Impact of Changing Concavity Indices on Channel Steepness and Divide Migration Metrics

Gailleton, Boris; Mudd, Simon M.; Clubb, Fiona J.; Grieve, Stuart; Hurst, Martin D.

doi:10.1029/2020jf006060

Cited by 29 publications

(12 citation statements)

References 95 publications

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“…Although θ ref optimizations in individual catchments are, collectively, consistent with the regional analysis, they suggest substantial intercatchment variability. If true, then this would complicate topographic analyses and potentially confound efforts to evaluate relationships between erosion and topography ( 29 , 37 ).…”

Section: Resultsmentioning

confidence: 99%

“…River profile collinearity in χ-elevation plots (χ- z ) has become a popular method to determine optimal θ ref values from topography ( 34 , 36 , 37 ). This method leverages the SPM prediction that, provided θ ref is set appropriately, the χ-transform linearizes river profiles adjusted to uniform conditions with slopes equal to k sn ( 34 ).…”

Section: Introductionmentioning

confidence: 99%

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Isolating climatic, tectonic, and lithologic controls on mountain landscape evolution

2023

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Establishing that climate exerts an important general influence on topography in tectonically active settings has proven an elusive goal. Here, we show that climates ranging from arid to humid consistently influence fluvial erosional efficiency and thus topography, and this effect is captured by a simple metric that combines channel steepness and mean annual rainfall, k snQ . Accounting for spatial rainfall variability additionally increases the sensitivity of channel steepness to lithologic and tectonic controls on topography, enhancing predictions of erosion and rock uplift rates, and supports the common assumption of a reference concavity near 0.5. In contrast, the standard channel steepness metric, k sn , intrinsically assumes that climate is uniform. Consequently, its use where rainfall varies spatially undermines efforts to distinguish climate from tectonic and lithologic effects, can bias reference concavity estimates, and may ultimately lead to false impressions about rock uplift patterns and other environmental influences. Capturing climate is therefore a precondition to understanding mountain landscape evolution.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Isolating climatic, tectonic, and lithologic controls on mountain landscape evolution

2023

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“…While varying m and n, we maintain their ratio constant at 0.45, a widely applied average channel concavity (e.g., Wobus et al, 2006;Harel et al, 2016), and in line with the global average of 0.42 reported by Gailleton et al (2021).…”

Section: Methodsmentioning

confidence: 89%

“…At more restricted scales, erosion rates based on cosmogenic nuclides (e.g., 10 Be) show a modest exponential correlation with catchment-averaged slope, as does normalised steepness in stream profiles (Portenga and Bierman, 2011;Harel et al, 2016). Nevertheless, it is widely observed that steepness and stream power parameters are subject to notable variation wherever climate and/or lithology differ (Harel et al, 2016;Gailleton et al, 2021;Marder and Gallen, 2022), and a robust analysis must accommodate such interactions.…”

Section: Introductionmentioning

confidence: 99%

Optimising global landscape evolution models with ¹⁰Be

Ruetenik

Jansen²,

Val³

et al. 2022

Preprint

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Abstract. By simulating erosion and deposition, landscape evolution models offer powerful insights to Earth surface processes and dynamics. These models are typically constructed from parameters describing drainage area (m), slope (n), substrate erodibility (K), hillslope diffusion (D), and a critical drainage area (Ac) that signifies the downslope transition from hillslope diffusion to advective fluvial processes. In spite of the widespread success of such models, the parameter values have high degrees of uncertainty mainly because the advection and diffusion equations amalgamate physical processes and material properties that span widely differing spatial and temporal scales. Here, we use a global catalogue of catchment-averaged cosmogenic 10Be-derived erosion (denudation) rates with the aim to optimise a set of landscape evolution models via a Monte Carlo based parameter search. We consider three model scenarios: advection-only, diffusion-only, and an advection-diffusion hybrid. In each case, we search for a parameter set that best approximates erosion rates at the global scale, and we directly compare erosion rates from the modelled scenarios with those derived from 10Be data. Optimised ranges can be defined for many LEM parameters at the global scale. In the absence of diffusion, n ~ 1.3, and with increasing diffusivity the optimal n increases linearly to a global maximum of n ~ 2. Meanwhile we find that the diffusion-only model somewhat outperforms the advection-only model and is optimised when concavity is raised to a power of 2. With these examples, we suggest that our approach provides baseline parameter estimates for large-scale studies spanning long timescales and diverse landscape properties. Moreover, our direct comparison of model-predicted versus observed erosion rates is preferable to methods that rely upon catchment-scale averaging or amalgamation of topographic metrics. We also seek to optimise K and D parameters in landscape evolution models with respect to precipitation and substrate lithology. These optimised models allow us to effectively control for topography and target specifically the relationship between erosion rate and precipitation. All models suggest a positive correlation between K or D and precipitation > 1500 mm yr–1, plus a local maximum at ~ 300 mm yr–1, which is compatible with the long-standing hypothesis that semi-arid environments are among the most erodible.

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“…At the catchment-scale, diversity in river morphology has been observed in the Philippines with eight distinct River Styles (geomorphic river types) identified in the 586 km 2 Bislak catchment [40]. Spatial heterogeneity in the concavity index, used to indicate how quickly river channel gradient declines downstream, has been shown across the Cordillera Central of Ilocos Norte [69]. Physical attributes of the landscape impose boundary conditions that control hydromorphological attributes in river systems; the heterogeneity in morphometric and topographic characteristics are likely explained by the diverse geologic, tectonic and climatic settings across the analysed catchments.…”

Section: Diversity and Distinctiveness Of Stream Network And River Ca...mentioning

confidence: 99%

National-scale geodatabase of catchment characteristics in the Philippines for river management applications

Boothroyd

Williams²,

Hoey³

et al. 2023

PLoS ONE

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Quantitative descriptions of stream network and river catchment characteristics provide valuable context for enabling geomorphologically-informed sustainable river management. For countries where high-quality topographic data are available, there are opportunities to enable open access availability of baseline products from systematic assessment of morphometric and topographic characteristics. In this study, we present a national-scale assessment of fundamental topographic characteristics of Philippine river systems. We applied a consistent workflow using TopoToolbox V2 to delineate stream networks and river catchments using a nationwide digital elevation model (DEM) acquired in 2013 and generated through airborne Interferometric Synthetic Aperture Radar (IfSAR). We assessed morphometric and topographic characteristics for 128 medium- to large-sized catchments (catchment area > 250 km2) and organised the results in a national-scale geodatabase. The dataset realises the potential of topographic data as part of river management applications, by enabling variations in hydromorphology to be characterised and contextualised. The dataset is used to reveal the diversity of stream networks and river catchments in the Philippines. Catchments have a continuum of shapes (Gravelius compactness coefficient ranges from 1.05 to 3.29) with drainage densities that range from 0.65 to 1.23 km/km2. Average catchment slope ranges from 3.1 to 28.1° and average stream slope varies by more than an order of magnitude from 0.004 to 0.107 m/m. Inter-catchment analyses show the distinctive topographic signatures of adjacent river catchments; examples from NW Luzon highlight topographic similarity between catchments whereas examples from Panay Island shown marked topographic differences. These contrasts underline the importance of using place-based analyses for sustainable river management applications. By designing an interactive ArcGIS web-application to display the national-scale geodatabase, we improve data accessibility and enable users to freely access, explore and download the data (https://glasgow-uni.maps.arcgis.com/apps/webappviewer/index.html?id=a88b9ca0919f4400881eab4a26370cee). The national-scale geodatabase provides a baseline understanding of fundamental topographic characteristics in support of varied geomorphological, hydrological and geohazard susceptibility applications.

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Impact of Changing Concavity Indices on Channel Steepness and Divide Migration Metrics

Abstract: Impact of changing concavity indices on channel steepness and divide migration metrics

Cited by 29 publications

References 95 publications

Isolating climatic, tectonic, and lithologic controls on mountain landscape evolution

Isolating climatic, tectonic, and lithologic controls on mountain landscape evolution

Optimising global landscape evolution models with ¹⁰Be

National-scale geodatabase of catchment characteristics in the Philippines for river management applications

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Impact of Changing Concavity Indices on Channel Steepness and Divide Migration Metrics

Abstract: Impact of changing concavity indices on channel steepness and divide migration metrics

Cited by 29 publications

References 95 publications

Isolating climatic, tectonic, and lithologic controls on mountain landscape evolution

Isolating climatic, tectonic, and lithologic controls on mountain landscape evolution

Optimising global landscape evolution models with 10Be

National-scale geodatabase of catchment characteristics in the Philippines for river management applications

Contact Info

Product

Resources

About

Optimising global landscape evolution models with ¹⁰Be