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Date Permissions Signed


Date of Award


Document Type

Masters Thesis

Degree Name

Master of Science (MS)


Environmental Studies

First Advisor

Miles, Scott B.

Second Advisor

Bach, Andrew J.

Third Advisor

Terich, Thomas


Landslides are a widely recognized hazard in forested and mountainous terrain. In the Pacific Northwest, these recurrent slope failures cause havoc on an expansive federal forest transportation system that is underfunded and inadequately maintained. Consequently, a need exists for development of techniques that can assist managers in planning and prioritization of U.S. Forest Service (USFS) road management activities. This work explores how new methods of landslide modeling act as decision support tools for mapping landslide susceptibility in roaded areas. Specifically, an original Fuzzybased model using a G.I.S. is created, applied, and evaluated within the context of the Mount Baker-Snoqualmie National Forest. In this approach, a dataset is constructed of nine terrain parameters associated with landslide occurrence. Relationships between historic landslides and predictor datasets are quantified via likelihood ratios and fuzzy membership functions. Using these factors, a fuzzy logic system with fuzzy operators is then applied to assess the relative likelihood of landslide occurrence within the study area. Finally, model outputs in the form of landslide sus ceptibility maps are evaluated using 'area under the curve' technique. Results indicate reasonable predictive capabilities (76% accuracy) comparable to previous research. Following subsequent review of current USFS road policy and procedures, recommendations are made for incorporating model use into USFS Road Maintenance Management Systems and roads analyses required by the Forest Transportation System Management Policy.





Western Washington University

OCLC Number


Subject – LCSH

Landslide hazard analysis--Washington (State)--Mount Baker-Snoqualmie National Forest; Forest roads--Design and construction--Environmental aspects--Washington (State)--Mount Baker-Snoqualmie National Forest; Landslides--Washington (State)--Mount Baker-Snoqualmie National Forest

Geographic Coverage

Mount Baker-Snoqualmie National Forest (Wash.)




masters theses




Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

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