Effects of Tributaries on Main‐Channel Geomorphology

Ferguson, Rob; Hoey, Trevor

doi:10.1002/9780470760383.ch10

Cited by 29 publications

(36 citation statements)

References 40 publications

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“…In addition to this empirical work, conceptual models of alluvial regime, for example Lane (1955), and theoretical investigations for both sand-and gravel-bed rivers (Ferguson and Hoey, 2008), suggest that mainstem responses to tributaries are governed by the ratios of that the product F R .D R was the key determinant of such heterogeneity, while the momentum ratio Q R was less important . This result is consistent with field observations showing that tributaries which introduce large amounts of relatively coarse material are associated with mainstem storage, aggradation, upstream slope reduction and downstream slope increases (e.g.…”

Section: Controls Of Tributary-driven Aggradation -Which Tributaries mentioning

confidence: 83%

Tributary connectivity, confluence aggradation and network biodiversity

Rice

2017

Geomorphology

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In fluvial networks, some confluences are associated with tributary-driven aggradation where coarse sediment is stored, downstream sediment connectivity is interrupted and substantial hydraulic and morphological heterogeneity is generated. To the extent that biological diversity is supported by physical diversity, it has been proposed that the distribution and frequency of tributary-driven aggradation is important for the magnitude and spatial structure of river biodiversity. Relevant ideas are formulated within the Link Discontinuity Concept and the Network Dynamics Hypothesis, but many of the issues raised by these conceptual models have not been systematically evaluated. This paper first tests an automated method for predicting the likelihood of tributary-driven aggradation in three large drainage networks in the Rocky Mountain foothills, Canada. The method correctly identified approximately 75% of significant tributary confluences and 97% of insignificant confluences. The method is then used to evaluate two hypotheses of the Network Dynamics Hypothesis: that linear-shaped basins are more likely to show a longitudinal, downstream decline in tributary-driven aggradation; and that larger and more compact basins contain more confluences with a high probability of impact. The use of a predictive model that included a measure of tributary basin sediment delivery, rather than symmetry ratio alone, mediated the outcomes somewhat, but as anticipated, the number of significant confluences increased with basin size and basin shape was a strong control of the number and distribution of significant confluences. Doubling basin area led to a 1.9-fold increase in the number of significant confluences and compact basins contained approximately twice as many significant confluences per unit channel length as linear basins. In compact basins, significant confluences were more widely distributed, whereas in linear basins they were concentrated in proximal reaches. Interesting outstanding issues include the possibility of using spatially-distributed sediment routing models to predict tributary-driven confluence aggradation and the need to gather ecological data sufficient to properly test for increases in local and network-scale biodiversity associated with significant confluences and their network-scale controls.

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Section: Controls Of Tributary-driven Aggradation -Which Tributaries mentioning

confidence: 83%

Tributary connectivity, confluence aggradation and network biodiversity

Rice

2017

Geomorphology

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“…This highlights the influence of valley confinement and the composition and configuration of geomorphic units as key determinants of channel sensitivity to adjustment. Other than reach-scale characteristics, channel network attributes such as the distribution and nature of tributary confluences and associated influences upon flow/sediment inputs, influence local (reach or 'sediment-link' scale) responses to flood events (e.g., Ferguson et al, Table 3 Volume 2006; Ferguson and Hoey, 2008). These relationships are also influenced by longitudinal connectivity between reaches (Hooke, 2003).…”

Section: Geomorphic Responses To Flood Events In Confined and Unconfimentioning

confidence: 96%

“…Tributary factors may have reduced the impact of increasing sediment input for reach JWB ( Fig. 1; see Ferguson and Hoey, 2008). Water flow with high suspended load is able to be transferred through Sipan Dam to the downstream reach when the dam is releasing.…”

Section: Geomorphic Responses To Flood Events In Confined and Unconfimentioning

confidence: 96%

Monitoring channel responses to flood events of low to moderate magnitudes in a bedrock-dominated river using morphological budgeting by terrestrial laser scanning

Brierley

Chang

2015

Geomorphology

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“…Fan area was more strongly related to the ratio of tributary to mainstem basin area ( Figure 11F), implying that the discharge ratio controls fan growth and persistence. Best, 1988;Biron et al, 1993;Boyer et al, 2006;Ferguson and Hoey, 2008;Guillén-Ludeña et al, 2016;Mosley, 1976). Best, 1988;Biron et al, 1993;Boyer et al, 2006;Ferguson and Hoey, 2008;Guillén-Ludeña et al, 2016;Mosley, 1976).…”

Section: Tributary Basin Morphometrymentioning

confidence: 99%

Tributary‐junction fans as buffers in the sediment cascade: a multi‐decadal study

Leenman

Tunnicliffe

2020

Earth Surf Processes Landf

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Alluvial fans at tributary junctions modulate sediment flux through river networks, by buffering the mainstem channel from disturbance in the tributaries. Buffering occurs through the storage (and release) of sediment in fans. Here, we use an extensive historic dataset to characterise the ways in which fan buffering can change as sediment supply varies. In New Zealand's East Coast region, sediment supply and fluvial transport are prolific by global standards. We reconstruct how tributary‐junction fans in this region have responded to sediment generated by deforestation and extreme storms. The dynamics of five fans along the Tapuaeroa River are examined for the period 1939–2015. In response to major sediment loading, fans aggraded by up to 12 m and prograded by up to 170 m. Net sediment accumulation ranged from near zero to 1.5×106 m3. Fan size, gradient, sediment storage and buffering were influenced by both upstream and downstream controls. Key upstream (tributary) influences were sediment supply and stream power; downstream (mainstem) influences included distal confinement and, importantly, the nature of fan interaction with the mainstem, which aggraded by up to 6 m. The fans' ability to buffer the Tapuaeroa River from change in the tributaries was largely governed by this downstream interaction: as the mainstem aggraded, it increasingly curtailed fan progradation, thus limiting buffering. Previous studies of tributary‐junction fans have related fan morphometry to basin characteristics. However, we find that fan slope and area can vary considerably at decadal, annual or even monthly timescales. Consequently, we suggest that such studies could benefit by examining regional histories of disturbance. © 2019 John Wiley & Sons, Ltd.

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Effects of Tributaries on Main‐Channel Geomorphology

Cited by 29 publications

References 40 publications

Tributary connectivity, confluence aggradation and network biodiversity

Tributary connectivity, confluence aggradation and network biodiversity

Monitoring channel responses to flood events of low to moderate magnitudes in a bedrock-dominated river using morphological budgeting by terrestrial laser scanning

Tributary‐junction fans as buffers in the sediment cascade: a multi‐decadal study

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