Time, space, and causality in geomorphology

Schumm, S. A.; Lichty, Robert W.

doi:10.2475/ajs.263.2.110

Cited by 742 publications

(416 citation statements)

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“…Our findings suggest that a high accuracy level is more suitable for small-scale models, while an equivalent model may be preferred for global analyses. This seems to agree with the observation by Schumm and Lichty (1965) that a change in space dimension (i.e. model extent) requires a different model description.…”

Section: Discussionsupporting

confidence: 92%

“…The role of scale in geomorphology has been massively debated (Warke and McKinley, 2011): some considered the spatial scale (Zhang et al, 2011;Kerry and Oliver, 2011;Yan et al, 2011), some addressed the temporal scale (Smith, 1996;Viles, 2001;Dymond and De Rose, 2011) and others focused on how to upscale observations from microscale to macroscale (Viles and Moses, 1998;Viles, 2001;Zengchao et al, 2009). In terms of the scale choice, we acknowledge the statement by Schumm and Lichty (1965): "As the dimensions of time and space change, cause-effect relationships may be obscured or even reversed, and the system itself may be described differently", and that by Bachmann et al (2006): "a single landslide […] evolution will depend on what is happening at larger but also at smaller scales". Accordingly, this paper focuses on the effect of the spatial scale and data accuracy on landslide modeling for failure forecasting.…”

Section: Introductionmentioning

confidence: 99%

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The role of the spatial scale and data accuracy on deep-seated gravitational slope deformation modeling: The Ronco landslide, Italy

et al. 2016

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In recent decades numerical models have been developed and extensively used for landslide hazard and risk assessment. The reliability of the outcomes of these numerical simulations must be evaluated carefully as it mainly depends on the soundness of the physical model of the landslide that in turn often requires the integration of several surface and subsurface surveys in order to achieve a satisfactory spatial resolution. Merging diverse sources of data may be particularly complex for large landslides, because of intrinsic heterogeneity and possible great data uncertainty. In this paper, we assess the spatial scale and data accuracy required for effective numerical landslide modeling. We focus on two particular aspects: the model extent and the accuracy of input datasets. The Ronco landslide, a deep-seated gravitational slope deformation (DSGSD) located in the North of Italy, was used as a test-bed. Geological, geomorphological and geophysical data were combined and, as a result, eight models with different spatial scales and data accuracies were obtained. The models were used to run a back analysis of an event in 2002, during which part of the slope moved after intense rainfalls. The results point to the key role of a proper geomorphological zonation to properly set the model extent. The accuracy level of the input datasets should also be tuned. We suggest applying the approach presented here to other DSGSDs with different geological and geomorphological settings to test the reliability of our findings.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

The role of the spatial scale and data accuracy on deep-seated gravitational slope deformation modeling: The Ronco landslide, Italy

et al. 2016

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“…In this study, rills were incised in highly erodible soils, so adjustment time was very short. Using Schumm and Lichty's (1965) concepts, rill dynamics during a single storm appear to represent graded time, during which self-regulation is important, and system components may be graded or in dynamic equilibrium. At any time during the adjustment, the rill may exhibit equilibrium, but this changes over time (see e.g.…”

Section: Flow Energy and Channel Adjustments In Rills 141mentioning

confidence: 99%

Flow energy and channel adjustments in rills developed in loamy sand and sandy loam soils

Stefanovic

Bryan

2008

Earth Surf Processes Landf

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The storms usually associated with rill development in nature are seldom prolonged, so development is often interrupted by interstorm disturbances, e.g. weathering or tillage. In laboratory simulated rainfall experiments, active rill development can be prolonged, and under these conditions typically passes through a period of intense incision, channel extension and bifurcation before reaching quasi-stable conditions in which little form change occurs. This paper presents laboratory experiments with coarse textured soils under simulated rainfall which show how channel adjustment processes contribute to the evolution of quasi-stability.Newly incised rills were stabilized for detailed study of links between rill configuration and flow energy. On a loamy sand, adjustment towards equilibrium occurred due to channel widening and meandering, whereas on a sandy loam, mobile knickpoints and chutes, pulsations in flow width and flow depth and changes in stream power and sediment discharge occurred as the channel adjusted towards equilibrium. The tendency of rill systems towards quasi-stability is shown by changes in stream power values which show short-lived minima. Differences in energy dissipation in stabilized rills indicate that minimization of energy dissipation was reached locally between knickpoints and at the downstream ends of rills. In the absence of energy gradients in knickpoints and chutes, stabilized rill sections tended toward equilibrium by establishing uniform energy expenditure. The study confirmed that energy dissipation increased with flow aspect ratio. In stabilized rills, flow acceleration reduced energy dissipation on the loamy sand but not on the sandy loam. On both soils flow deceleration tended to increase energy dissipation.Understanding how rill systems evolve towards stability is essential in order to predict how interruptions between storms may affect long-term rill dynamics. This is essential if event-based physical models are to become effective in predicting sediment transport on rilled hillslopes under changing weather and climatic conditions.

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“…As pointed out by Schumm and Lichty (1965) Evaluations of interactions (past and present) between climate and the earth's surface require that processes be analyzed over time scales that are appropriate to the methodology and degree of accuracy available. For example, the impact of climatic change on geologic processes could be evaluated for the following time periods, using the following methods: 1.…”

Section: Investigating Climate Changementioning

confidence: 99%