Geomorphological analysis of North Fork Toutle River, Washington, 1980-1984 Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/8c97ks56g

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • The 18 May 1980 eruption of Mount St. Helens, emplaced between 3-3.5 billion cubic yards (bcy) of poorly sorted material ranging from silt to boulders, extending from river mile (RM) 25 to RM 38 in the upper North Fork Toutle River drainage. Sediment yields from the debris avalanche were calculated for four water years, 1980-1983. During 1980, the North Fork Toutle River reestablished a main channel from RM's 20 to 27, yielding 15 million cubic yards (mcy). In 1981 the channel network lengthened by head cutting, and the network was further integrated to pond and lake breaches on the debris avalanche. Channel length and width increased with winter storms. Within the channel area, braiding and incision were the major processes which yielded 31.5 million cubic yards of sediment. Channel widening, associated with braiding, incision, and bank failure were the dominant geomorphic processes during 1981 and 1982. By 1982, the North Fork Toutle headwaters had extended to the topographic divide at Spirit Lake. Related to this headward growth, sediment yields from the upper 7 river miles of the debris avalanche increased. This accelerated erosion induced a cascading hydrologic effect, increasing sediment yields to 34.1 mcy during 1982. By 1983, channel widening slowed and aggredation increased in the lower 8 river miles, facilitating an overall increase in sediment storage. Establishment of a stable ground water table within the debris avalanche and reduced channel incision induced a decreased bank failure and sediment transport promoting channel stabilization. This increased stability resulted in a 15.1 million cubic yard reduction in sediment yield, producing a net yield of 19.0 mcy. The North Fork Toutle River long profile showed rapid incision from 1980-1982. While 1982-1983 showed definite smoothing and concave profile development. Profile plots for 1982 and 1983 show that the system adjusted toward the sediment load and hydrologic conditions in the study area. A total of 99.4 million cubic yards of sediment was calculated to have been derived from the debris avalanche between 19 May 1980 - September 1983.
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Publisher
Peer Reviewed
Language
Digitization Specifications
  • Master files scanned at 600 ppi (256 Grayscale) using Capture Perfect 3.0 on a Canon DR-9080C in TIF format. PDF derivative scanned at 300 ppi (256 B+W), using Capture Perfect 3.0, on a Canon DR-9080C. CVista PdfCompressor 3.1 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Linda Kathman(linda.kathman@oregonstate.edu) on 2008-07-21T21:59:23Z (GMT) No. of bitstreams: 1 Pearson_Monte_L_1985.pdf: 1520862 bytes, checksum: 59051785a1ddccd1cbb744779fd550b6 (MD5)
  • description.provenance : Approved for entry into archive by Linda Kathman(linda.kathman@oregonstate.edu) on 2008-07-21T22:01:36Z (GMT) No. of bitstreams: 1 Pearson_Monte_L_1985.pdf: 1520862 bytes, checksum: 59051785a1ddccd1cbb744779fd550b6 (MD5)
  • description.provenance : Submitted by Adam Powell (apscanner@gmail.com) on 2008-07-14T22:27:35Z No. of bitstreams: 1 Pearson_Monte_L_1985.pdf: 1520862 bytes, checksum: 59051785a1ddccd1cbb744779fd550b6 (MD5)
  • description.provenance : Made available in DSpace on 2008-07-21T22:01:37Z (GMT). No. of bitstreams: 1 Pearson_Monte_L_1985.pdf: 1520862 bytes, checksum: 59051785a1ddccd1cbb744779fd550b6 (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items