Abundance, Mobility, and Geomorphic Effects of Large Wood in Urban Streams

Bibliographic Details
Main Author:	Blauch, Garrett
Language:	English
Published:	Kent State University / OhioLINK 2018
Subjects:	Geomorphology Hydrology large wood urban streams geomorphology
Online Access:	http://rave.ohiolink.edu/etdc/view?acc_num=kent1532016674833626

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spelling	ndltd-OhioLink-oai-etd.ohiolink.edu-kent15320166748336262021-08-03T07:07:43Z Abundance, Mobility, and Geomorphic Effects of Large Wood in Urban Streams Blauch, Garrett Geomorphology Hydrology large wood urban streams geomorphology Large wood plays important roles in the geomorphology and ecology of streams, with benefits for pool spacing, streambed sediment, bank erosion, habitat creation, and nutrient retention. Urbanization, and the impervious surface cover associated with it, generates stormwater runoff that is routed quickly into streams, which is often detrimental to the physical and biological health of the streams. Stormwater runoff causes higher peak flow magnitudes, flashier hydrographs, and can lead to elevated rates of incision, channel widening, and loss of channel complexity. A lack of large wood in urban streams could be a result of either loss of recruitment potential as riparian forests are replaced by other land covers or increased mobility from flashy streams flushing out large wood. Controlling for the effects of wood recruitment potential by working in reaches with forested riparian zones allows for the effects of the urban hydrograph on wood abundance to be tested. For this study, I selected 11 stream reaches flowing through protected forested riparian zones in northeast Ohio with a range of impervious surface covers. Large wood (1.0 m length, 0.1 m diameter) was catalogued with respect to size and orientation within bankfull channels. Reaches were surveyed for geomorphic features including bankfull dimensions, streambed topography, sediment size, and bank erosion to determine associations between wood abundance and geomorphology. Wood abundances decreased with increasing watershed impervious cover, with a majority of wood stored in jams. Most large wood was less than 5 m in length and had a diameter less than 20 cm. The portion of mobile pieces (gained or lost from the reach) increased with impervious surface cover, suggesting higher mobility of wood in flashier urban systems. Reach-scale trends between large wood abundance and geomorphology were not evident. Pool spacing increased linearly with jam spacing in the six reaches that had jams. Wood-associated fine sediment trapping was also documented in some reaches. While the opportunity for wood recruitment was maintained in each reach, wood abundance was still decreased at higher impervious covers. In the reaches with moderate to high impervious cover, decreased wood abundance, high wood mobility, and the relatively small size of wood pieces may indicate that large wood is not remaining in the reaches long enough to make a substantial impact on channel geomorphology. If large wood is considered in urban stream restoration, the stability of pieces, dictated by a large wood size relative to bankfull channel dimensions and anchoring in the channel, is crucial for providing the best chance for the physical and ecological benefits of wood to be realized. Efforts to protect forested riparian zones throughout the urban watersheds and decrease peak flows and stormwater runoff may also be necessary to further increase wood abundance and reduce the potential for wood mobilization. 2018-07-20 English text Kent State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=kent1532016674833626 http://rave.ohiolink.edu/etdc/view?acc_num=kent1532016674833626 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection	NDLTD
language	English
sources	NDLTD
topic	Geomorphology Hydrology large wood urban streams geomorphology
spellingShingle	Geomorphology Hydrology large wood urban streams geomorphology Blauch, Garrett Abundance, Mobility, and Geomorphic Effects of Large Wood in Urban Streams
author	Blauch, Garrett
author_facet	Blauch, Garrett
author_sort	Blauch, Garrett
title	Abundance, Mobility, and Geomorphic Effects of Large Wood in Urban Streams
title_short	Abundance, Mobility, and Geomorphic Effects of Large Wood in Urban Streams
title_full	Abundance, Mobility, and Geomorphic Effects of Large Wood in Urban Streams
title_fullStr	Abundance, Mobility, and Geomorphic Effects of Large Wood in Urban Streams
title_full_unstemmed	Abundance, Mobility, and Geomorphic Effects of Large Wood in Urban Streams
title_sort	abundance, mobility, and geomorphic effects of large wood in urban streams
publisher	Kent State University / OhioLINK
publishDate	2018
url	http://rave.ohiolink.edu/etdc/view?acc_num=kent1532016674833626
work_keys_str_mv	AT blauchgarrett abundancemobilityandgeomorphiceffectsoflargewoodinurbanstreams
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Abundance, Mobility, and Geomorphic Effects of Large Wood in Urban Streams

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