Characterization of the Shallow Subsurface Geohydrology of the Ni-les'tun Unit on the Bandon Marsh National Wildlife Refuge

Author

Christopher Madison Beard, Portland State UniversityFollow

Sponsor

Portland State University. Department of Geology

First Advisor

Curt Peterson

Term of Graduation

Spring 2013

Date of Publication

7-24-2013

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Geology: Geohydrology

Department

Geology

Language

English

Subjects

Water quality -- Oregon -- Bandon Marsh National Wildlife Refuge -- Measurement, Marsh conservation -- Oregon -- Bandon Marsh National Wildlife Refuge, Wetland restoration -- Oregon -- Bandon Marsh National Wildlife Refuge, Wildlife conservation

DOI

10.15760/etd.1060

Physical Description

1 online resource (vii, 91 pages)

Abstract

The Bandon Marsh is a large marsh restoration project located in southwest Oregon. The land has been previously used for dairy farms and much of the marsh was used for cattle grazing. The goal of the restoration is to recreate a natural habitat for shorebirds and fish. The purpose of this thesis is to gather and analyze data on the geology of the marsh and both ground and surface water quality to evaluate its ability to support biology.

The US Fish and Wildlife Service began restoration on the Bandon marsh in 2005. Research on the Ni-les'tun Unit began in that same year with Geoprobe coring, Ground Penetrating Radar (GPR), piezometer well installation, and surface water analysis. Twelve cores were taken with the Geoprobe in 2006 and later analyzed for this thesis. A total of 50 GPR lines were run across the marsh ranging from ~25 m to 1,200 m in length for a total of about 9,700 meters (9.7 km). The ten piezometer wells were sampled to collect groundwater pH, oxidation-reduction potential, salinity, temperature, and well water elevation. Twelve channel sampling sites were chosen to be sampled in three field runs taking place in winter 2011, summer 2011, and winter 2012. The summer 2011 and winter 2012 sampling runs were done after tide gates had been removed from the marsh.

The Geoprobe core samples were retrieved for extensive lab analysis. Analyses included; bulk density, porosity, permeability, and grain size studies. Lab results revealed a low permeability fine grained upper sedimentary unit ranging from ~0.5 to ~2.5 meters depth with a coarser grained higher permeability lower unit. GPR lines were analyzed for groundwater surface depths and buried channel cut and fill features (Peterson et. al., 2004). GPR results showed a fairly shallow groundwater surface around 0.5 meters in the north down to 2.0 meters in the south.

The piezometer wells showed a seasonal variation in well water elevation with higher elevations in the winter and lower in the summer. Well water chemistry showed both seasonal and spatial variations. Values for pH and dissolved oxygen were lower in the north side of the marsh and higher in the south side, and pH was higher in the summer than in the winter. Wells that were more proximal (within ~400 m) to the Coquille River Estuary showed higher conductivity (salinity) values than those that were more distal (greater than ~400 m).

Channel sampling results showed similar trends as the groundwater results. The lower pH values tended to be in the north side of the marsh as well as lower dissolved oxygen values. Again, there was a spatial variability in conductivity with the higher values found closer to the Coquille River. Conductivity in the channel water showed a great seasonal variability with the highest values occurring in the summer time and much lower values in the winter. As expected, channel water increased about 10°C on average from winter to summer.

The results of all of these observations and analyses are combined to put together a generalized flow model showing the different water inputs into the channel waters on the Ni-les'tun Unit. Once these inputs were derived, conclusions can be made on the quality of the water and its ability to support small aquatic life.

Rights

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Persistent Identifier

http://archives.pdx.edu/ds/psu/15337

Recommended Citation

Beard, Christopher Madison, "Characterization of the Shallow Subsurface Geohydrology of the Ni-les'tun Unit on the Bandon Marsh National Wildlife Refuge" (2013). Dissertations and Theses. Paper 1060.
https://doi.org/10.15760/etd.1060