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Old Man Winter May Rob Banks

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 life.

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 January 2002 issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture’s chief scientific research agency.