Title: FEMA Partners with Oceanweather and Scripps Institution of Oceanography to Bring Modeling
Expertise to CCAMP OPC Study
Author: Justin Vandever, P.E., Coastal Engineer, BakerAECOM
Summary: FEMA brought together two key partners, Oceanweather Inc. and Scripps Institution of
Oceanography, to provide deepwater and nearshore wave modeling expertise for the California Coastal
Analysis and Mapping Project (CCAMP) Open Pacific Coast (OPC) Study. In collaboration with FEMA’s
study contractor, BakerAECOM, the study team is producing a 50-year hindcast of wave climatology for
the entire California coastline – the most comprehensive dataset of its kind ever created for a west coast
flood study. -continue readingArticle: The study process for a coastal flood study along the California Pacific coast starts many
hundreds or thousands of miles offshore in the vast Pacific Ocean basin. Waves that run up on our
beaches, causing inundation or erosion, can be generated by stormy conditions as far away as the Gulf
of Alaska, New Zealand, or close to home by strong winds blowing over the ocean’s surface. In order to
predict coastal flooding and erosion processes at the shoreline, we must first develop an understanding
of how waves are generated, travel, and transform as they move across the ocean and into nearshore
areas.
As part of the California Coastal Analysis and Mapping Project (CCAMP) Ocean Pacific Coast (OPC) Study,
FEMA brought together two key partners, Oceanweather, Inc. (OWI) and Scripps Institution of
Oceanography (SIO), to provide deepwater and nearshore wave modeling expertise. In collaboration
with FEMA’s study contractor, BakerAECOM, the study team is producing a 50-year hindcast (1960
through 2009) of wave climatology for the entire California coastline – the most comprehensive dataset
of its kind ever created for a west coast flood study. A hindcast is a historical reconstruction of past
meteorological and oceanographic conditions based on observational data and numerical modeling of
past conditions. Oceanweather, Inc. used historical meteorological data from pressure charts,
shipboard observations, buoys, and satellite measurements to reconstruct atmospheric conditions
throughout the Pacific Ocean basin for the duration of the hindcast period. Using advanced numerical
modeling techniques, the historical wind forcing was applied to a wave generation and propagation
model to simulate a 50-year continuous record of deepwater wave conditions offshore of the California
coastline.
As waves move from deep water to shallow water, they undergo complex interactions with the seafloor
which act to transform the waves and change their characteristics. Wave energy is focused in some
areas and defocused in other areas depending on a variety of factors, including wave period and
direction, seafloor topography, and coastline exposure. Scientists and engineers typically use advanced
modeling techniques to capture this spatial variability and make wave predictions in areas where direct
buoy measurements are unavailable. Using a numerical model developed by researchers at the SIO
Coastal Data Information Program (CDIP), the study team transformed the deepwater wave conditions
from OWI’s offshore hindcast to determine the coincident wave conditions at the shoreline. Wave
model output is recorded in 10-15m water depths (at the edge of the surf zone) at a spacing of 100-
200m alongshore. The high resolution of the wave transformation model output ensures that accurate
nearshore wave data are applied to each coastal reach within the study area. Various wave parameters,
such as wave height, period, and direction, are computed and archived with the model hindcast data at
each output point for later use in wave run-up computations at the shoreline.
Additional information about OWI and SIO CDIP can be found on their websites: OWI and CDIP
Links for above text:
OWI - http://www.oceanweather.com/
CDIP - http://cdip.ucsd.edu/
[Will find a more interesting graphic for final]