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Winter May Rob Banks
By Don Comis
January 24, 2002
Once a week, no matter the weather,
farmer Alan Pipal walks to the Missouri River on his Montana farm and jabs a
tall measuring stick into the snow and ice covering the river.
Pipal's hardy observations help Agricultural Research Service scientists
and the U.S. Army Corps of Engineers better understand how winter weather might
help the Missouri River steal his and other farmers land.
The researchers have already seen that ice seems to be one of the causes of
increased river flow that can gut river beds and collapse river banks, not only
eroding land but also causing sand accumulations that can clog pumps that use
river water to irrigate crops. Boone Whitmer, who farms 3,000 acres of wheat
and alfalfa near Wolf Point, Mont., lost a $20,000 pump because of such
clogging, which can happen over just one winter and spring.
Ice is an important factor in a river's overall behavior. Pipal's frequent
measurements help scientists and engineers learn how ice forms, how thick it
gets, and how that affects river flow, with the subsequent effects on riverbed
erosion and downstream silting.
Thick ice that melts quickly in a warm spring can dramatically increase
river flow. As the bed erodes and lowers, more of the riverbank is exposed.
Without the countervailing pressure of water, the upper layer of bank often
collapses into the river. Valuable farmland is lost that way, and the river is
polluted with sediment that chokes not only irrigation pumps, but also aquatic
Pipal's earlier measurements are included in a guide to erosion problems on
the Missouri River in Montana, between Fort Peck Dam and the North Dakota
border. The Missouri is one of North America's 10 most endangered rivers.
For more details, see the
2002 issue of Agricultural
ARS is the U.S. Department of
Agricultures chief scientific research agency.