Coupling between hillslopes and channels in upland fluvial systems: implications for landscape sensitivity, illustrated from the Howgill Fells, northwest England

Harvey, Adrian

doi:10.1016/s0341-8162(00)00139-9

Cited by 294 publications

(255 citation statements)

References 21 publications

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“…These may result in reductions in recovery time for habitats and species between extreme events, changes in the distributions of landforms in response to altered patterns and rates of both erosion and deposition, and longer landform readjustment times to extreme events due to reactivation by subsequent events. Geomorphological processes and soils may become vulnerable to irreversible changes or changes in process regimes, so that an understanding of geomorphological sensitivity and the capacity of the system to absorb externally imposed stresses is a key consideration (Thomas, 2001;Werritty and Leys, 2001;Harvey, 2001;Burt et al, 2002;Church, 2002). In extreme cases, the frequency and speed of disruption may mean that habitat recovery may never be fully established, leading to a change in state.…”

Section: Geodiversity and Climate Changementioning

confidence: 99%

Engaging with geodiversity—why it matters

Gordon

Barron

Hansom

et al. 2012

Proceedings of the Geologists' Association

125

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The Conference, 'Engaging with Geodiversity -Why it Matters', December 2010, addressed the wider relevance of geodiversity in Scotland. A key challenge is to integrate geodiversity within existing policy relating to the way we work and live, and therefore to inform better the decisions we make about a sustainable future for our environment. This will require partnership working among the geoscience, geoconservation and voluntary sectors at both national and local levels, not only to demonstrate convincingly the economic, social, cultural and environmental values and benefits of geodiversity, but also to deliver real outcomes for both people and nature. The key drivers that provide particular opportunities, as well as challenges, for the integration of geodiversity are the development of an ecosystem approach and how society responds to climate change. Addressing these will be crucial from a geoconservation perspective to develop a wider understanding of the essential environmental role played by geodiversity and for the protection of key sites, both from a policy perspective in delivering economic, social and environmental benefits, and from an academic perspective in ensuring support for geoscience. The key message -that geodiversity matters -must be communicated strongly to the highest levels of government, among key interest groups and at a local community level.

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Section: Geodiversity and Climate Changementioning

confidence: 99%

Engaging with geodiversity—why it matters

Gordon

Barron

Hansom

et al. 2012

Proceedings of the Geologists' Association

125

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show abstract

“…Where river management restricts (a) lateral movement of the river and (b) transfer of sediment into floodplain storage, the channel bed becomes responsive (e.g. Schumm, 1979;Harvey, 2001;Hooke, 2003), and one response is aggradation. This will reduce channel conveyance and lead to the kinds of impacts described above in relation to flood risk.…”

Section: Combined Geometrical and Climate Changementioning

confidence: 99%

Interactions between sediment delivery, channel change, climate change and flood risk in a temperate upland environment

Lane¹,

Tayefi²,

Reid³

et al. 2006

Earth Surf Processes Landf

210

183

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This paper uses numerical simulation of flood inundation based on a coupled one-dimensionaltwo-dimensional treatment to explore the impacts upon flood extent of both long-term climate changes, predicted to the 2050s and 2080s, and short-term river channel changes in response to sediment delivery, for a temperate upland gravel-bed river. Results show that 16 months of measured in-channel sedimentation in an upland gravel-bed river cause about half of the increase in inundation extent that was simulated to arise from climate change. Consideration of the joint impacts of climate change and sedimentation emphasized the nonlinear nature of system response, and the possibly severe and synergistic effects that come from combined direct effects of climate change and sediment delivery. Such effects are likely to be exacerbated further as a result of the impacts of climate change upon coarse sediment delivery. In generic terms, these processes are commonly overlooked in flood risk mapping exercises and are likely to be important in any river system where there are high rates of sediment delivery and long-term transfer of sediment to floodplain storage (i.e. alluviation involving active channel aggradation and migration). Similarly, attempts to reduce channel migration through river bank stabilization are likely to exacerbate this process as without bank erosion, channel capacity cannot be maintained. Finally, many flood risk mapping studies rely upon calibration based upon combining contemporary bed surveys with historical flood outlines, and this will lead to underestimation of the magnitude and frequency of floodplain inundation in an aggrading system for a flood of a given magnitude.

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“…Such a multiscale framework was conceptualized by Heckmann and Schwanghart (2013), who clearly distinguished the coupling of processes and connectivity. On the one hand, geomorphic coupling is "the linkage of distinct landforms or landscape units by sediment transport" (Harvey, 2001); it refers to "elementary interactions at the relatively small scale" (Faulkner, 2008). On the other hand, "the degree of coupling, the combined effect of lateral (hillslope to channel) and longitudinal (from one river reach to another) linkages between system components, is termed (sediment) connectivity" (Heckmann and Schwanghart, 2013).…”

Section: Introductionmentioning

confidence: 99%

Assessment of structural sediment connectivity within catchments: insights from graph theory

Cossart

Fressard

2017

Earth Surf. Dynam.

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Abstract.To describe the sedimentary signal delivered at catchment outlets, many authors now refer to the concept of connectivity. In this framework, the sedimentary signal is seen as an emergent organization of local links and interactions. The challenge is thus to open the black boxes that remain within a sediment cascade, which requires both accurate geomorphic investigations in the field (reconstruction of sequences of geomorphic evolution, description of sediment pathways) and the development of tools dedicated to sediment cascade modeling. More precisely, the development of tools devoted to the study of connectivity in geomorphology is still in progress, although graph theory offers promising perspectives (Heckmann and Schwanghart, 2013). In this paper, graph theory is applied to abstract the network structure of sediment cascades, keeping only the nodes (sediment sources, sediment stores, outlet) and links (linkage by a transportation agent), represented as vertices and edges. From the description of the assemblages of sedimentary flows, we provide three main indices to explore how small-scale processes may result in significant broad-scale geomorphic patterns. The main hypothesis guiding this work is that the network structure dictates how sediment inputs from various sources interact at tributary junctions and finally at the outlet of a cascading system. First, we use the flow index to assess the potential contribution of each node to the sediment delivery at the outlet. Second, we measure the influence of each node regarding how it is accessible from both sediment sources and the outlet (using the Shimbel index). Third, we propose a new connectivity index named "Network Structural Connectivity index" (NSC) revealing whether the potential contribution of a node is lower or higher than expected from its location within the network. These indices are first computed for a conceptual sediment cascade network and then applied to a catchment located in the southern French Alps. We demonstrate that this index may be used to simulate sediment transfer and help in identifying the hotspots of geomorphic change. In the present case, we try to predict how a sediment cascade may be impacted by an edge disruption or a reconnection.

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Coupling between hillslopes and channels in upland fluvial systems: implications for landscape sensitivity, illustrated from the Howgill Fells, northwest England

Cited by 294 publications

References 21 publications

Engaging with geodiversity—why it matters

Engaging with geodiversity—why it matters

Interactions between sediment delivery, channel change, climate change and flood risk in a temperate upland environment

Assessment of structural sediment connectivity within catchments: insights from graph theory

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