58 Potato Grower | NOVEMBER 2014
diggin' in IRRIGATION Industry Report
Some Pretty Deep Stuff
New tool eases task of simulating aquifer refill
HOW QUICKLY A LAKE fills
after water is drawn for irrigation
or drinking is easily measured, but
that's not true for underground water
reserves, called aquifers. Because it
takes place belowground, groundwater
replenishment—or recharge—can't be
directly observed. Scientists must estimate
it, often by using complex mathematical
models.
A new screening tool may now ease the
task. Writing in the Vadose Zone Journal,
scientists describe a method for identifying
timeframes and regions where the seepage
of water into an aquifer is likely constant,
rather than fluctuating with rainfall
patterns or climate. By locating these areas
up front and excluding them, modelers
can then focus their computational
might where it's truly needed, says Jesse
Dickinson, a U.S. Geological Survey
scientist who led the research.
"There are a lot of complicated
processes that go on between the land and
the aquifer, and many models now include
features that can simulate variability
in infiltration from the land surface
to the water table," he says. But these
models also require much more data and
computing time, and can add unnecessary
complexity, he adds. "So what we did was
create a mathematical tool so that you can
find certain areas where maybe all that
[detail] isn't needed."
Hydrologists are adding more detailed
data to groundwater models today for
several reasons, Dickinson explains. For
one, aquifers once contained so much
water that whatever happened short-term
at the surface made little difference to
the volume stored belowground. But as
aquifers are increasingly tapped—and, in
