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  • 1
    Online Resource
    Online Resource
    Wiley ; 2017
    In:  Earth Surface Processes and Landforms Vol. 42, No. 12 ( 2017-09-30), p. 1872-1883
    In: Earth Surface Processes and Landforms, Wiley, Vol. 42, No. 12 ( 2017-09-30), p. 1872-1883
    Abstract: The ability to quantify the processes driving geomorphic change in river valley margins is vital to geomorphologists seeking to understand the relative role of transport mechanisms (e.g. fluvial, aeolian, and hillslope processes) in landscape dynamics. High‐resolution, repeat topographic data are becoming readily available to geomorphologists. By contrasting digital elevation models derived from repeat surveys, the transport processes driving topographic changes can be inferred, a method termed ‘mechanistic segregation.’ Unfortunately, mechanistic segregation largely relies on subjective and time consuming manual classification, which has implications both for its reproducibility and the practical scale of its application. Here we present a novel computational workflow for the mechanistic segregation of geomorphic transport processes in geospatial datasets. We apply the workflow to seven sites along the Colorado River in the Grand Canyon, where geomorphic transport is driven by a diverse suite of mechanisms. The workflow performs well when compared to field observations, with an overall predictive accuracy of 84% across 113 validation points. The approach most accurately predicts changes due to fluvial processes (100% accuracy) and aeolian processes (96%), with reduced accuracy in predictions of alluvial and colluvial processes (64% and 73%, respectively). Our workflow is designed to be applicable to a diversity of river systems and will likely provide a rapid and objective understanding of the processes driving geomorphic change at the reach and network scales. We anticipate that such an understanding will allow insight into the response of geomorphic transport processes to external forcings, such as shifts in climate, land use, or river regulation, with implications for process‐based river management and restoration. Copyright © 2017 John Wiley & Sons, Ltd.
    Type of Medium: Online Resource
    ISSN: 0197-9337 , 1096-9837
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 1479188-2
    SSG: 14
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  • 2
    Online Resource
    Online Resource
    Wiley ; 2022
    In:  Earth Surface Processes and Landforms Vol. 47, No. 1 ( 2022-01), p. 257-274
    In: Earth Surface Processes and Landforms, Wiley, Vol. 47, No. 1 ( 2022-01), p. 257-274
    Abstract: Given the complex array of processes influencing river networks, conceptual frameworks of rivers are critical to our understanding of channel processes and response potential, as well as restoration efforts. Yet despite their wide usage, many classifications are based on limited observations over homogenous landscapes, raising questions about their general applicability and quantitative thresholds. Leveraging a large, transect‐based morphological field dataset across California, USA, we use data‐driven methods to evaluate multivariate patterns in channel morphology and linkages with landscape properties considering a diversity of physio‐climatic settings. Emergent patterns highlight the variability in channel form observed across an extensive dataset over heterogeneous but spatially linked watersheds. In general, identified dominant channel attributes and landscape properties align with established channel types defined through expert judgement, but key differences also emerge. Similar to past studies, bed sediment composition and sub‐reach depth variability were discriminating channel attributes. The dominance of landscape properties associated with sediment supply or transport capacity suggests that morphological diversity largely reflects these differences as posited by prior classifications. Results also show some channel forms to be largely independent of valley confinement, with several channel bedforms and dominant grain sizes occurring across valley settings. This data analysis study demonstrates the utility of considering channel reaches and landscapes as multi‐dimensional features to elucidate and test established geomorphic understanding over large field datasets.
    Type of Medium: Online Resource
    ISSN: 0197-9337 , 1096-9837
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 1479188-2
    SSG: 14
    Location Call Number Limitation Availability
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  • 3
    In: Ecohydrology, Wiley, Vol. 15, No. 6 ( 2022-09)
    Abstract: The effects of river regulation on the flow patterns of rivers in western North America often mimic the impacts of naturally occurring episodic drought. On the Dolores River in southwestern Colorado, two distinct periods of flow modification have occurred, with very different drought‐like consequences for downstream habitat. The first period of major irrigation diversions (1889–1984) led to extreme low flows during the summer months with little change to spring peak flows. The second period after dam construction (1984 to present) caused a decline in peak flows but an increase in summer minimum flows. We studied the role of these different flow regimes in promoting the recruitment of non‐native tamarisk, since understanding historic patterns of recruitment may inform current and future flow management. We used dendrochronology to determine tamarisk establishment dates and tested the connection between establishment years and a suite of hydroclimatic variables. Tamarisk recruitment occurred between 1952 and 2002, with 92% of trees establishing during the first flow diversion period. The strongest hydroclimate predictor was low minimum flow for a given year, especially when coupled with higher peak flows in the year of, or before, establishment. Almost no tamarisk recruitment has occurred in the second, dam‐controlled period, where lowered peak flows and elevated minimum flows prevail. In spite of the drought tolerance of tamarisk, drought‐like conditions below this dam did not promote its invasion. Instead, the combination of lowered peaks but increased summer baseflows post‐dam has driven channel narrowing and vegetation encroachment by native willows. What current and future meteorologic drought conditions, coupled with dam‐controlled flows, will bring to the channel and adjacent riparian vegetation is uncertain, but this work may help to forecast the impacts of future river flows on riparian vegetation community evolution.
    Type of Medium: Online Resource
    ISSN: 1936-0584 , 1936-0592
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2418105-5
    SSG: 12
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