Two surface water runoff models (SWAT and MINRUN96) were utilized to
project changes in streamflows in two watersheds under a 2xC02 climate scenario, One
is the Baptism River watershed (363 km2), in northern Minnesota, mainly forested, with a
cold and humid climate, and the other is the Little Washita River watershed, in Oklahoma
(538 km\ an agricultural watershed, with a warm and seasonally dry climate, 2xC02
climate conditions were obtained from the Canadian Climate Center General Circulation
No agreement was evident in the streamflows projected by the two watershed
models for the Baptism River. Snow accumulation and snowmelt were the main
differences between the two models. MINRUN96 simulated the past streamflow more
accurately than SWAT. SWAT includes a biomass submodel which incorporates the
effects of vegetation changes under 2xC02 climate conditions. SWAT also takes into
account the effects of carbon dioxide in the estimation of evapotranspiration, while
MINRUN96 does not contain any algorithm projecting the changes in vegetation or
evapotranspiration due to doubling of atmospheric carbon dioxide. Both models
projected more runoff in the Baptism River watershed in winter due to reduced snowfall
under the 2xC02 climate scenario; however, the magnitudes of the projected increases
were an order of magnitude different. SWAT was developed for agricultural watersheds
and is probably not ,suited for application to forested watersheds at this time.
For the Little Washita River watershed, the streamflows projected by the two
models were in agreement. Both models showed an increase in fall and spring runoff and
a decrease in summer runoff. The two models also proj ected a significant increase in the
mmual streamflow of the Little Washita River under a 2xC02 climate scenario. The
magnitUdes of the projected increases were comparable.
Grazing Land Research Laboratory, US Department of Agriculture; Mid-Continent Ecology Division, US Environmental Protection Agency
Mohseni, O.; Hanratty, M. P.; Stefan, H. G..
Uncertainties in Projecting Stream flows in Two Watersheds Under 2xC02 Climate Conditions.
St. Anthony Falls Laboratory.
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