23, 2004, ARS News Service: Have Americans
grown used to an overabundance of rain? Scientists at
the Agricultural Research Service's Grazinglands Research
Laboratory in El Reno, Okla., think so. They want everyone
involved in water management today to prepare for normal,
drier precipitation patterns.
Soil scientist Jean Steiner warns that drier conditions
would increasingly stress water-supply systems, causing
water-usage conflicts. She adds that management strategies
that account for precipitation variations--and use the
latest technologies--should be developed.
One aspect Steiner and her colleagues--hydraulic engineer
Jurgen Garbrecht and hydrologists Michael W. Van Liew
and John X. Zhang--are focusing on is how computer-generated
seasonal forecasts and precipitation-trend data can
be tailored to help gauge long-term effects of drier
conditions on streamflow and water supplies.
Garbrecht and Schneider studied National Oceanic and
Atmospheric Administration records from 1895 to 2001
and found that precipitation over the United States
from 1971 to 2000 was about four percent higher than
during the entire period studied. It's now been drier
over the past couple of years, something the researchers
see as perhaps the start of a new trend.
One study, by Van Liew, showed how reliance on abundant
rainfall can lead to problems in drier times. When precipitation
in an Oklahoma creek was 20 percent greater than average,
streamflow increased by 39 percent; but when precipitation
was 40 percent greater than average, streamflow increased
by 96 percent.
Meanwhile, Zhang related this research directly to
agriculture by using seasonal climate forecasts and
climate-change projections to measure the effects of
short- and long-range variations on water runoff, soil
erosion and winter wheat production. He took actual
changes in precipitation and temperatures between 1950
and 1999, and those projected for 2056 to 2085, and
constructed five climate-change scenarios showing how
soil erosion and crop production may change if various
climate factors change.
Read more about the research in the July issue of Agricultural
Research magazine, available online at: http://www.ars.usda.gov/is/AR/archive/jul04/rain0704.htm