Angelina Freeman’s background in acoustics is a great
fit for research that LSU Boyd Professor Harry Roberts describes
as “one of the great new thrusts in coastal work.”
In the project that Roberts is planning for south Louisiana,
that means imaging the sea floor and bay bottoms in shallow
water environments, looking below the bay bottoms with high–resolution
acoustics, and using the resulting data to build a very
detailed geologic framework for help in understanding changes
in our coastal environment.
“We’ve never been able to do that before,”
said Roberts.
Two new developments will help get this project underway.
One is a new boat the Louisiana Department of Natural Resources
(DNR) is providing. The other is the Coypu Foundation Fellowship
that will fund Freeman’s doctoral studies and research
in SC&E’s Department of Oceanography and Coastal
Sciences (DOCS) for the next four years.
Freeman’s unique academic background and work experience
seem tailor–made for the research project that Roberts,
her major professor, has in mind. Her undergraduate degree
is in physics, and she has a master’s degree in acoustics
from Penn State and one from SC&E’s Department
of Environmental Sciences, where she worked on water quality
with Assistant Professor Conrad Lamon. Between the two master’s
degrees, she worked for close to five years, doing some
seismic and acoustic modeling. One project involved trying
to discriminate between underground explosions and earthquakes
as part of the international Comprehensive Test Ban Treaty.
In the research statement that Freeman prepared for the
Coypu Foundation fellowship application, she said that her
ultimate career goal is to contribute “to environmental
sustainability by providing scientific guidance for the
wise use of our natural coastal and oceanic resources.”
Her interest in coastal and oceanic resources began when
she was growing up in Florida. “While living within
blocks of the Gulf of Mexico, I personally experienced both
the detrimental and beneficial effects of various anthropogenic
activities on the marine and coastal environment, contributing
to my deep respect and urgent concern for marked stewardship
of our magnificent resource.”
“I’m very grateful to Coypu for the fellowship,”
said Freeman.
“We’re both very grateful to Coypu,” said
Roberts.
In Roberts, Freeman has found a major professor whose research,
spanning 36 years in DOCS’ Coastal Studies Institute
(CSI), matches her interests and career goals. Roberts has
developed a number of techniques to facilitate his coastal
research.
“We’re using a very high–resolution side
scan sonar system to look at the configuration of the ocean
bottom. It’s like taking a sonic picture of the sea
bed. And we have a profiling system that will allow us to
look beneath the sea bed to within a sediment column with
a bed resolution of about 10 cm, which is really very good.
It’s like cutting a cake and examining the layers
to help determine their origins and relationships to one
another. Using standard sedimentological and radiometric
dating techniques we can calculate rates of sediment accumulation
and rates of subsidence. The sub–bottom data will
allow us to determine how different parts of the system
are put together, and if different parts of the system are
being deformed or displaced. One of the key issues now in
looking at coastal land loss is faulting.
“Part of the theme of Freeman’s Ph.D. work will
be to evaluate whether faults are actually active and adding
to the coastal land loss problem. If they are active, she’ll
try to quantify their activity, frequency of faulting events,
and amount of vertical displacement.
“We now have the tools to do all these things,”
said Roberts, “and put together a really coherent
and accurate story of the geologic evolution of our coastal
bays. They weren’t always bays. They were part of
the coastal plain, and then they developed into bays. We
want to understand that process, how fast it happened, and
what the processes were that forced the landscape evolution.
“There are many different indicators that faulting
may be a process to look at in coastal erosion. There are
apparent offsets in the marsh, marsh lineations that apparently
are related to faulting. There are offsets in the bay bottom
that could be related to faults.
“Whether these faults are deep–seated and really
have a lot to do with our land loss problem, or whether
they simply reflect adjustments related to differential
compaction over different kinds of sediment bodies, we don’t
know. These are questions that we hope to answer,”
said Roberts.
Freeman’s project is part of a long–term effort
that is now being recognized and funded by the state. One
of the impediments to doing this type of work has been that
most standard survey vessels draw about six to seven ft
of water and Louisiana’s bays are around five–ft
deep.
To overcome that problem, “DNR is funding the construction
of the first shallow water survey vessel ever made specifically
for south Louisiana water,” said Roberts. “It
is under construction right now and will be finished by
January or February. We hope to be online by summer 2005.”
The vessel is a Lafitte skiff hull design modified for doing
survey work in shallow water. It will be 41–1/2 ft
long and 16–1/2 ft wide with tunnel drive, which means
the propellers are pulled up into a tunnel in the hull,
allowing the vessel to operate in water depths as shallow
as two ft. The boat will have an A-frame for deploying equipment
for taking sediment cores and collecting samples. Side–scan
sonar equipment will be towed from the bowsprit. The boat
can be used offshore as well as in bays, so it will be useful
for survey and sampling work on the inner shelf, particularly
related to identifying sand resources for barrier island
reconstruction, a vital component of the coastal restoration
effort.
“We’re very fortunate that DNR is providing
this boat. Having this capability is really important to
the state,” said Roberts. “I think part of the
reason we got the boat is that our group, the Coastal Studies
Institute (CSI), has very talented people who can maintain
it as well as its scientific instrumentation. We also have
two licensed captains now in our field support group at
CSI.”
The vessel will play a big role in Freeman’s research.
“We’ve worked very directly with the Louisiana
Department of Wildlife and Fisheries and DNR on evaluating
oyster beds leases for the state, projects that have involved
CSI, Coastal Fisheries Institute, and Sea Grant personnel,”
said Roberts. “But, I think the work Angelina will
be doing will extend beyond the oyster evaluation problem.
We want to actually learn more about evolution of the bays
and do a better job of calibrating the acoustic data to
real world bay bottom conditions. I think that the datasets
that we collect to answer certain specific questions, such
as the faulting question, will serve as baseline data for
a lot of other studies. For example, data collected in Barataria
Bay or Terrebonne Bay will include bathymetry [relief on
the bay floor]. Bathymetry can be used for many kinds of
modeling related to the bays. It’s very critical to
get good bathymetry as a boundary condition for numerical
models.”
Although the goal will be to eventually survey the whole
Louisiana coast, accomplishing that could take 10 years.
Roberts and Freeman will cover the most critical areas first,
working in conjunction with the DNR.
“DNR recognizes the need to collect data in preparation
for large–scale diversions, for example,” said
Roberts. “Currently, we don’t have adequate
baseline data from our coastal bays. Judging the success
or failure of river diversions, for example, will depend
on having good baseline data from impacted areas. The databases
we plan to collect will serve as a baseline for evaluating
those types of restoration projects.”
Once the data are collected, Freeman’s expertise will
come into play. “Angelina has the background,”
said Roberts, “to take, for example, the acoustic
side scan data and compare the reflectance values to sediment
properties. Her research may provide the opportunity to
actually create a system that will allow us to predict the
character of our bay bottoms from the acoustic data.”
Freeman has a full year of class work ahead of her and will
get started on data collection for her project next summer.
Between now and then she will learn new computer programs
and data processing techniques so that when she gets the
datasets she’ll be able to step right in and start
to process them.
“Angelina’s background is unique,” said
Roberts, “and that provides a unique opportunity for
us to have an acoustics person work on our coastal problems.
She’s really a good fit, and I think the end product
of her work is going to be something very useful to the
state.”
