The influence of lithology on channel geometry and bed sediment organization in mountainous hillslope‐coupled streams

Fratkin, Michael M.; Segura, Catalina; Bywater‐Reyes, Sharon

doi:10.1002/esp.4885

Cited by 10 publications

(8 citation statements)

References 95 publications

(178 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Grain size data come from a mix of published and new surveys. For the Elder Creek (NCCR) and OCR sites, we used existing bed sediment grain size surveys (Fratkin et al, 2020; Scheingross et al, 2013). Grain size data from the SGM and NSJM (Neely & DiBiase, 2020) are described in more detail in Section 4.2.4.…”

Section: Compilation Of Headwater Channel Morphologies In Steep Lands...mentioning

confidence: 99%

Sediment controls on the transition from debris flow to fluvial channels in steep mountain ranges

Neely

DiBiase

2023

Earth Surf Processes Landf

View full text Add to dashboard Cite

Steep channel networks commonly show a transition from constant-gradient colluvial channels associated with debris flow activity to concave-up fluvial channels downstream. The trade-off between debris flow and fluvial erosion in steep channels remains unclear, which obscures connections among topography, tectonics, and climate in steep landscapes. Here, we analyze steep debris-flow-prone channels across the western United States and observe: (1) similar maximum channel gradients across a range of catchment erosion rates and geologic settings; and (2) lengthening colluvial channels with coarsening sediment cover. Following this compilation, we hypothesize that steep channel gradients are controlled by two competing thresholds of motion for bed-sediment cover: bed failure by mass-wasting and fluvial entrainment. We use downstream patterns in discharge, channel geometry, and sediment size to calculate discharges needed to mobilize sediment cover by both mechanisms across channels in the San Gabriel Mountains (SGM) and northern San Jacinto Mountains (NSJM) in southern California. Across steep colluvial channels in both landscapes, decadal discharges are below fluvial entrainment thresholds but above mass-wasting entrainment thresholds for D 50 (median) sediment sizes, consistent with recent debris flows captured by repeat imagery. Colluvial channel gradient is similar despite > 3Â contrasts in surface sediment grain size. In concave-up fluvial channels downstream, decadal discharges exceed fluvial entrainment thresholds, and mass-wasting is not predicted on lower gradients. In both landscapes, fluvial channels steepen downstream compared to gradients needed to mobilize sediment cover, which we interpret to reflect downstream increases in sediment flux. Coarser sediment supply in the NSJM than the SGM increases fluvial entrainment thresholds, which increases total channel relief in the NSJM by (1) lengthening colluvial channels shaped by debris flows and (2) increasing fluvial channel gradients. Our compilation and downstream analysis show how differing sensitivity of fluvial and debris flow processes to sediment grain size impacts the relative relief of colluvial and fluvial regimes in headwater channel networks.

show abstract

Section: Compilation Of Headwater Channel Morphologies In Steep Lands...mentioning

confidence: 99%

Sediment controls on the transition from debris flow to fluvial channels in steep mountain ranges

Neely

DiBiase

2023

Earth Surf Processes Landf

View full text Add to dashboard Cite

show abstract

“…Increased sediment flux from earthflows appears to be mostly fine sediment; grain size surveys indicate high amounts of fine sediment and moderate coarse sediment loads in the North Fork tributaries with no significant difference between tributaries draining Teanaway and lower Roslyn formations, despite a rock strength difference between the basalt and friable sandstone (NFTWA, 1996). In a similar sandstone formation, Fratkin et al (2020) found significant variation in surface and subsurface grain size when compared with adjacent tributaries draining basalt; most bedload in their study area was delivered by debris flows and landslides. However, earthflows tend to incorporate highly weathered material and regolith; in the Eel River, 90 % of earthflow colluvium is smaller than 76 mm (Mackey and Roering, 2011).…”

Section: Landscape Disturbancementioning

confidence: 82%

Controls on earthflow formation in the Teanaway River basin, central Washington State, USA

Schanz

Colee

2022

Earth Surf. Dynam.

View full text Add to dashboard Cite

Abstract. Earthflows create landscape heterogeneity, increase local erosion rates, and heighten sediment loads in streams. These slow moving and fine-grained mass movements make up much of the Holocene erosion in the Teanaway River basin, central Cascade Range, Washington State, yet controls on earthflow activity and the resulting topographic impacts are unquantified. We mapped earthflows based on morphologic characteristics and relatively dated earthflow activity using a flow directional surface roughness metric called MADstd. The relative MADstd activity is supported by six radiocarbon ages, three lake sedimentation ages, and 16 cross-cutting relationships, indicating that MADstd is a useful tool to identify and relatively date earthflow activity, especially in heavily vegetated regions. Nearly all of the mapped earthflows are in the Teanaway and lower Roslyn formations, which comprise just 32.7 % of the study area. Earthflow aspect follows bedding planes in these units, demonstrating a strong lithologic control on earthflow location. Based on absolute ages and MADstd distributions, a quarter of the earthflows in the Teanaway Basin were active in the last few hundred years; the timing coincides with deforestation and increased land use in the Teanaway. Major tributaries initiate in earthflows and valley width is altered by earthflows that create wide valleys upstream and narrow constrictions within the earthflow zone. Although direct sediment delivery from earthflows brings fine sediment to the channel, stream power is sufficient to readily transport fines downstream. Based on our findings, over the Holocene – and particularly in the last few hundred years – lithologic-controlled earthflow erosion in the Teanaway basin has altered valley bottom connectivity and increased delivery of fine sediments to tributary channels.

show abstract

“…The Scamander catchment offers a unique opportunity to investigate the influences of lithology on river channel form, with two sub‐catchments of similar size and differing geology, of far larger scale relative to similar comparisons (Fratkin et al, 2020; Johnson & Finnegan, 2015). GIS analysis of geological distributions showed that granite makes up 45% of the area of the upper Scamander and dominates the northern upper half of this sub‐catchment, allowing weathering products of quartz sand to influence downstream channels.…”

Section: Discussionmentioning

confidence: 99%

“…Comparison of catchments with many similar attributes but a few that are variable can give insights on bedrock controls of landscape evolution (DiBiase et al, 2018). Two gravel‐bed streams with contrasting lithology (basalt and sandstone) in Oregon showed varied channel shapes, slopes and riffle grain sizes, indicating that lithologic control on channel adjustment is driven by differences in rock competence (Fratkin et al, 2020). Two bedrock‐controlled streams in California showed very different planforms, one in sandstone being straight, and in mudstone being sinuous (Johnson & Finnegan, 2015), largely attributed to rock disintegration characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…Two bedrock‐controlled streams in California showed very different planforms, one in sandstone being straight, and in mudstone being sinuous (Johnson & Finnegan, 2015), largely attributed to rock disintegration characteristics. The influence of lithology on channel form and adjustment and sediment type remains poorly understood (Fratkin et al, 2020; Shobe et al, 2021). The role of lithology in bedrock river morphology remains a poorly developed concept in fluvial geomorphology research.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Lithological controls influence river form in contrasting sub‐catchments: The Scamander and Avenue Rivers, Tasmania

Fearman

Ellison

2023

River Research & Apps

View full text Add to dashboard Cite

Bedrock influence on river channel form is difficult to assess, with many catchments dominated by glacial erosion and with blanketing sediments from both pluvial and fluvial sources. The Scamander catchment in Tasmania lacks glacial history and features two bedrock-confined sub-catchments of similar area and maximum flow length, but one dominated by Mathinna Group sedimentary rocks, and the other with large areas in granite lithology. Lithology types, stream network parameters and near stream slope angles were analysed using geographical information systems, and results of stream cross sections, channel form and planforms were compared for each lithology. Results showed that granite features low gradient, shallow streams with channel slope cross sections of <10 . Granite channels are irregular and dominated by large boulders that create channel roughness and resist incision. Weathering products of coarse quartz sand provide anchorages for in-channel vegetation. By contrast, sedimentary Mathinna Group rocks feature steeply incised trough-like channels, with near-channel hillslope gradients mostly between 30 and 50 . Rectangular blocks disintegrate to gravel cobbles on the channel bed, providing poor anchorage for vegetation. Mathinna lithology influences steep, low roughness channels, and stable, incised recurved meanders formed by river interaction with vertical layers of resistant rock.The resistant bedrock lithology is demonstrated in this study to influence varied river planforms, near-channel slope gradients, channel sediments and cross sections.bedrock rivers, Mathinna Group rocks, river catchment, river channel, river geomorphology, river planform, Strahler stream order | INTRODUCTIONBedrock rivers are an outstanding feature within geodiversity, where river channels feature exposed rock with little sediment (Gomez-Heras et al., 2019). Lithological controls set the boundary conditions in which rivers operate, providing the resisting framework on which exogenic processes influence river character and behaviour (Brierley, 2010;Schumm, 1977;Wohl & Ikeda, 1997). Tectonic uplift, climate change and base level fall can increase the transporting power of water relative to the available sediment supply, causing incision into the channel bed (Simon & Rinaldi, 2006;Wohl & Ikeda, 1998;Yanites, 2018). River erosion patterns are strongly influenced by bedrock (Wohl & Ikeda, 1998), also influencing river response to tectonic forcing (Shobe et al., 2021).

show abstract

The influence of lithology on channel geometry and bed sediment organization in mountainous hillslope‐coupled streams

Abstract: Lithology, channel geometry and bed sediment in mountainous streamsThe influence of lithology on channel geometry and bed sediment organization in mountainous hillslope-coupled streams Running Head: Lithology, channel geometry and bed sediment in mountainous streams

Cited by 10 publications

References 95 publications

Sediment controls on the transition from debris flow to fluvial channels in steep mountain ranges

Sediment controls on the transition from debris flow to fluvial channels in steep mountain ranges

Controls on earthflow formation in the Teanaway River basin, central Washington State, USA

Lithological controls influence river form in contrasting sub‐catchments: The Scamander and Avenue Rivers, Tasmania

Contact Info

Product

Resources

About