Evolutionary geomorphology: thresholds and nonlinearity in landform response to environmental change

Phillips, Jonathan D.

doi:10.5194/hess-10-731-2006

Cited by 179 publications

(161 citation statements)

References 76 publications

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“…Identification of cause-effect relations in the context of threshold behaviour is made difficult as a result , especially when these are accompanied by structural or morphological changes as well (Newson, 1980;Newson and Newson, 2000;Phillips, 2004Phillips, , 2006Faulkner, 2008). Hence, threshold behaviour in hydrological and geoecosystems becomes much more difficult to detect, understand and predict in comparison to elementary threshold phenomena, which can be predicted on the basis of well observable dimensionless variables such as the Reynolds number.…”

Section: Introductionmentioning

confidence: 99%

Threshold behaviour in hydrological systems as (human) geo-ecosystems: manifestations, controls, implications

Zehe¹,

Sivapalan

2009

Hydrol. Earth Syst. Sci.

196

139

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Abstract. In this paper we review threshold behaviour in environmental systems, which are often associated with the onset of floods, contamination and erosion events, and other degenerative processes. Key objectives of this review are to a) suggest indicators for detecting threshold behavior, b) discuss their implications for predictability, c) distinguish different forms of threshold behavior and their underlying controls, and d) hypothesise on possible reasons for why threshold behaviour might occur. Threshold behaviour involves a fast qualitative change of either a single process or the response of a system. For elementary phenomena this switch occurs when boundary conditions (e.g., energy inputs) or system states as expressed by dimensionless quantities (e.g. the Reynolds number) exceed threshold values. Mixing, water movement or depletion of thermodynamic gradients becomes much more efficient as a result. Intermittency is a very good indicator for detecting event scale threshold behavior in hydrological systems. Predictability of intermittent processes/system responses is inherently low for combinations of systems states and/or boundary conditions that push the system close to a threshold. Post hoc identification of "cause-effect relations" to explain when the system became critical is inherently difficult because of our limited ability to perform observations under controlled identical experimental conditions. In this review, we distinguish three forms of threshold behavior. The first one is threshold behavior at the Correspondence to: E. Zehe (e.zehe@bv.tum.de) process level that is controlled by the interplay of local soil characteristics and states, vegetation and the rainfall forcing. Overland flow formation, particle detachment and preferential flow are examples of this. The second form of threshold behaviour is the response of systems of intermediate complexity -e.g., catchment runoff response and sediment yield -governed by the redistribution of water and sediments in space and time. These are controlled by the topological architecture of the catchments that interacts with system states and the boundary conditions. Crossing the response thresholds means to establish connectedness of surface or subsurface flow paths to the catchment outlet. Subsurface stormflow in humid areas, overland flow and erosion in semi-arid and arid areas are examples, and explain that crossing local process thresholds is necessary but not sufficient to trigger a system response threshold. The third form of threshold behaviour involves changes in the "architecture" of human geoecosystems, which experience various disturbances. As a result substantial change in hydrological functioning of a system is induced, when the disturbances exceed the resilience of the geo-ecosystem. We present examples from savannah ecosystems, humid agricultural systems, mining activities affecting rainfall runoff in forested areas, badlands formation in Spain, and the restoration of the Upper Rhine river basin as examples of this phenomenon. This fun...

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Section: Introductionmentioning

confidence: 99%

Threshold behaviour in hydrological systems as (human) geo-ecosystems: manifestations, controls, implications

Zehe¹,

Sivapalan

2009

Hydrol. Earth Syst. Sci.

196

139

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“…This effect is nonetheless expected because landslides typically change the surface morphology (Schuster and Highland 2003), the sediment or regolith properties (Chen 2009), the vegetation (Singh et al 2014) and the slope angle (van Westen et al 2006), which are all factors that change landslide susceptibility. If true, such importance of landslide history for landslides susceptibility would be a form of path dependency (a concept from complexity theory (Phillips 2006;Temme et al 2015))-indicating that the history of the landsliding process affects its future through one or more legacy effects. A likely reason for the lack of attention for quantifying the effect of earlier landslides on future landslides is that multi-temporal landslide inventories are very difficult to obtain (Atkinson and Massari 1998;Brenning 2005) and high-resolution multi-temporal datasets of intrinsic properties are virtually absent.…”

Section: Introductionmentioning

confidence: 99%

Do landslides follow landslides? Insights in path dependency from a multi-temporal landslide inventory

Samia¹,

Temme

Bregt³

et al. 2016

Landslides

143

109

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Landslides are a major category of natural disasters, causing loss of lives, livelihoods and property. The critical roles played by triggering (such as extreme rainfall and earthquakes), and intrinsic factors (such as slope steepness, soil properties and lithology) have previously successfully been recognized and quantified using a variety of qualitative, quantitative and hybrid methods in a wide range of study sites. However, available data typically do not allow to investigate the effect that earlier landslides have on intrinsic factors and hence on follow-up landslides. Therefore, existing methods cannot account for the potentially complex susceptibility changes caused by landslide events. In this study, we used a substantially different alternative approach to shed light on the potential effect of earlier landslides using a multitemporal dataset of landslide occurrence containing 17 time slices. Spatial overlap and the time interval between landslides play key roles in our work. We quantified the degree to which landslides preferentially occur in locations where landslides occurred previously, how long such an effect is noticeable, and how landslides are spatially associated over time. We also investigated whether overlap with previous landslides causes differences in landslide geometric properties. We found that overlap among landslides demonstrates a clear legacy effect (path dependency) that has influence on the landslide affected area. Landslides appear to cause greater susceptibility for follow-up landslides over a period of about 10 years. Follow-up landslides are on average larger and rounder than landslides that do not follow earlier slides. The effect of earlier landslides on follow-up landslides has implications for understanding of the landslides evolution and the assessment of landslide susceptibility.

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“…The influence of colluvium on terrace preservation highlights the importance of inherited catchment morphologies on subsequent fluvial development in these catchments (Phillips, 2006;Fryirs and Brierley, 2010). Vertical incision may occur gradually in association with annual flooding events in these rivers.…”

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confidence: 99%

Alluvial terrace preservation in the Wet Tropics, northeast Queensland, Australia

et al. 2015

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Alluvial terraces provide a record of aggradation and incision and are studied to understand river response to changes in climate, tectonic activity, sea level, and factors internal to the river system. Terraces form in all climatic regions and in a range of geomorphic settings; however, relatively few studies have been undertaken in tectonically stable settings in the tropics. The preservation of alluvial terraces in a valley is driven by lateral channel adjustments, vertical incision, aggradation, and channel stability, processes that can be further understood through examining catchment force-resistance frameworks. This study maps and classifies terraces using soil type, surface elevation, sedimentology, and optically stimulated luminescence dating across five tropical catchments in northeast Queensland, Australia. This allowed for the identification of two terraces across the study catchments (T1, T2).The T1 terrace was abandoned ~13.9 ka with its subsequent removal occurring until ~7.4 ka. Abandonment of the T2 terrace occurred ~4.9 ka with removal occurring until ~1.2 ka. Differences in the spatial preservation of these terraces were described using an index of terrace preservation (TPI). Assessments of terrace remnant configuration highlighted three main types of terraces: paired, unpaired, and disconnected, indicating the importance of different processes driving preservation.Regional-scale variability in TPI was not strongly correlated with catchment-scale surrogate variables for drivers of terrace erosion and resistance. However, catchmentspecific relationships between TPI and erosion-resistance variables were evident and are used here to explain the dominant processes driving preservation in these tropical settings. This study provides an important insight into terrace preservation in the tectonically stable, humid tropics and provides a framework for future research linking the timing of fluvial response to palaeoclimate change. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT IntroductionAlluvial terraces are topographic landforms that result from floodplain abandonment when a river incises, therefore providing records of river aggradation and incision (Leopold et al., 1964). Terraces have formed in all global regions and are commonly studied to understand how rivers have responded to the combined effects of changes in external controls including climate, tectonics, and sea level (Merritts et al., 1994;Macklin et al., 2002;Bridgland and Westaway, 2008) and in internal controls, such as catchment morphology (Coulthard et al., 2005) and reach-specific conditions (Houben, 2003).Terraces are generally identified in the landscape using a range of techniques including soil properties (see reviews in Birkeland, 1990;Huggett, 1998), topographic data (Pazzaglia and Gardner, 1993;Jones et al., 2007), aerial and satellite imagery (Litchfield and Berryman, 2005), with correlations further aided by sedimentology and dating (Stokes et al., 2012). The use of soil characteristics to classify terrace...

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Evolutionary geomorphology: thresholds and nonlinearity in landform response to environmental change

Cited by 179 publications

References 76 publications

Threshold behaviour in hydrological systems as (human) geo-ecosystems: manifestations, controls, implications

Threshold behaviour in hydrological systems as (human) geo-ecosystems: manifestations, controls, implications

Do landslides follow landslides? Insights in path dependency from a multi-temporal landslide inventory

Alluvial terrace preservation in the Wet Tropics, northeast Queensland, Australia

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