Patterns of sediment accumulation in the Siletz River Estuary, Oregon Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/ff365777d

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Anecdotal evidence suggests many Pacific Northwest estuaries are filling with sediment due to historical logging activities in upstream watersheds. Using the Siletz River estuary as a case study, this research began by analyzing timber harvest and discharge records of the Siletz River watershed, and found that increased timber harvest coincides with a period of higher discharge. Based on these findings, sediment flux from the Siletz watershed was expected to have increased and resulted in higher sediment accumulation rates (SARs) in the estuary. To test these assumptions, SARs were estimated using down-core profiles of excess 210Pb and 137Cs from thirty-three cores taken within the estuary. Digital x-radiographs and grain size distributions of cores were used to provide a timeframe for flood deposits and provided further information on retention-related functions of the system. Results indicate minimal evidence for changes in SARs with only two 210Pb profiles and six 137Cs profiles that indicate an increase in deposition attributable to land use and hydroclimatic changes. Calculated SARs (0.18cm/y) were comparable to the rate of local sea level rise (0.19 cm/y), which indicates that retention in the estuary is influenced by the available accommodation space. This finding helps explain the distinct difference in sediment supplied (5.91 x 107 kg/y) to, and retained (8.42 x 106 kg/y) in, the estuary. Overall, this study illuminates the complexity of the forces that influence sediment flux from a watershed and retention within an estuary.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Keyword
Subject
Rights Statement
Language
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Linda Kathman(linda.kathman@oregonstate.edu) on 2009-07-13T14:27:42Z (GMT) No. of bitstreams: 1 Pakenham Thesis final.pdf: 9722434 bytes, checksum: e19c90e05b702075a80662a31e06eb93 (MD5)
  • description.provenance : Made available in DSpace on 2009-07-13T14:27:43Z (GMT). No. of bitstreams: 1 Pakenham Thesis final.pdf: 9722434 bytes, checksum: e19c90e05b702075a80662a31e06eb93 (MD5)
  • description.provenance : Submitted by Anna Pakenham (pakenhaa@onid.orst.edu) on 2009-07-09T00:10:33Z No. of bitstreams: 1 Pakenham Thesis final.pdf: 9722434 bytes, checksum: e19c90e05b702075a80662a31e06eb93 (MD5)
  • description.provenance : Approved for entry into archive by Julie Kurtz(julie.kurtz@oregonstate.edu) on 2009-07-09T17:32:21Z (GMT) No. of bitstreams: 1 Pakenham Thesis final.pdf: 9722434 bytes, checksum: e19c90e05b702075a80662a31e06eb93 (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items