Eyeing Forecast Models' Role for Drier
Times By Luis
July 2, 2004
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
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.
about the research in the July issue of Agricultural Research
ARS is the
U.S. Department of Agriculture's chief
scientific research agency.