Thesis
Characterization of hydrology and water quality at a restored oxbow: ecosystem services achieved in year one
University of Iowa
Master of Science (MS), University of Iowa
Autumn 2017
DOI: 10.17077/etd.678k07k8
Abstract
<p>Conservation practices are needed to reduce nitrate loss across the Midwest. Different riparian wetland designs have been investigated, but the physical, chemical and biological processes controlling nutrient cycling in restored oxbows are not well understood. A restored oxbow’s influence on nutrient cycling was investigated by studying the hydrogeology and water quality at a recently reconstructed oxbow site adjacent to Morgan Creek in Linn County, Iowa. Over a one-year period, the lentic oxbow’s nitrate loading was found to be dominated by flood pulses. Nitrate concentrations in the stream ranged from 7.38 – 12.95 mg l-1, concentrations were consistently low in the oxbow ranging from < 0.10 – 5.35 mg l-1, and the lowest nitrate concentrations were detected in the groundwater ranging from 0.10 to 3.4 mg l-1. Following a spring flood event, an in-situ sensor measured the nitrate concentration in the oxbow. Nitrate retention efficiency was estimated to be 0.30 g N m-2 d-1 or a 74.2% reduction efficiency. The observed nitrate reduction was compared to a first order denitrification model. The observed nitrate reduction measured in the oxbow followed a linear decay rather than an exponential decay suggested by first order kinetics.</p>
Details
- Title: Subtitle
- Characterization of hydrology and water quality at a restored oxbow: ecosystem services achieved in year one
- Creators
- Bryce Jordan Haines - University of Iowa
- Contributors
- Larry J. Weber (Advisor)Keith Schilling (Advisor)Ricardo Mantilla (Committee Member)Chris Jones (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Civil and Environmental Engineering
- Date degree season
- Autumn 2017
- DOI
- 10.17077/etd.678k07k8
- Publisher
- University of Iowa
- Number of pages
- ix, pages
- Copyright
- Copyright © 2017 Bryce Jordan Haines
- Language
- English
- Description illustrations
- color illustrations, color maps
- Description bibliographic
- Includes bibliographical references (pages 90-98).
- Public Abstract (ETD)
Natural streams freely meander throughout floodplains creating ideal habitat conditions for a diverse population of species. Meandering streams have the ability to create oxbows, which are crescent shaped lakes that are cut off from the main channel. Oxbows provide favorable conditions for nutrient reduction, wildlife, flood storage, and recreational uses. However, benefits provided by natural streams have decreased because of land alteration caused by urban development and intense agricultural practices. As a result, stream straightening and channelizing has reduced the formation of new oxbows, and sediment has filled in historic locations. The reduced number has decreased the ecological services once provided by oxbows.
Interest to regain ecosystem services provided by oxbows has resulted in new methods to reconstruct oxbows once filled in with sediment. The restoration process involves excavating out the sediment to increase water storage. As a result, water provides year round habitat for a variety of aquatic and terrestrial species. Auxiliary benefits of restored oxbows include improved water quality because of their ability to retain nutrients due to improved conditions for nutrient cycling. Overall, restored oxbows have been found to be a cost effective option that quickly transition into an ecological hotspot providing habitat, water storage, recreational activities, and nutrient cycling benefits.
- Academic Unit
- Civil and Environmental Engineering
- Record Identifier
- 9983776968702771
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