Confluence Environments at the Scale of River Networks

Benda, Lee

doi:10.1002/9780470760383.ch13

Cited by 10 publications

(22 citation statements)

References 47 publications

(84 reference statements)

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“…Nevertheless, empirical analysis of confluence significance across the study area confirmed expectations (Benda et al, 2004a;Benda, 2008) that the number of significant confluences increases with total network length and drainage area. The relation between n 0.8 and A (equation 6) suggests an eight-fold increase in the number of significant confluences for a ten-fold increase in basin area, or a 1.9-fold increase in significant confluences for a doubling of basin area.…”

Section: Discussionsupporting

confidence: 62%

“…The relation between n 0.8 and A (equation 6) suggests an eight-fold increase in the number of significant confluences for a ten-fold increase in basin area, or a 1.9-fold increase in significant confluences for a doubling of basin area. Also as anticipated by Benda et al (2004a) and Benda (2008), basin shape was a strong control of both the number of significant confluences and their spatial distribution: relatively compact basins tended to host a greater number of significant confluences and those confluences were more likely to be distributed across the network. In contrast, relatively linear basins were more likely to have fewer aggradational confluences that were concentrated in proximal reaches.…”

Section: Discussionsupporting

confidence: 52%

“…This is important because it might help to better understand differences in catchment-scale sediment routing and morphological diversity and (to the extent that physical heterogeneity underpins biodiversity) differences in sum, catchment-scale ecological value and resilience. Benda et al (2004a, b) and Benda (2008) 3. How does drainage network size and shape affect the frequency distribution of confluence impact probabilities and, in turn, the likely cumulative magnitude of confluence effects?…”

Section: Outstanding Issues and Aimsmentioning

confidence: 95%

“…The role of basin shape was illustrated using predictions of confluence impact based on equation [2], for two sub-catchments of the Siuslaw River, Oregon, and a systematic analysis revealed an anticipated increase in the spacing between significant confluences with distance downstream along the Siuslaw mainstem. Subsequently, Benda (2008) reflected on these analyses and extended them in several ways, identifying eight testable hypotheses pertaining to the impact of tributaries on mainstem geomorphology.…”

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

confidence: 99%

“…A R , D R , F R ) from digital topographic data. Benda et al (2004a) and Benda (2008) used such an approach to illustrate probable confluence impacts across the Siuslaw watershed, but the results were not systematically evaluated using field data. The first aim of this paper is therefore to:…”

Section: Outstanding Issues and Aimsmentioning

confidence: 99%

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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: Discussionsupporting

confidence: 62%

Section: Discussionsupporting

confidence: 52%

Section: Outstanding Issues and Aimsmentioning

confidence: 95%

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

confidence: 99%

Section: Outstanding Issues and Aimsmentioning

confidence: 99%

See 3 more Smart Citations

Tributary connectivity, confluence aggradation and network biodiversity

Rice

2017

Geomorphology

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Spatial sampling on streams: principles for inference on aquatic networks

et al. 2014

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For ecological and environmental data, prior inquiries into spatial sampling designs have considered two-dimensional domains and have shown that design optimality depends on the characteristics of the target spatial domain and intended inference. The structure and water-driven continuity of streams prompted the development of spatial autocovariance models for stream networks. The unique properties of stream networks, and their spatial processes, warrant evaluation of sampling design characteristics in comparison with their two-dimensional counterparts. Common inference scenarios in stream networks include spatial prediction, estimation of fixed effects parameters, and estimation of autocovariance parameters, with prediction and fixed effects estimation most commonly coupled with autocovariance parameter estimation. We consider these inference scenarios under a suite of network characteristics and stream-network spatial processes. Our results demonstrate, for parameter estimation and prediction, the importance of collecting samples from specific network locations. Additionally, our results mirror aspects from the prior two-dimensional sampling design inquiries, namely, the importance of collecting some samples within clusters when autocovariance parameter estimation is required. These results can be applied to help refine sample site selection for future studies and further showcase that understanding the characteristics of the targeted spatial domain is essential for sampling design planning. Published 2014. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

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Initial hydro‐geomorphic development and rill network evolution in an artificial catchment

Schneider

Gerke

Maurer

et al. 2013

Earth Surf Processes Landf

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The formation of erosion rills and gullies is a critical step in land surface development, but possibilities to study initial unaffected surface development under natural conditions and with well‐defined initial and boundary conditions are rare. The objective of this study was to characterize rill network development from ’point zero’ in the artificially‐created catchment ‘Hühnerwasser’. To ensure unaffected development, the study was largely restricted to the analysis of remotely‐sensed data. We analyzed a series of photogrammetry‐based digital elevation models (DEMs) for 10 points in time, over a period of five years and beginning with the initial state. The evolving erosion rill network was quantitatively described based on mapping from aerial photographs. DEMs and rill network maps were combined to specifically analyze the development of morphometry for different parts of the network and to characterize energy dissipation and connectivity. The restriction to remote‐sensing data did not allow for analyzing specific processes governing rill network development, nevertheless, two major development phases could be characterized. We observed a phase of growth of the rill network along with variations in drainage patterns during the first two years of development and a subsequent phase of reduction of its area along with comparably stable patterns. Region‐specific analysis of morphometry indicates that, besides effects of changing sediment characteristics and vegetation cover development, locally evolving hydro‐geomorphic feedback cycles influenced this development. Results show an increasing similarity of overall statistical characteristics (e.g. drainage density) for two parts of the catchment, but a persistent influence of initial conditions on specific rill geometry. The observed development towards higher orderliness and increased connectivity is consistent with experiments and concepts on drainage network evolution across scales; however, we did not observe major influences of rill piracy and cross grading or a reduction of energy dissipation with network development. Copyright © 2013 John Wiley & Sons, Ltd.

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Confluence Environments at the Scale of River Networks

Cited by 10 publications

References 47 publications

Tributary connectivity, confluence aggradation and network biodiversity

Tributary connectivity, confluence aggradation and network biodiversity

Spatial sampling on streams: principles for inference on aquatic networks

Initial hydro‐geomorphic development and rill network evolution in an artificial catchment

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