Year of Award


Document Type


Degree Type

Master of Science (MS)

Degree Name


Department or School/College

College of Forestry and Conservation

Committee Chair

Donald F. Potts


University of Montana


A knowledge of natural erosion rates of the Belt Series of western Montana is a prerequisite to the prescription of "best management practices" by the forest industry of the region. Suspended sediment yield, as an index of erosion, was determined for a single drainage basin on quartzitic and argillaceous members of the Missoula Group, using discharge and sediment concentration measurements from two stations. Physical and biotic features relevant to erosion were quantified for the undisturbed basin.

Sediment yields of 0.18 tons/km2yr were estimated for the year July 1982 till June 1983. Comparison with other measurements on this geology, and with predictions from two models, show this yield to be very low. Low yields are explained by the minimal surface run-off and overland delivery of eroded material, the stability of the soils and the extensive ground cover. Channel erosion is indicated as the principal source of measured sediment.

The representativeness of the study basin in terms of its morphology was tested against a sample of 107 basins in western Montana. Above normal drainage density, relief and elongation are not reflected in the sediment yields. Use of multivariate techniques on the pool of morphometric variables showed little tendency towards uniformity of basin structure within geographic locations or third level land system classification units.



© Copyright 1983 David Findlay Scott