June 13, 1997
EXPERIMENT STATION, FORT HOOD GO TO WAR WITH SEDIMENT
Writer: Steve Hill, (409) 845-6717, [email protected]
Contact: June Wolfe, III, (254) 770-6672, [email protected]; Dr. Dennis Hoffman, (254) 770-6562, [email protected]; Don Jones, (254) 287-1090, [email protected]
TEMPLE -- Tanks may be destructive by nature, but with the help of the Texas Agricultural Experiment Station, the U.S. Department of Defense is trying to make them more environmentally benign.
A water-quality monitoring project at Fort Hood, the huge Central Texas base where armored vehicles roam the landscape, is helping determine how soil erosion may be impacted by military training exercises. The information will be used to reduce environmental impacts, project coordinators say.
While national defense won't take a back seat to efforts to keep soil in place, the Army will use the study to determine if "best management practices" for reducing erosion and sedimentation in streams are working, said Don Jones, a civilian soil conservationist for the Department of Defense at Fort Hood.
"Monitoring the water quality is part of the overall resource management scheme," Jones said. "It helps evaluate our practices and indicates sediment sources."
By comparing sediment in stream flows at various sites, they should be able to tell whether various approaches to reducing erosion are working.
Among those are establishing special grass "filter strips" near stream beds to reduce sedimentation. Others include building special "sediment traps" that are modified stock ponds for gathering runoff, reshaping and filling gullies, dedicating roadways for vehicle use, and revegetating with both native and introduced grasses and forbs.
Many of the practices started in 1995, about the same time Jones began planning the water-monitoring project with Dr. Dennis Hoffman, an experiment station research scientist at the Blackland Research Center in Temple. By mid-1996, Hoffman and several colleagues had monitoring stations in place, and they currently are collecting data and refining their monitoring techniques.
The project team now has 10 stations located in waterways at various points on the 340-square-mile reservation, which is part of the Leon River watershed in Bell and Coryell counties. Three more stations are planned.
When rain water reaches a certain level at each station, a computer-driven mechanism located in a protective case on the streambank draws water through tubes into a sampling apparatus housed in the case.
Water levels are converted to flow estimates using a specially developed equation for each site. Up to 24 samples are taken on a timed basis at each site, and each is then measured for sedimentation in the Blackland Research Center's Water Quality Laboratory.
"There is some trial and error involved with both equipment and our monitoring," said June Wolfe, III, project manager for the effort. "We're replacing some of our original equipment with bubblers that measure water depth by measuring the force needed to get bubbles through a tube, and we're trying to improve our water-velocity measurement to get better baseline flow rates."
Wolfe or another Blackland employee goes out every time it rains and collects samples from each station. "It's a 140-mile round trip," he said.
"We also go out at least once a week for routine maintenance. We make sure the batteries are charged, nothing is clogged, and no cows have eaten through the sampler housing on the solar panels, among other things."
There have been vandals at one site and a worm clogging a water tube, but for the most part, the system has worked well. It kicks in whenever water rises above a certain level in the creeks, measuring stream flow every five minutes and pumping a sample every hour until all 24 bottles in each station are filled or the water level falls.
Other project objectives are to develop a water quality data base for Fort Hood, which is a significant component of the Leon River watershed, and to evaluate best management practices over the long term by using a specialized computer model for assessing water supplies and nonpoint source pollution on Fort Hood.
The model, called the Soil-Water Analysis Tool or SWAT, helps resource managers assess supplies, soil erosion, and water and sediment transfers through complex watersheds. It was developed at the Blackland Center and has been used for many other water projects.
"We'll use the data to calibrate the model for specific predictions at Fort Hood," Wolfe said. "We may not get definitive answers on how much sediment is in a watershed, but with consistent measurements, we'll get a relatively good grasp on whether it's getting worse or better."
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