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 Solana Beach Coastal Preservation Association
August 20, 1998
Project No. 1831
Page 12
We have also reproduced on Figure 6 a typical offshore profile off of La Jolla, reported by
Inman and Bagnold in 1963, illustrating the seaward sloping shore platform in this area,
overlain by upwards of 10 feet of sand, having a fairly wide summer backshore. As
indicated in the Corps sand thickness survey report (USCOE, 1988), variable-thickness
offshore sand deposits exist, extending well beyond the depths of their survey out to the -30
foot contour.
3
EXISTING COASTAL PROCESS ENVIRONMENT
3.1
Wave Climate
The wave climate controls coastal erosion and considerable hindcast data is available to
assess future conditions. Accordingly, it is feasible to establish geotechnical and structural
design criteria for coastal structures based on the wave climate and, hence, future erosion
that may affect a structure during its useful design life.
Waves along the San Diego County shoreline generally range in height from 2 to 5 feet;
however, large waves ranging from 6 to 10 feet in height are not uncommon. These large
waves, which can arrive at almost any time during the year and may continue for 3 to 4
days, are frequently unaccompanied by strong winds. Breakers with estimated heights of
15 to 20 feet have been observed off the coastline within the study area (USCOE, 1960;
National Marine Consultants, Inc., 1960; USCOE, 1991). The recommended 100-year
shallow-water design wave for the study area is 19.4 feet (USCOE, 1991).
This section of coastline is exposed to wave action, undiminished by island interference,
through only two relatively narrow corridors of wave approach. Waves with periods longer
than 10 seconds approach the shore from the northwest between Santa Rosa Island and
San Nicolas Island, and from the southwest between Cortez Bank and Los Coronados
Islands. The longer-period waves approaching from other directions are obstructed by the
various channel islands, Tanner Bank and Cortez Bank, and the Los Coronados Islands.
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