Morphodynamics of a meandering channel over decadal timescales in response to hydrological variations

Hooke, Janet M ORCID: 0000-0002-8367-3010
(2022) Morphodynamics of a meandering channel over decadal timescales in response to hydrological variations. Earth Surface Processes and Landforms, 47 (8). pp. 1902-1920.

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<jats:title>Abstract</jats:title><jats:p>This article addresses a major theme in fluvial geomorphology on which Professor Ken Gregory contributed much pioneering research, that of quantitative relations of morphological change to discharge variations. It examines the morphodynamics and processes of adjustment of river channels to flow characteristics on event to decadal timescales, using field and remote sensing data collected over a 40‐year period for a very active meandering reach of the River Bollin, northwest England. The free meandering and rapid rates of changes provide insight into response timescales and processes. Morphological variations and rates of change are analysed in relation to peak flow parameters. The results show that the sinuosity has continuously increased since a resetting of the planform by multiple cutoffs in 2001, this autogenic trend underlying the effects of flow events. Width of the channel has varied by 50% between map dates, corresponding to discharge characteristics of each 6‐year period and integrating the impacts of individual events. A trend of decrease in intensity of erosion and deposition and of narrowing for the period 2001–2019 is apparent and may be an indication of the recovery and adjustment time to the major morphological changes in 2001. Other possible influences include decline in sediment supply but no obvious external cause is identified. A feedback effect of lower process rates producing less sediment from banks which decreases rates of channel movement may be occurring. A major contributor to the process rate decline and narrowing could be an increase in riparian vegetation cover. Complex sequences of change between peak flow events emerge, unrelated to discharge magnitude or numbers of peak events, and a process of basal bank sedimentation followed by upper bank deposition is evident. Channel capacity varies by up to 30% year to year, which has major implications for variability of flood risk and floodplain inundation.</jats:p>

Item Type: Article
Uncontrolled Keywords: deposition, erosion, flood, hydromorphology, river channel changes, river meander
Divisions: Faculty of Science and Engineering > School of Environmental Sciences
Depositing User: Symplectic Admin
Date Deposited: 31 Mar 2022 10:28
Last Modified: 06 Sep 2023 00:45
DOI: 10.1002/esp.5354
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