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Saving North America's
Greatest Aquifer by Fax
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The "Water Smart" column that appears
daily in the Amarillo Globe News provides urban lawn watering
guides based on data from the North Plains Evapotranspiration
Network. The network also faxes data to farmers to advise them
of when and how much to water.
(K9158-1)
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The Ogallala Aquifer—the largest
underground water supply in North America—still has plenty of groundwater
to pump for irrigation, despite dire predictions that it would run dry by now.
In fact, the Texas Panhandle, which is over the shallowest part of the aquifer,
has a plan in place to extend its useful life through at least mid-century,
according to agricultural engineer Thomas H. Marek, of the Texas Agricultural
Experiment Station (TAES) in Amarillo. "It's important to do this because
irrigation is the lifeblood of the Panhandle area."
Underpinning this plan is the North Plains Evapotranspiration (NP ET) Network,
built by a team of seven scientists—including Marek—from three
agencies. |
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Agricultural engineers Terry Howell (left) and
Thomas Marek maintain a weather station at the ARS Bushland experimental
North Plains Evapotranspiration Network.
(K9157-1)
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Evapotranspiration is the technical
term for all water either used by plants or lost through evaporation, explains
team member Terry A. Howell, an Agricultural
Research Service agricultural engineer in Bushland, Texas.
For information about how plant growth and water use relate to weather
conditions, the network relies on 10 years of ARS crop water-use data collected
in Bushland, Howell says.
"The NP ET network allows accurate estimates, crop by crop, county by
county, of present-day water use by farmers," says John M. Sweeten, TAES
resident director.
"Irrigation pumps aren't metered, so agricultural use predictions can be
based only on irrigation survey data and plant water-use data," says L.
Leon New, extension irrigation engineer with the Texas Agricultural Extension
Service in Amarillo. "The network helps farmers save water by advising
them of the best time to start watering, and in what amounts, and when to stop
watering—based on knowledge of crop water needs and local
conditions." |
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Research associate Don Dusek, an ARS collaborator
with the Texas Agricultural Experiment Station at Amarillo, observes
a graph of data from weather stations.
(K9156-2)
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Last year, the network sent more
than 300 fax alerts a night. Subscribing farmers saved an estimated 20 billion
gallons of precious Ogallala Aquifer water and lowered irrigation pumping costs
by an estimated $5 million a year—while raising or maintaining yields.
The Ogallala is a giant sponge of sand and gravel soaked with rainwater and
snowmelt, stored mostly when the eastern portion of the Rocky Mountains eroded
more than a million years ago. It underlies most of the Great Plains states.
The Ogallala's predicted decline has been cut by a third recently, in part
because of the network of weather stations, according to Howell.
"Some of this is simply a correction because of better data and numbers
from the network, and the rest is because of less land being irrigated and more
efficient irrigation systems available now, coupled with the fax alerts,"
says Howell.
Maintaining the network's 1,500-mile circuit of weather stations 7 days a week,
24 hours a day, is a daunting task. The network maintains two stations in
reserve in case it has to close one or two stations for repairs. The team
devised a computer program that checks incoming data to spot errors that might
result from faulty equipment. One team member comes in early each morning to
make a visual check of the data through computer-generated graphs. If repairs
are needed, a team member has to drive immediately to the station where
equipment has failed.
Texas' North Plains Underground Water Conservation District recently used
weather-station data, crop water-use data, and other information, such as
county-irrigated acreage and irrigation surveys, to predict Ogallala water
depletion with near 100 percent accuracy when measured against actual
depletion. "We could never predict that accurately with the old method,
which involved many judgment calls—and little data," Sweeten says.
The North Plains network was formed in 1994, supplementing a 1992 network that
covers the Southern Texas High Plains. In 1995, Guy Fipps, at Texas A&M
University, College Station, set up Texaset, a network that covers the north
central and southern parts of the state. ARS worked with Texas A&M
University in College Station, Texas Tech University in Lubbock, TAES, the
Texas Agricultural Extension Service, and others to develop the network.
Howell has compiled 10 years of data on crop water use gleaned from four of the
few "weighing lysimeters" existing in the world. These lysimeters are
giant pieces of farm fields, each balancing on an underground scale that
measures any weight change from water added or lost.
Many crops are grown in the lysimeters, including corn, soybeans, wheat,
cotton, sorghum, and tall fescue grass. A local school district uses the faxed
data for grass to save on its lawn watering.
"That's what we hope to see more of," Sweeten says, referring to
urban users. He wants to see the NP ET network spread not only throughout North
Plains farms, but also in towns and cities like Amarillo, Lubbock, and Dallas.
What the NP ET has done for the Ogallala Aquifer, its principles can do for
urban, as well as rural, water users anywhere. "Urbanites would do well to
study the water conservation principles developed by the Terry Howells and Tom
Mareks of the world," says Sweeten.
Sweeten, Howell, New, and Marek want to get the word out to more farmers in the
North Plains. The Amarillo Globe News publishes the crop water-needs
advisories daily. Local Amarillo radio and TV stations also report the
evapotranspiration rate data. The NP ET and many other networks are available
on the World Wide Web. The networks have "robot programs" that
automatically capture data from other networks and store it on their web sites.
Howell recently worked with colleagues to update and publish a list of all
these networks at the Irrigation Association's ET Connection at
http://www.irrigation.org.
The NP ET network doesn't provide storm warnings, but it will do about
everything else, including giving pest alerts. In fact, the summer of 2000 was
the first time farmers and consultants woke up to corn rootworm alerts faxed
from the network, giving advance notice to get ready to spray because an
outbreak was imminent.
The Texas legislature recently approved the purchase of numerous field weather
stations to create the densest such network in Texas to date. It's modeled
after Oklahoma's Mesonet, which has provided statewide coverage, including
storm warnings, since 1995.
Texas Senate Bill 1 requires the establishment of regional water plans
throughout the state for implementation on January 5, 2001. These plans will be
incorporated into an update of the statewide water plan in January 2002. The NP
ET network is identified as one of the recommended water-management strategies.
Also, the Panhandle Regional Water Planning Group is using network data to
forecast irrigation needs for the next 10 to 50 years.
The Panhandle group's goal is to make sure the wells dug into the Ogallala
after the intense drought of the mid-1950s don't run dry.—By
Don Comis,
Agricultural Research Service Information Staff.
This research is part of Water Quality and Management, an ARS National
Program (#201) described on the World Wide Web at
http://www.nps.ars.usda.gov.
Terry A. Howell is with the USDA-ARS
Conservation and Production Research
Laboratory, P.O. Drawer 10, Bushland, TX 79012-0010; phone (806) 356-5746,
fax (806) 356-5750.
John M. Sweeten,
Thomas H. Marek, and
L. Leon New are at the
Texas A&M
Agricultural Research and Extension Center, 6500 Amarillo Blvd. West,
Amarillo, TX 79106; phone (806) 359-5401, fax (806) 358-9718. |
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"Saving North America's Greatest Aquifer by
Fax" was published in the
December 2000
issue of Agricultural Research magazine.
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