Flood history and sedimentation at the mouth of Redwood Creek, Humboldt County, California Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/8336h520q

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Since the early 1950's, the distribution of sediment at the mouth of Redwood Creek has been altered by the effects of channel aggradation and channelization along the lower reach. Severe flooding in 1953, 1955, and 1964 caused bank erosion, landsliding, and channel geometry changes along Redwood Creek. The increased sediment load resulted in channel aggradation and widening along the lower floodplain. Flood control levees constructed from 1966 to 1968 channelized the lower reach of Redwood Creek and extended beyond the last downstream meander. The distribution of erosional and depositional sites at the mouth has been more drastically altered by the effects of channelization than of aggradation. Channelization was accompanied by removal of bed roughness elements, shaping a trapezoidal channel with an increased hydraulic radius, and steepening the channel gradient. This caused an increase in the mean velocity and frequency of mobilization of the substrate between the levees. With streamflow confined between the levees, sediments deposited in the last downstream meander (south slough) and north slough are no longer flushed from the mouth of Redwood Creek. Since 1966, 47-54 percent of the lower estuary (between 0 and 4 feet above MSL) has filled with sediment or become isolated from the embayment. Sediment yield of Redwood Creek is among the highest for a basin of its size in North America, but under present conditions fluvial sediment is not accumulating at the mouth. Heavy mineral and textural data indicate that during high to moderate streamflow, sand and gravel-sized sediment is flushed through the embayment. Overwash across the storm berm and tidal current transport are the dominant processes of deposition in the sloughs, delivering marine sediment to the estuary. Sediment accumulation has also altered the seasonal sequence of migration and closure of the outflow channel which determines the embayment water volume, substrate distribution and water quality during the low flow period from spring to early fall. More frequent closure and flooding of backwater areas and adjacent pastures has historically led to artificial breaching of the berm. In the past, such premature breaching released 75 percent of the embayed water volume being used by 20,000 juvenile salmonids for summer rearing habitat.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using Capture Perfect 3.0 on a Canon DR-9050C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-10-07T22:13:37Z (GMT) No. of bitstreams: 1 RicksCynthiaL1984.pdf: 8614115 bytes, checksum: 6a12daa83a1e191b4c214053756ae6af (MD5)
  • description.provenance : Submitted by Kirsten Clark (kcscannerosu@gmail.com) on 2013-07-31T21:46:44Z No. of bitstreams: 1 RicksCynthiaL1984.pdf: 8614115 bytes, checksum: 6a12daa83a1e191b4c214053756ae6af (MD5)
  • description.provenance : Made available in DSpace on 2013-10-07T22:13:37Z (GMT). No. of bitstreams: 1 RicksCynthiaL1984.pdf: 8614115 bytes, checksum: 6a12daa83a1e191b4c214053756ae6af (MD5) Previous issue date: 1983-06-09
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-08-01T14:23:26Z (GMT) No. of bitstreams: 1 RicksCynthiaL1984.pdf: 8614115 bytes, checksum: 6a12daa83a1e191b4c214053756ae6af (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items