Systematic variation of bedrock channel gradients in the central Oregon Coast Range: implications for rock uplift and shallow landsliding

Kobor, Jeremiah S.; Roering, J. J.

doi:10.1016/j.geomorph.2004.02.013

Cited by 77 publications

(63 citation statements)

References 51 publications

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“…Numerous studies infer landscape dynamics from channel slope-area analyses; in particular, the positive correlation between channel steepness index and rock uplift rate allows spatial patterns of tectonics to be investigated across large areas (e.g., Snyder et al 2000;Kobor and Roering 2004). However, as the steepness index is also strongly influenced by erosion resistance and precipitation patterns, a simplification that excludes lithological variation is commonly adopted for the sake of exploring rock uplift.…”

Section: Methods and Approachmentioning

confidence: 99%

Scale Dependence of Lithological Control on Topography: Bedrock Channel Geometry and Catchment Morphometry in Western Scotland

Jansen¹,

Codilean²,

Bishop³

et al. 2010

The Journal of Geology

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We propose that a scale-dependent topographic signature of erodibility arises due to fiuvial and glacial erosion acting on different parts of the landscape at different times. For 14 catchments in western Scotland, we define three levels of substrate erodibility in order of decreasing resistance: quartzite rocks, nonquartzite rocks, and zones of fault-related fracture. Then, using digital topographic and planimetric data coupled with field measurements, we identify regression-based scaling relationships between substrate erodibility and morphometric parameters at two spatial scales. Catchment-scale morphometry shows a weak to variable relationship with substrate metrics overall. Erodibility can be inferred from catchment steepness indices (i.e., channel steepness index and relief ratio), but the existence of multiple exceptions could confound a more general application of this approach. Nonetheless, major valley troughs trace fault zones and nonquartzite rocks, leaving much of the higher arid steeper ground formed in quartzite. At the reach scale, bedrock channel slope is far more sensitive to substrate erodibility than is channel width. Quartzite outcrops steepen bedrock channels by a factor of 1.5-6.0, and in terms of unit stream power, channels increase their erosional capacity by a factor of 2.7-3.5. Yet only 4%-13% of this increase is due to channel narrowing. Based on a large data set of bedrock channel width (n = 5825) from four rivers, we find that width scales with drainage area (in m²) as W = 0.01A0.28. Our results are consistent with the view that width-area scaling is similar in all single-thread rivers subject to transport-limited conditions but that for increasingly sediment supply-limited settings, erosional thresholds at the channel boundary are the key determinants of bedrock channel width. A B S T R A C TWe propose that a scale-dependent topographic signature of erodibility arises due to fluvial and glacial erosion acting on different parts of the landscape at different times. For 14 catchments in western Scotland, we define three levels of substrate erodibility in order of decreasing resistance: quartzite rocks, nonquartzite rocks, and zones of fault-related fracture. Then, using digital topographic and planimetric data coupled with field measurements, we identify regressionbased scaling relationships between substrate erodibility and morphometric parameters at two spatial scales. Catchment-scale morphometry shows a weak to variable relationship with substrate metrics overall. Erodibility can be inferred from catchment steepness indices (i.e., channel steepness index and relief ratio), but the existence of multiple exceptions could confound a more general application of this approach. Nonetheless, major valley troughs trace fault zones and nonquartzite rocks, leaving much of the higher and steeper ground formed in quartzite. At the reach scale, bedrock channel slope is far more sensitive to substrate erodibility than is channel width. Quartzite outcrops steepen bedrock channels by a ...

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Section: Methods and Approachmentioning

confidence: 99%

Scale Dependence of Lithological Control on Topography: Bedrock Channel Geometry and Catchment Morphometry in Western Scotland

Jansen¹,

Codilean²,

Bishop³

et al. 2010

The Journal of Geology

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“…Kobor et al (2004), for example, carried out a slope-area analysis for several small sub-basins in the central Oregon Coast Range. This analysis was very useful in determining the parameters in these small sub-basins but not for inflection analysis of the main streams.…”

Section: Advantages and Limitations Of Slk Mapsmentioning

confidence: 99%

Spatial analysis of stream power using GIS: SLk anomaly maps

Pérez-Peña

Azañón

Azor

et al. 2008

Earth Surf Processes Landf

139

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The stream length-gradient index (SL) shows the variation in stream power along river reaches. This index is very sensitive to changes in channel slope, thus allowing the evaluation of recent tectonic activity and/or rock resistance. Nevertheless, the comparison of SL values from rivers of different length is biased due to the manner in which the index is formulated, thus making correlations of SL anomalies along different rivers difficult. Therefore, when undertaking a comparison of SL values of rivers of different lengths, a normalization factor must be used. The graded river gradient (K ) has already been used in some studies to normalize the SL index. In this work, we explore the relationships between the graded river gradient (K), the SL index and the stream power, proposing the use of a re-named SLk index, which enables the comparison of variable-length rivers, as well as the drawing of SLk anomaly maps. We present here a GIS-based procedure to generate SLk maps and to identify SLk anomalies. In order to verify the advantages of this methodology, we compared an SLk map of the NE border of the Granada basin with both simple river profileknickpoint identification and with an SL map. The results show that the SLk map supplies good results with defined anomalies and suitably reflects the main tectonic and lithological features of the study area.

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“…Ashley et al (1988) and Itakura and Ikeda (1997) studied meandering bedrock channel. Relation between basin area and bedrock channel width was studied by Montgomery and Gran (2001) while Kobor and Roering (2004) performed study on basin area and channel slope of rivers over rocks. Miller (1991), Wohl et al (1994), Seidl et al (1996), Righter (1997), Seidl (1997, 1998), Wohl andIkeda (1998), Wohl (2000), Wohl andMerritt (2001), wohl andAchyuthan (2002) contributed valuable work on knick points.…”

Section: Introductionmentioning

confidence: 99%

Hydraulic Parameters and Morphometric Variables Interactions in Bedrock Channel

Biswas¹,

Das²

2016

Quaestiones Geographicae

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Biswas B., das B. C., 2016. Hydraulic parameters and morphometric variables interactions in bedrock channel. Quaestiones Geographicae 35(3), Bogucki Wydawnictwo Naukowe, Poznań, pp. 75-88, 12 figs.aBstraCt: Present study is on the interdependent nature of hydraulic parameters and morphometric variables of a bedrock river. In this study, using dumpy level, GPS, satellite images and some mathematical equations a data set on hydraulics and morphometric variables of a bedrock channel, named Bhatajhor, of eastern India was generated. That data set was used to (1) find out impulse-response relations between hydraulic variables (2) find out relations between morphometric variables and (3) find out relations between hydraulic and morphometric variables. Seven equations (5-11) were formulated based on this empirical study to the end. The seven empirical relations, most of which include only two variables, involve channel cross-section dimensions (area, width, mean depth, maximum depth, width/ depth ratio, hydraulic radius), slope and hydraulic variables (velocity, kinetic energy, stream power, Manning's n factor, Chezy's C factor and shear stress). Observation shows relatively higher coefficient of determination (R2) between variables like velocity and Manning's n factor (0.67), velocity and Chezy's C factor (0.67), slope and τ (0.89), w/d ratio and hydraulic radius (0.53), slope and w/d ratio (0.50).

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Systematic variation of bedrock channel gradients in the central Oregon Coast Range: implications for rock uplift and shallow landsliding

Cited by 77 publications

References 51 publications

Scale Dependence of Lithological Control on Topography: Bedrock Channel Geometry and Catchment Morphometry in Western Scotland

Scale Dependence of Lithological Control on Topography: Bedrock Channel Geometry and Catchment Morphometry in Western Scotland

Spatial analysis of stream power using GIS: SLk anomaly maps

Hydraulic Parameters and Morphometric Variables Interactions in Bedrock Channel

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