Major flooding could happen again, experts warn

Major
flooding could happen again, experts warn
…………………………………………………………………

BY B.J. ALMOND
Rice News Staff

“It’s
safe to say this will happen again.”

The National
Weather Service’s Bill Read made that statement about
Tropical Storm Allison after citing local rainfall statistics
from the previous century during a conference at Rice Nov.
13.

Recalling that
Tropical Storm Claudette dumped 43 inches of rain in 24
hours and that Tropical Storm Amelia brought 46 inches over
48 hours, Read noted that rainfall exceeding 20 inches in
under 12 hours occurs fairly often in the Houston area.
Allison deluged Houston with 28.5 inches in 12 hours.

Though another
tropical storm like Allison might be inevitable, its effect
and the city’s response do not have to be the same
as they were for Allison. The conference at Rice, organized
by Phil Bedient, the Herman Brown Professor of Engineering,
for the Department of Civil and Environmental Engineering
and the Texas Medical Center, gathered a variety of experts
and storm survivors to share knowledge about and lessons
learned from Allison and its impact on Brays Bayou.

Read encouraged
more residents to consider flood insurance, because most
of the flooding caused by Allison occurred outside the 100-year
flood plain.

He also acknowledged
the need for better ways to barricade flooded roads. Of
the 22 people who died directly as a result of the flood,
10 drove their vehicles into flooded roadways and eight
walked into floodwaters.

“The message
needs to be taught that in an urban flood, you should stay
where you are,” Read said. “‘Seek higher
ground’ means go up to a second floor or to the roof
and wait for rescue. Once the water is in your house, it’s
deeper in the street than in your house.”

Below are excerpts
from some of the other speakers at the conference.

Richard Wainerdi,
president of the Texas Medical Center, said Fannin Street
accumulated 5 feet of water during the storm. Because most
of the streets around the medical center became inaccessible,
Wainerdi said plans are under way to add two bridges across
Brays Bayou — one extending Bertner Avenue to Braeswood
Boulevard and one extending Cambridge Street to MacGregor
Drive — to improve drainage along Fannin.

Roy Dodson of
Dodson and Associates Inc. advocated that advanced technologies
be used for floodplain analysis. Many flood- plain maps
are outdated and inaccurate, he said. Lasers mounted in
aircraft can measure terrain and provide digital topographic
maps with much greater accuracy.

Anthony Holder,
research scientist in environmental science and engineering
at Rice, explained how storm-water modeling can be used
to study the flooding that occurred around Harris Gully,
which runs under the Texas Medical Center. The model takes
into account four types of data: rainfall, minor drainage
systems (pipes, culverts and inlets), major overland drainage
systems (streets, open channels and storage areas) and the
tailwater conditions in the receiving stream (Brays Bayou).
The model indicates areas where flooding is likely to occur
during heavy rainfall. Altering the local drainage system
and managing the overland flow in the Texas Medical Center
(TMC) are possible solutions to mitigate the impact on Harris
Gully.

Bedient described
how the Rice/TMC Flood Alert System (FAS) provided up to
two hours’ notice to the medical center about the flood
danger posed by Allison. Bedient and colleagues developed
FAS for Brays Bayou, which rises more quickly in response
to rainfall than other bayous in the city. The system entails
computer modeling that combines topography, land use, an
advanced radar system and rain and stream gauges to track
the amount of rainfall and runoff over time. Bedient hopes
to improve FAS by incorporating variable rainfall and two-hour
weather forecasts into the system.

Carol Ellinger,
a ’91 Rice alumna who works for the Harris County Flood
Control District, presented an overview of Project Brays,
a federal plan to reduce the potential for flood damage
along Brays Bayou. This $455 million, 14-year project entails
modifying channels to move water to detention facilities
or Galveston Bay, replacing or modifying bridges, preserving
flood-prone land before it is developed for real estate
and managing regional detention basins. Ellinger expects
80 percent of the benefits to be effective by 2009.

Rice President
Malcolm Gillis also spoke at the conference, describing
how fortunate the campus was to have escaped the worst of
the storm’s impact. He encouraged the group of 140
conference attendees to convince others of the need to prepare
for another storm like Allison so they can reduce the scope
of future damage.