Spatial Identification of Tributary Impacts in River Networks

Torgersen, Christian E.; Gresswell, Robert E.; Bateman, Douglas S.; Burnett, Kelly M.

doi:10.1002/9780470760383.ch9

Cited by 20 publications

(18 citation statements)

References 76 publications

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“…In addition, excess sediment is available to build bedforms that add flow complexity and mesohabitats, and bed material sorting may generate diverse substrate characteristics (grain size, stability, microtopography, near-bed hydraulics) over short distances. This type of increased local heterogeneity at confluences has been associated with discontinuities in the longitudinal distribution and diversity of invertebrates Knispel and Castella, 2003), periphyton and fish (Kiffney et al 2006;Torgersen et al, 2008). In addition, the juxtaposition of contrasting physical conditions between the tributary, upstream and downstream links may offer unique opportunities for mobile taxa (Power and Dietrich, 2002), including for example, local (and therefore low-cost) access to contrasts in illumination, substrate stability, turbidity, predator avoidance and water temperature (Kupferberg, 1996;Scrivener et al, 1994;Fraser et al, 1995;Cairns et al, 2005;Katano et al, 2009;Taverny et al, 2012).…”

Section: Tributary-driven Aggradation In River Networkmentioning

confidence: 99%

“…Various approaches to this problem could be taken, including the application of spatially distributed numerical models of sediment transfer processes (e.g. Gasparini, 1999;Sklar et al, 2006;Czuba and Foufoula-Georgiou, 2015) or the statistical interrogation of high-resolution or continuous, longitudinal data (Torgersen et al, 2008). Here, the approach adopted by Rice (1998) and Benda et al, (2004a) is pursued.…”

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: Tributary-driven Aggradation In River Networkmentioning

confidence: 99%

Section: Outstanding Issues and Aimsmentioning

confidence: 99%

Tributary connectivity, confluence aggradation and network biodiversity

Rice

2017

Geomorphology

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“…According to the river continuum concept (Vannote et al, 1980), intensive surveys usually detect dominant gradients in spatial structures, such as the broad-scale longitudinal pattern in hydraulic geometry (Leopold and Maddock, 1953) or fluvial pattern (Beechie et al, 2006). Nevertheless, downstream interruptions in longitudinal trends, due for example to confluences (Rice, 1998;Benda et al, 2004;Torgersen et al, 2008) or geological controls (Schumm and Spitz, 1996;Ferguson and Brierley, 1999;Piégay et al, 2000;Phillips, 2008), are now well documented in specific cases. Rivers are increasingly viewed as discontinuum (Perry and Schaeffer, 1987;Montgomery, 1999), which are strongly organized into a hierarchical arrangement of ecosystems (Frissell et al, 1986).…”

Section: Introductionmentioning

confidence: 95%

Spatial disaggregation and aggregation procedures for characterizing fluvial features at the network-scale: Application to the Rhône basin (France)

2011

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“…() and Torgersen et al. () subsequently found effects of tributary confluences on water temperature, habitat quality, and fish distribution. Olden and Naiman () state, “The management of riverine landscapes for thermal integrity will require a broad perspective that recognizes the heterogeneous nature in which the topology of the drainage network controls the physical processes shaping spatial and temporal variability in stream temperatures.” Network topology has been implicated in colonization dynamics and species distributions (Martin and Petty , Della Croce et al.…”

Section: Introductionmentioning

confidence: 97%

Simulated juvenile salmon growth and phenology respond to altered thermal regimes and stream network shape

et al. 2017

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Abstract. It is generally accepted that climate change will stress coldwater species such as Pacific salmon. However, it is unclear what aspect of altered thermal regimes (e.g., warmer winters, springs, summers, or increased variability) will have the greatest effect, and what role the spatial properties of river networks play. Thermally diverse habitats may afford protection from climate change by providing opportunities for aquatic organisms to find and use habitats with optimal conditions for growth. We hypothesized that climate-altered thermal regimes will change growth and timing of life history events such as emergence or migration but that changes will be moderated in topologically complex stream networks where opportunities to thermoregulate are more readily available to mobile animals. Because climate change effects on populations are spatially variable and contingent upon physiological optima, assessments of risk must take a spatially explicit approach. We developed a spatially structured individual-based model for Chinook Salmon (Oncorhynchus tshawytscha) in which movement decisions and growth were governed by water temperature and conspecific density. We evaluated growth and phenology (timing of egg emergence and smolting) under a variety of thermal regimes (each having a different minimum, rate of warming, maximum, and variability) and in three network shapes of increasing spatial complexity. Across networks, fish generally grew faster and were capable of smolting earlier in warmer scenarios where water temperatures experienced by fish were closer to optimal; however, growth decreased for some fish. We found that salmon size and smolt date responded more strongly to warmer springs and summers than to warmer winters or increased variability. Fish in the least complex network grew faster and were ready to smolt earlier than fish in the more spatially complex network shapes in the contemporary thermal regime; patterns were similar but less clear in warmer thermal regimes. Our results demonstrate that network topology may influence how fish respond to thermal landscapes, and this information will be useful for incorporating a spatiotemporal context into conservation decisions that promote long-term viability of salmon in a changing climate.

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Spatial Identification of Tributary Impacts in River Networks

Cited by 20 publications

References 76 publications

Tributary connectivity, confluence aggradation and network biodiversity

Tributary connectivity, confluence aggradation and network biodiversity

Spatial disaggregation and aggregation procedures for characterizing fluvial features at the network-scale: Application to the Rhône basin (France)

Simulated juvenile salmon growth and phenology respond to altered thermal regimes and stream network shape

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