be irreversible at the others. The following effects were observed at a variety of sites:
Project No. 323530000
Page 3-15






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