Computer models expected to show possible solutions to Colorado River
problems
GALVESTON -- The first presentation of model results for the Mouth of
the Colorado River Project of the Engineering Research and Development
Center Coastal Hydraulics Laboratory's models for the Mouth of the
Colorado project was held last week at a meeting in Bay City. In
attendance with the U .S. Army Corps of Engineers were representatives
from several resource agencies and the Lower Colorado River Authority.
Dr. Nick Kraus and Gary Brown, both from the Corps'
Engineering Research and Development Center Coastal Hydraulics Laboratory,
are working on separate models for separate studies to produce information
on currents, salinity, and sedimentation in the area of the mouth of the
Colorado River and around the locks and by-pass channel.
Kraus, whose model showed animations of currents at the
Mouth of the Colorado, said it is costing too much to keep the channel
there open. From 400,000 to 600,000 cubic yards of material are dredged
from the channel each year, he said. His animations showed significant
changes in currents with the opening of either Parkers Cut, or the
Southwest Cut, or with the opening of both cuts. But, if you tinker with
one place, other places are going to know it, he stated.
With the computer model of this area ready to provide
the Corps with information on a variety of different scenarios, the study
is proceeding rapidly and results should be available within a short time.
The models are regional, Kraus emphasized, and each will provide
information that will be linked in the problem solving process. The second
model, being developed by Gary Brown, relates to the area around the
comprehensive modeling for navigational improvements at the Colorado River
Locks and environmental impacts on Matagorda Bay.
When the Mouth of the Colorado Project was completed by
the Corps in the early nineties, a bypass channel was cut and Parkers Cut
was closed. Coordinated agreement on these actions was reached with the
resource agencies who were heavily in favor of closing Parkers Cut. The
intent was that the fresh water from the river would then empty into West
Matagorda Bay and help restore the bay system.
This is working as planned, says Mike Bragg, project
manager for the Corps. The marshes are developing well but not enough time
has passed to evaluate the fisheries.
Concerns about the project include differences in
opinions on the improvement of the fishing and the inconvenience causes by
having to go around and through the locks for fishermen to reach the Bay.
More sand than predicted is accumulating at the mouth
of the river. Not all the sand is settling into the sediment basin and
instead is dropping out in the channel. This causes the excessive dredging
which is necessary to keep the channel open. Dredges are working there
about every nine months, nearly twice as often as was anticipated.
Kraus has a list of nine possible actions which would
help solve this problem. They range from raising the height of the
landward weir to placing the dredged material further down the coast to
moving the sediment basin and even to the extreme of building a new jetty
if nothing else works. These are some of the scenarios which will be run
through the models. A three foot per second flow is needed to scour the
sands and reduce dredging requirements at the mouth, he said.
The more inland model being developed by Brown will
soon model the hydrodynamics of opening both the Southwest Cut and Parkers
Cut along with other scenarios to help reduce currents at the crossing of
the Gulf Intracoastal Waterway and the Colorado River. Effects to the
ecology of Matagorda Bay will be considered in determining a final
solution.
Both studies are designed to help the Corps of
Engineers determine, through the best use of science, solutions that will
bring the most benefits to both navigation and the environment.
Once the studies are completed, public meetings will be held to gather
input and comments from the public on any proposed changes to the project.
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