Graduate Thesis Or Dissertation
 

Hydrologic factors and environmental impacts of mass soil movements in the Oregon Coast Range

Público Deposited

Conteúdo disponível para baixar

Baixar PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/fn107235k

Descriptions

Attribute NameValues
Creator
Abstract
  • Mass soil movements of four types; debris avalanche, debris torrent, debris slide and bank slough, were field inventoried in the Oregon Coast Range. A total of 104 mass movements were located in 21 undisturbed watersheds and 13 clearcuts harvested in the last six years. Failures associated with roads and landings were not included in this inventory. Failure volume ranged from 2 yd³ to 196 yd³. The average volume of all failure types ten cubic yards or more in volume is 41 yd³ in undisturbed watersheds and 47 yd³ in clearcuts. Failures less than ten cubic yards are of little significance in terms of initial volume moved, but in undisturbed watersheds they account for over one-fourth of the channel impact by mechanical scour and deposition. The frequency of all failures is similar in clearcuts and undisturbed watersheds, one in 19 acres and one in 17 acres, respectively. Mass failures travel 1.7 times farther in clearcuts than in undisturbed watersheds. Debris jams from failures in clearcuts contain. 3.2 times more inorganic and 2.5 times more organic debris than debris fans from undisturbed watersheds. Eight percent of the Class III and IV stream length (U. S Forest Service Classification) in forested drainages and ten percent of that within clearcuts is impacted by channel scour and deposition. The erosion rate for all soil landtypes encountered in undisturbed 3 watersheds is 0.11 yd³/ac/yr. This rate increases by 3.5 times in clearcuts. Landtypes with very steep, highly dissected slopes show the largest increase in erosion rate from uncut to clearcut watersheds (10 times). Less than one percent of the forested or clearcut land area is affected by the mass soil movements. Half of the failures in undisturbed drainages and nine-tenths of the failures in clearcuts occurred on slopes of 80 percent or greater. The average volume of failures is greatest on slopes of 80 to 100 percent. No apparent relation exists between. failure frequency and aspect in this study. The results are compared with other studies in. the Pacific Northwest and the differences are discussed. Natural variation accounts for much of the differences. Guidelines are given for assessing the risk of damage by debris avalanche and torrent type failures in proposed timber harvest areas.
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Subject
Declaração de direitos
Publisher
Peer Reviewed
Language
Digitization Specifications
  • PDF derivative scanned at 300 ppi (256 B&W), using Capture Perfect 3.0, on a Canon DR-9080C. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces

Relações

Parents:

This work has no parents.

Em Collection:

Itens

Miniatura Título Data de carga Acesso Ações
file details Ketcheson_Gary_L_1977.pdf 2017-08-19 Público Baixar