Zeitschrift für Geomorphologie, Supplementary Issues, 2012
ABSTRACT Projected climate change in cold environments is expected to alter melt-season duration ... more ABSTRACT Projected climate change in cold environments is expected to alter melt-season duration and intensity, along with the number of extreme rainfall events, total annual precipitation and the balance between snowfall and rainfall. In addition, changes to the thermal balance are expected to reduce the extent of permafrost and seasonal ground frost and increase active layer depth. These effects will change surface environments in cold climate environments and alter the flfl uxes of sediments, nutrients and solutes, but the absence of data and coordinated quantitative analysis to understand the sensitivity of the surface environment are acute in cold environments. The I.A.G/A.I.G. SEDIBUD (Sediment Budgets in Cold Environments) Programme, building on the ESF SEDIFLUX (Sedimentary Source-to-Sink-Fluxes in Cold Environments) Network, has been formed to address this key knowledge gap. Coordinated efforts are carried out to quantify, compare and model sedimentary flfl uxes and budgets in 38 selected SEDIBUD Key Test Sites (cold environment catchments) worldwide.
Geomorphological Processes and Landscape Change, 2001
While the outlines of the lowlands are touched with the instability that marks everything human, ... more While the outlines of the lowlands are touched with the instability that marks everything human, these far heights seem to remain impassive and unaffected, as if the hand of time had passed them by. Hence the everlasting hills have ever been favourite emblems, not only ...
This study estimates the complete carbon budget of an 11.4 km2 peat-covered catchment in Northern... more This study estimates the complete carbon budget of an 11.4 km2 peat-covered catchment in Northern England. The budget considers both fluvial and gaseous carbon fluxes and includes estimates of particulate organic carbon (POC); dissolved organic carbon (DOC); excess dissolved CO2; release of methane (CH4); net ecosystem respiration of CO2; and uptake of CO2 by primary productivity. All components except CH4 were measured directly in the catchment and annual carbon budgets were calculated for the catchment between 1993 and 2005 using both extrapolation and interpolation methods. The study shows that: Over the 13 year study period the total carbon balance varied between a net sink of − 20 to − 91 Mg C/km2/yr. The biggest component of this budget is the uptake of carbon by primary productivity (− 178 Mg C/km2/yr) and in most years the second largest component is the loss of DOC from the peat profile (+ 39 Mg C/km2/yr). Direct exchanges of C with the atmosphere average − 89 Mg C/km2/yr in the catchment. Extrapolating the general findings of the carbon budget across all UK peatlands results in an approximate carbon balance of − 1.2 Tg C/yr (± 0.4 Pg C/yr) which is larger than previously reported values. Carbon budgets should always be reported with a clear statement of the techniques used and errors involved as this is significant when comparing results across studies.
Abstract This paper describes and analyses the structure and deposits of a large UK peat slide, l... more Abstract This paper describes and analyses the structure and deposits of a large UK peat slide, located at Hart Hope in the North Pennines, northern England. This particular failure is unusual in that it occurred in the winter (February, 1995) and shows excellent preservation ...
... uncommon (Dykes and Kirk, 2006), but they have been reported at upland locations from Dartmoo... more ... uncommon (Dykes and Kirk, 2006), but they have been reported at upland locations from Dartmoor, SW England (Vancouver, 1808), to Shetland, N Scotland (Veyret and ... On other parts of the summit ridge and adjacent slopes peat extraction by tine-cutting was attempted ...
Published accounts of peat mass movements throughout the last 500 years reveal common characteris... more Published accounts of peat mass movements throughout the last 500 years reveal common characteristics among the failures; however, there has been no consistency in the terminology used to describe them. Given the apparently increasing frequency of peat failures in the British Isles and the possibility of more peat failures elsewhere in the world as a consequence of climate change, there is a need for a specific classification scheme. This paper proposes a scheme that uses clearly defined terms that can be readily applied and reliably used to understand and assess future hazards from peat mass movements. The paper begins with a general definition of what should constitute a ‘peat failure’, then presents a precisely defined classification scheme for peat landslides (i.e. excluding creep), using type of peat deposit and failure morphology as the key criteria. The new scheme for peat failures is discussed in the context of existing landslide classification systems. Definitions are provided for bog bursts (flow failure of raised bogs), bogflows (flow failure of blanket bogs), bog slides (shear failure and sliding of blanket bogs), peat slides (shear failure at peat–mineral interface in blanket bogs), peaty-debris slides (shear failure within mineral substrate beneath blanket bogs) and peat flows (natural failures of other types of peat deposits including flow failure caused by head-loading). Some practical problems of classifying peat failures are discussed.
Recent technological developments in the application of the Global Positioning System (GPS) offer... more Recent technological developments in the application of the Global Positioning System (GPS) offer the prospect of rapidly mapping difficult terrain and quantifying temporal and spatial dynamics of erosion and sedimentation. While many developments in GPS have been considered from the viewpoint of geodesy, their versatility in geomorphological situations has had limited attention. In particular, the improved accuracy and reduced costs of some GPS systems makes them attractive for many mapping applications. Differential GPS allows the logging of position of a mobile receiver relative to a control station. In difficult terrain, such as uplands, the location and distribution of survey points by GPS is much more efficient than conventional survey techniques. However, it should be emphasised that GPS is not simply an alternative to existing techniques but has advantages and disadvantages which need to be evaluated. Three case studies in the uplands of Northern England demonstrate the trade-off between the advantage of speed and disadvantage of reduced accuracy afforded by GPS. The studies are concerned with the rapid mapping of flood extent based on ephemeral flow limit indicators; detailed mapping of alluvial fan surfaces and associated sediment sources; and the spatial distribution of colluvial sediment supply and downstream movement of bedload slugs. The extent to which approaches based on differential GPS, in combination with more traditional survey techniques, can provide information on sediment dynamics or validation of distributed models is evaluated.
Page 243. FLUVIAL HAZARDS IN A STEEPLAND MOUNTAIN ENVIRONMENT, SOUTHERN BOLIVIA JEFF WARBURTON. M... more Page 243. FLUVIAL HAZARDS IN A STEEPLAND MOUNTAIN ENVIRONMENT, SOUTHERN BOLIVIA JEFF WARBURTON. MARK MACKLIN. DAVID PRESTON 1. Introduction Mountainous environments are highly active geomorphologically ...
Globally, peatlands account for circa 50% of terrestrial carbon storage containing as much carbon... more Globally, peatlands account for circa 50% of terrestrial carbon storage containing as much carbon as is present in the atmosphere. The uplands of the UK have an extensive cover of blanket peat but much of it is actively eroding. This paper presents a detailed organic sediment budget for a blanket peat catchment in the north Pennines and comparative data from a catchment in the southern Pennines. The catchments have total sediment yields (organic and mineral) of 44 and 267 t km− 2 a− 1 and organic sediment yields 31 and 195 t km− 2 a− 1, respectively. They represent two extremes of a spectrum of eroded peat catchments. It is demonstrated that the lower sediment yields in the north Pennines are associated with extensive natural revegetation of the catchment and consequent reductions in slope-channel linkage. Construction of a carbon budget for the north Pennine catchment demonstrates that particulate carbon losses associated with the fluvial suspended sediment load are the largest single carbon loss from the system. The system is currently close to carbon neutral but much higher carbon losses associated with actively eroding systems such as the south Pennine site would make these systems a major carbon source. The possibility that enhanced summer temperatures and winter storminess will accelerate erosion of upland mires means there is a risk that physical degradation of peatlands could become a significant positive feedback on global warming. Mitigation of these potential global effects will depend on local management informed by a clear understanding of peatland sediment dynamics. The sediment budget data here suggest that in gullied peatlands revegetation of gully floors is an effective control on sediment flux so that techniques such as gully blocking are likely to be effective approaches to erosion control.
AbstractA linear stability analysis using a flow model appropriate for steep, rough channels sugg... more AbstractA linear stability analysis using a flow model appropriate for steep, rough channels suggests that initial wavelength selection of alternate bars is strong for extant flow conditions in North Boulder Creek, Colorado. This is due in part to effects of velocity correlation terms in the streamwise momentum balance that involve deviations in velocity components about depth-averaged values. The analysis also suggests that alternate bars and midchannel bars can “compete” during initial bed form growth at low sediment transport rates. These points are consistent with the observation that alternate and midchannel bar forms in North Boulder Creek have comparable topographic relief, as revealed by spectral analysis of the bed topography. Moreover, the dominant wavelengths of these bar forms match the fastest growing wavelengths predicted by the stability analysis. However, whereas the alternate bar topography can be attributed to free-bar growth, much of the midchannel bar topography probably is a forced-bar topography that is related to flow accelerations associated with variations in channel width. The complex bed topography of North Boulder Creek thus consists of a decipherable mixture of bed forms that have evolved as free alternate bars together with forced bars whose positions and geometries are fixed in relation to variations in channel width or to large immobile boulders.
Zeitschrift für Geomorphologie, Supplementary Issues, 2012
ABSTRACT Projected climate change in cold environments is expected to alter melt-season duration ... more ABSTRACT Projected climate change in cold environments is expected to alter melt-season duration and intensity, along with the number of extreme rainfall events, total annual precipitation and the balance between snowfall and rainfall. In addition, changes to the thermal balance are expected to reduce the extent of permafrost and seasonal ground frost and increase active layer depth. These effects will change surface environments in cold climate environments and alter the flfl uxes of sediments, nutrients and solutes, but the absence of data and coordinated quantitative analysis to understand the sensitivity of the surface environment are acute in cold environments. The I.A.G/A.I.G. SEDIBUD (Sediment Budgets in Cold Environments) Programme, building on the ESF SEDIFLUX (Sedimentary Source-to-Sink-Fluxes in Cold Environments) Network, has been formed to address this key knowledge gap. Coordinated efforts are carried out to quantify, compare and model sedimentary flfl uxes and budgets in 38 selected SEDIBUD Key Test Sites (cold environment catchments) worldwide.
Geomorphological Processes and Landscape Change, 2001
While the outlines of the lowlands are touched with the instability that marks everything human, ... more While the outlines of the lowlands are touched with the instability that marks everything human, these far heights seem to remain impassive and unaffected, as if the hand of time had passed them by. Hence the everlasting hills have ever been favourite emblems, not only ...
This study estimates the complete carbon budget of an 11.4 km2 peat-covered catchment in Northern... more This study estimates the complete carbon budget of an 11.4 km2 peat-covered catchment in Northern England. The budget considers both fluvial and gaseous carbon fluxes and includes estimates of particulate organic carbon (POC); dissolved organic carbon (DOC); excess dissolved CO2; release of methane (CH4); net ecosystem respiration of CO2; and uptake of CO2 by primary productivity. All components except CH4 were measured directly in the catchment and annual carbon budgets were calculated for the catchment between 1993 and 2005 using both extrapolation and interpolation methods. The study shows that: Over the 13 year study period the total carbon balance varied between a net sink of − 20 to − 91 Mg C/km2/yr. The biggest component of this budget is the uptake of carbon by primary productivity (− 178 Mg C/km2/yr) and in most years the second largest component is the loss of DOC from the peat profile (+ 39 Mg C/km2/yr). Direct exchanges of C with the atmosphere average − 89 Mg C/km2/yr in the catchment. Extrapolating the general findings of the carbon budget across all UK peatlands results in an approximate carbon balance of − 1.2 Tg C/yr (± 0.4 Pg C/yr) which is larger than previously reported values. Carbon budgets should always be reported with a clear statement of the techniques used and errors involved as this is significant when comparing results across studies.
Abstract This paper describes and analyses the structure and deposits of a large UK peat slide, l... more Abstract This paper describes and analyses the structure and deposits of a large UK peat slide, located at Hart Hope in the North Pennines, northern England. This particular failure is unusual in that it occurred in the winter (February, 1995) and shows excellent preservation ...
... uncommon (Dykes and Kirk, 2006), but they have been reported at upland locations from Dartmoo... more ... uncommon (Dykes and Kirk, 2006), but they have been reported at upland locations from Dartmoor, SW England (Vancouver, 1808), to Shetland, N Scotland (Veyret and ... On other parts of the summit ridge and adjacent slopes peat extraction by tine-cutting was attempted ...
Published accounts of peat mass movements throughout the last 500 years reveal common characteris... more Published accounts of peat mass movements throughout the last 500 years reveal common characteristics among the failures; however, there has been no consistency in the terminology used to describe them. Given the apparently increasing frequency of peat failures in the British Isles and the possibility of more peat failures elsewhere in the world as a consequence of climate change, there is a need for a specific classification scheme. This paper proposes a scheme that uses clearly defined terms that can be readily applied and reliably used to understand and assess future hazards from peat mass movements. The paper begins with a general definition of what should constitute a ‘peat failure’, then presents a precisely defined classification scheme for peat landslides (i.e. excluding creep), using type of peat deposit and failure morphology as the key criteria. The new scheme for peat failures is discussed in the context of existing landslide classification systems. Definitions are provided for bog bursts (flow failure of raised bogs), bogflows (flow failure of blanket bogs), bog slides (shear failure and sliding of blanket bogs), peat slides (shear failure at peat–mineral interface in blanket bogs), peaty-debris slides (shear failure within mineral substrate beneath blanket bogs) and peat flows (natural failures of other types of peat deposits including flow failure caused by head-loading). Some practical problems of classifying peat failures are discussed.
Recent technological developments in the application of the Global Positioning System (GPS) offer... more Recent technological developments in the application of the Global Positioning System (GPS) offer the prospect of rapidly mapping difficult terrain and quantifying temporal and spatial dynamics of erosion and sedimentation. While many developments in GPS have been considered from the viewpoint of geodesy, their versatility in geomorphological situations has had limited attention. In particular, the improved accuracy and reduced costs of some GPS systems makes them attractive for many mapping applications. Differential GPS allows the logging of position of a mobile receiver relative to a control station. In difficult terrain, such as uplands, the location and distribution of survey points by GPS is much more efficient than conventional survey techniques. However, it should be emphasised that GPS is not simply an alternative to existing techniques but has advantages and disadvantages which need to be evaluated. Three case studies in the uplands of Northern England demonstrate the trade-off between the advantage of speed and disadvantage of reduced accuracy afforded by GPS. The studies are concerned with the rapid mapping of flood extent based on ephemeral flow limit indicators; detailed mapping of alluvial fan surfaces and associated sediment sources; and the spatial distribution of colluvial sediment supply and downstream movement of bedload slugs. The extent to which approaches based on differential GPS, in combination with more traditional survey techniques, can provide information on sediment dynamics or validation of distributed models is evaluated.
Page 243. FLUVIAL HAZARDS IN A STEEPLAND MOUNTAIN ENVIRONMENT, SOUTHERN BOLIVIA JEFF WARBURTON. M... more Page 243. FLUVIAL HAZARDS IN A STEEPLAND MOUNTAIN ENVIRONMENT, SOUTHERN BOLIVIA JEFF WARBURTON. MARK MACKLIN. DAVID PRESTON 1. Introduction Mountainous environments are highly active geomorphologically ...
Globally, peatlands account for circa 50% of terrestrial carbon storage containing as much carbon... more Globally, peatlands account for circa 50% of terrestrial carbon storage containing as much carbon as is present in the atmosphere. The uplands of the UK have an extensive cover of blanket peat but much of it is actively eroding. This paper presents a detailed organic sediment budget for a blanket peat catchment in the north Pennines and comparative data from a catchment in the southern Pennines. The catchments have total sediment yields (organic and mineral) of 44 and 267 t km− 2 a− 1 and organic sediment yields 31 and 195 t km− 2 a− 1, respectively. They represent two extremes of a spectrum of eroded peat catchments. It is demonstrated that the lower sediment yields in the north Pennines are associated with extensive natural revegetation of the catchment and consequent reductions in slope-channel linkage. Construction of a carbon budget for the north Pennine catchment demonstrates that particulate carbon losses associated with the fluvial suspended sediment load are the largest single carbon loss from the system. The system is currently close to carbon neutral but much higher carbon losses associated with actively eroding systems such as the south Pennine site would make these systems a major carbon source. The possibility that enhanced summer temperatures and winter storminess will accelerate erosion of upland mires means there is a risk that physical degradation of peatlands could become a significant positive feedback on global warming. Mitigation of these potential global effects will depend on local management informed by a clear understanding of peatland sediment dynamics. The sediment budget data here suggest that in gullied peatlands revegetation of gully floors is an effective control on sediment flux so that techniques such as gully blocking are likely to be effective approaches to erosion control.
AbstractA linear stability analysis using a flow model appropriate for steep, rough channels sugg... more AbstractA linear stability analysis using a flow model appropriate for steep, rough channels suggests that initial wavelength selection of alternate bars is strong for extant flow conditions in North Boulder Creek, Colorado. This is due in part to effects of velocity correlation terms in the streamwise momentum balance that involve deviations in velocity components about depth-averaged values. The analysis also suggests that alternate bars and midchannel bars can “compete” during initial bed form growth at low sediment transport rates. These points are consistent with the observation that alternate and midchannel bar forms in North Boulder Creek have comparable topographic relief, as revealed by spectral analysis of the bed topography. Moreover, the dominant wavelengths of these bar forms match the fastest growing wavelengths predicted by the stability analysis. However, whereas the alternate bar topography can be attributed to free-bar growth, much of the midchannel bar topography probably is a forced-bar topography that is related to flow accelerations associated with variations in channel width. The complex bed topography of North Boulder Creek thus consists of a decipherable mixture of bed forms that have evolved as free alternate bars together with forced bars whose positions and geometries are fixed in relation to variations in channel width or to large immobile boulders.
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