UGA to Measure State’s Agricultural Water Use

Nobody knows how much water Georgia farmers pumped into their
fields over the dry
summer of ’99 — or, for that matter, over any summer.

“We can make some educated guesses,” said State
Geologist Bill McLemore of
the Georgia Geologic Survey, a branch of the Environmental
Protection Division of the
state Department of Natural Resources. “But there’s no
question that’s the weak spot
in our water use information system.”

With demands on water resources mounting, it’s a weakness the
state can’t afford to
carry into the next millennium. So the DNR is funding a
University of Georgia project
called Ag Water PUMPING (Potential Use and Management Program in
Georgia).

Agricultural Water Use High

Industries and cities meter their water use, McLemore said.
That allows for fairly
accurate accounting. Farmers, though, don’t keep track of the
water they use.

The DNR figures its nearly 20,000 agricultural water use
permits closely reflect the
number of irrigation systems out there.

“Agriculture is the second-largest user of water statewide,”
McLemore said. “It’s the single largest user of groundwater.”

Farmers water during the growing season. For their biggest
crops, that’s about six
months. “For that period, they may be the biggest water user
overall,” he said.
“Some big farms use as much water as medium-size
cities.”

Ag Water PUMPING

The need to measure ag water use was clear by the mid-’90s,
McLemore said. So the state
asked the UGA College of Agricultural and Environmental Sciences
to devise a project to
monitor a statistical sample of the irrigation systems.

“The U.S. Geological Survey had tried to get farmers to
volunteer in a project
like this,” he said. But the USGS approach didn’t get the
needed data. “USGS has
good planners in Atlanta. But doesn’t have a local presence close
to the farmers.”

The CAES, through its Extension Service, does. Agents in every
county work daily with
farmers and have close links with CAES engineers and other
scientists.

Monitoring 400-plus Irrigation
Systems

“We put together a proposal to measure 400-plus systems
across the state over five
years and develop (computer) models to accurately estimate total
water use,” said UGA
engineer Dan Thomas.

Thomas, a CAES professor of biological and agricultural
engineering, heads a UGA team
that began setting up the monitoring system this summer.

Using the state permits, the team came up with a sample of
irrigation systems to
monitor. They work through county agents to contact each farmer
on the list.

Farmers Take Part Voluntarily

To include an irrigation system in the study, UGA engineers
and technicians first check
its water flow rate. If the rig doesn’t already have an hour
meter, the team installs one.
Then technicians will check the meter monthly to see how long it
pumped.

The project still requires farmers to volunteer. But so far,
that hasn’t been a
problem. “Most of our farmers understand the need for this
study,” said David
Curry, an Extension agent in Toombs County.

Thomas said getting the monitoring part of the project in
place will take two years.
“About 170 systems are completed now,” he said.
“We have three groups, and
at times four, doing the installation.”

Southwest, Southeast Areas
First

Water disputes in southwest Georgia and saltwater intrusion in
groundwater along the
coast make water-use data from those areas more critical. They
were the first areas to be
included, Thomas said.

The work will soon expand. In 2000, the team will not only put
in the rest of the
monitoring sites, but will start checking the ones already
installed.

As the data begins to flow, the work on the computer models
will grow. The models will
provide accurate water-use data on many levels — by county,
drainage basin, etc.

“Statewide, we’ve got pretty reasonable water-use
estimates now,” he said.
“This will give us more precise data in local
areas.”

That data, McLemore said, is essential. “Natural resource
management is based on
good science and good engineering,” he said. “And those
depend on accurate
numbers.”

For more information on the project, contact Thomas or
research coordinator Cathy
Myers-Roche at (912) 386-3377 or agricultural engineer Kerry
Harrison at (912) 386-3442.