Coulee, or coulée is a term applied rather loosely to different landforms, all of which refer to a kind of valley or drainage zone. The word coulee comes from the Canadian French coulée, from French couler 'to flow'.
This side canyon of Grand Coulee in Washington was carved by the Missoula floods.
A view through a coulee in Alberta, with steep but lower sides, and water in the bottom.
Drumheller Channels in the Columbia Basin of Washington
A view upward into a coulee in the Oldman River valley in Lethbridge, Alberta
Columbia Plateau (ecoregion)
The Columbia Plateau ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) encompassing approximately 32,100 square miles (83,139 km2) of land within the U.S. states of Washington, Oregon, and Idaho. The ecoregion extends across a wide swath of the Columbia River Basin from The Dalles, Oregon to Lewiston, Idaho to Okanogan, Washington near the Canada–U.S. border. It includes nearly 500 miles (800 km) of the Columbia River, as well as the lower reaches of major tributaries such as the Snake and Yakima rivers and the associated drainage basins. It is named for the Columbia Plateau, a flood basalt plateau formed by the Columbia River Basalt Group during the late Miocene and early Pliocene. The arid sagebrush steppe and grasslands of the region are flanked by moister, predominantly forested, mountainous ecoregions on all sides. The underlying basalt is up to 2 miles (3 km) thick and partially covered by thick loess deposits. Where precipitation amounts are sufficient, the deep loess soils have been extensively cultivated for wheat. Water from the Columbia River is subject to resource allocation debates involving fisheries, navigation, hydropower, recreation, and irrigation, and the Columbia Basin Project has dramatically converted much of the region to agricultural use.
Ice Age floods cut coulees into the basalt of the Channeled Scablands (ecoregion 10a)
Quincy Lake, one of the Pleistocene Lake Basins, is a remnant of the temporary Pleistocene lakes that were created by flood waters from glacial Lake Missoula.
Arrowleaf Balsamroot (Balsamorhiza sagittata), Antelope Bitterbrush (Purshia tridentata) and scattered Ponderosa Pine grow in the Yakima Folds (ecoregion 10g)