Effects of forest practices on peak flows and consequent channel response
Subtitle: a state-of-the-science report for western Oregon and Washington
By: Gordon E. Grant ... [et al.].
Contributors: Grant, Gordon, 1953-; Pacific Northwest Research Station (Portland, Or.)
Series: General technical report PNW -- GTR-760; General technical report PNW -- 760.
Publisher: U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Research Station
Published: 2008
Place of publication: [Portland, OR]
Language: eng
Number of pages: 76
Subjects: Forest management -- Oregon, Western.; Forest management -- Washington (State), Western.; Forest hydrology -- Oregon, Western.; Forest hydrology -- Washington (State), Western.; Forest influences -- Oregon, Western.; Forest influences -- Washington (State), Western.; Logging -- Environmental aspects -- Oregon, Western.; Logging -- Environmental aspects -- Washington (State), Western.; Watershed hydrology -- Oregon, Western.; Watershed hydrology -- Washington (State), Western.
Description: This is a state-of-the-science synthesis of the effects of forest harvest activities on peak flows and channel morphology in the Pacific Northwest, with a specific focus on western Oregon and Washington. We develop a database of relevant studies reporting peak flow data across rain-, transient-, and snow-dominated hydrologic zones, and provide a quantitative comparison of changes in peak flow across both a range of flows and forest practices. Increases in peak flows generally diminish with decreasing intensity of percentage of watershed harvested and lengthening recurrence intervals of flow. Watersheds located in the rain-dominated zone appear to be less sensitive to peak flow changes than those in the transient snow zone; insufficient data limit interpretations for the snow zone. Where present, peak flow effects on channel morphology should be confined to stream reaches where channel gradients are less than approximately 0.02 and streambeds are composed of gravel and finer material. We provide guidance as to how managers might evaluate the potential risk of peak flow increases based on factors such as presence of roads, watershed drainage efficiency, and specific management treatments employed. The magnitude of effects of forest harvest on peak flows in the Pacific Northwest, as represented by the data reported here, are relatively minor in comparison to other anthropogenic changes to streams and watersheds.
Notes: Cover title.

"May 2008."

Includes bibliographical references (p. 48-64).

Also available on the World Wide Web.