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    ABSTRACT: Glacial geomorphological mapping of southern Alberta, Canada, reveals landform assemblages that are diagnostic of terrestrial-terminating ice streams/fast flowing outlet glaciers with lobate snouts. Spatial variability in features that comprise the landform assemblages reflects changes in (a) palaeo-ice stream activity (switch on/off); and (b) snout basal thermal regimes associated with climate sensitive, steady state flow. Palaeo-ice stream tracks reveal distinct inset sequences of fan-shaped flowsets indicative of receding lobate ice stream margins. Former ice lobe margins are demarcated by (a) major, often glacially overridden transverse moraine ridges, commonly comprising glacitectonically thrust bedrock; and (b) minor, closely spaced recessional push moraines and hummocky moraine arcs. Details of these landform types are well exhibited around the former southern margins of the Central Alberta Ice Stream, where larger scale, more intensive mapping identifies a complex glacial geomorphology comprising minor transverse ridges (MTR types 1–3), hummocky terrain (HT types 1–3), flutings, and meltwater channels/spillways. The MTR type 1 constitute the summit corrugation patterns of glacitectonic thrust moraines or major transverse ridges and have been glacially overrun and moderately streamlined. The MTR type 2 sequences are recessional push moraines similar to those developing at modern active temperate glacier snouts. The MTR type 3 document moraine construction by incremental stagnation because they occur in association with hummocky terrain. The close association of hummocky terrain with push moraine assemblages indicates that they are the products of supraglacial controlled deposition on a polythermal ice sheet margin, where the HT type 3 hummocks represent former ice-walled lake plains. The ice sheet marginal thermal regime switches indicated by the spatially variable landform assemblages in southern Alberta are consistent with palaeoglaciological reconstructions proposed for other ice stream/fast flow lobes of the southern Laurentide Ice Sheet, where alternate cold, polythermal, and temperate marginal conditions associated with climate sensitive, steady state flow sequentially gave way to more dynamic streaming and surging activity.
    Geomorphology 01/2014; 204:86–113.
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    ABSTRACT: This paper considers the role that microseismic ground displacements may play in fracturing rock via cyclic loading and subcritical crack growth. Using a coastal rock cliff as a case study, we firstly undertake a literature review to define the spatial locations that may be prone to microseismic damage. It is suggested that microseismic weakening of rock can only occur in ‘damage accumulation zones’ of limited spatial extent. Stress concentrations resulting from cliff height, slope angle and surface morphology may nucleate and propagate a sufficiently dense population of microcracks that can then be exploited by microseismic cyclic loading. We subsequently examine a 32-day microseismic dataset obtained from a coastal cliff-top location at Staithes, UK. The dataset demonstrates that microseismic ground displacements display low peak amplitudes that are punctuated by periods of greater displacement during storm conditions. Microseismic displacements generally display limited preferential directivity, though we observe rarely occurring sustained ground motions with a cliff-normal component during storm events. High magnitude displacements and infrequently experienced ground motion directions may be more damaging than the more frequently occurring, reduced magnitude displacements characteristic of periods of relative quiescence. As high magnitude, low frequency events exceed and then increase the damage threshold, these extremes may also render intervening, reduced magnitude microseismic displacements ineffective in terms of damage accumulation as a result of crack tip blunting and the generation of residual compressive stresses that close microcracks. We contend that damage resulting from microseismic ground motion may be episodic, rather than being continuous and in (quasi-)proportional and cumulative response to environmental forcing. A conceptual model is proposed that describes when and where microseismic ground motions can operate effectively. We hypothesise that there are significant spatial and temporal limitations on effective microseismic damage accumulation, such that the net efficacy of microseismic ground motions in preparing rock for fracture, and hence in enhancing erosion, may be considerably lower than previously suggested in locations where high magnitude displacements punctuate ‘standard’ displacement conditions. Determining and measuring the exact effects of microseismic ground displacement on damage accumulation and as a trigger to macro-scale fracture in the field is not currently possible, though our model remains consistent with field observations and conceptual models of controls on rockfall activity.
    Geomorphology 01/2014; 207:161–173.
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    ABSTRACT: This paper aims to evaluate how varying degrees of land-use/cover (LULC) changes across sub-catchments affect a flood peak at the catchment outlet. The study site was the Konar catchment, a part of the upper Damodar Basin in eastern India. A HEC-HMS model was set up to simulate rainfall–runoff processes for two LULC scenarios three decades apart. Because of sparse data availability at the study site, we used the Natural Resource Conservation Service (NRCS) curve number (CN) approach to account for the effect of LULC and soil on the hydrologic response of the catchment. Although a weak (r = 0.53) but statistically significant positive linear correlation was found between sub-catchment wise LULC changes and the magnitude of the flood peak at the catchment outlet, a number of sub-catchments showed marked deviations from this relationship. The varying timing of flow convergence at different stream orders due to localised LULC changes makes it difficult to upscale the conventional land-use and runoff relationship, evident at the plot scale, to a large basin. However, a simple modelling framework is provided based on easily accessible input data and a freely available and widely used hydrological model (HEC-HMS) to check the possible effect of LULC changes at a particular sub-catchment on the hydrograph at the basin outlet.
    CATENA. 01/2014; 118:28–40.
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    ABSTRACT: Research around micro-hydro power is focused on technical aspects with limited understanding of the social organisation and environmental implications. We examine the ways in which micro-hydro is engaged by people and organisations as a means of contributing to the UK's policy ambition for renewable energy. We bring to the fore the way in which expertise is used and contested. A web based review of micro-hydro schemes in the UK was undertaken and a detailed evaluation of two schemes in the North of England was conducted to determine how expertise and contestation figures in community schemes. Results demonstrate a rapid expansion of micro-hydro in the UK. Ownership/control is highly ‘community based’. Until now research around micro-hydro has been dominated by technical approaches with schemes defined in terms of hardware. We propose a third dimension to Walker and Cass's (2007) classification of renewable energy developments: the environmental dimension. We suggest this dimension of micro-hydro is critical, both in terms of the extent to which resources can be realised but also the ways in which it might attract controversy, in particular around how expertise is used and valued.
    Energy Policy. 01/2014; 68:92–101.
  • Journal of Public Health 11/2013;
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    ABSTRACT: The aim is to investigate the evolution of the subglacial landscape of Antarctica using an ice sheet and erosion model. We identify different stages of continental glaciation and model the erosion processes associated with each stage. The model links erosion to the basal thermal regime and indicates that much of the Antarctic interior may have been subject to less than 200 m of erosion. The depth of erosion reflects the presence or absence of warm-based ice and the consistency of ice flow direction. This information, linked with knowledge about landscapes of glaciation in the northern hemisphere and some simple but robust assumptions about initial topography, is used to generate a map of the subglacial Antarctic landscape in which much of the lowland interior resembles the landscapes of areal scouring typical of the Laurentian and Scandinavian shields. Near the continental margins selective linear erosion has overdeepened pre-existing river valleys by as much as 2.8 km. High elevation plateaus adjacent to such drainage systems have survived largely unmodified under cold-based ice. High erosion rates result from steep thermal gradients in basal ice. Mountain regions such as the Gamburtsev Mountains, uplands in Dronning Maud Land and massifs in West Antarctica are likely to bear features of local alpine glaciation. Such landscapes may have been protected under cold-based ice for the last 34 Myrs or possibly longer.
    Earth and Planetary Science Letters 09/2013;
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    ABSTRACT: The 1960, and 2010 Chilean great earthquakes provide modern analogues for the sedimentary signatures of the largest megathrust events and their accompanying tsunamis. This paper presents lithological and diatom assemblage data from five sites and provides key insights for the development of longer earthquake chronologies, essential for assessing the seismic hazards associated with a subduction zone. We find that the 1960 and 2010 tsunami deposits are fragmentary, variable and have no unique, diagnostic diatom assemblage. Where rapid postseismic sedimentation occurs, our diatom-based transfer function model gives estimates of coseismic deformation that agree with independent estimates of land-level change. Sedimentary hiatuses at two sites following the 2010 earthquake suggest that the magnitude of coseismic deformation may be underestimated in fossil records. Where sediment accumulation allows, criteria for distinguishing between seismic and non-seismic stratigraphies based on evidence for the largest plate boundary earthquakes are corroborated by the lesser magnitude earthquake of 2010. The key to reconstructing earthquake characteristics, such as rupture magnitude and differences between plate-boundary and upper plate sources, depends on applying explicit stratigraphic assessment criteria at multiple sites in order to identify the spatial pattern of deformation associated with each earthquake.
    Quaternary Science Reviews 09/2013; 75:11–21.
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    ABSTRACT: Observations of ocean-terminating outlet glaciers in Greenland and West Antarctica indicate that their contribution to sea level is accelerating as a result of increased velocity, thinning and retreat. Thinning has also been reported along the margin of the much larger East Antarctic ice sheet, but whether glaciers are advancing or retreating there is largely unknown, and there has been no attempt to place such changes in the context of localized mass loss or climatic or oceanic forcing. Here we present multidecadal trends in the terminus position of 175 ocean-terminating outlet glaciers along 5,400 kilometres of the margin of the East Antarctic ice sheet, and reveal widespread and synchronous changes. Despite large fluctuations between glaciers--linked to their size--three epochal patterns emerged: 63 per cent of glaciers retreated from 1974 to 1990, 72 per cent advanced from 1990 to 2000, and 58 per cent advanced from 2000 to 2010. These trends were most pronounced along the warmer western South Pacific coast, whereas glaciers along the cooler Ross Sea coast experienced no significant changes. We find that glacier change along the Pacific coast is consistent with a rapid and coherent response to air temperature and sea-ice trends, linked through the dominant mode of atmospheric variability (the Southern Annular Mode). We conclude that parts of the world's largest ice sheet may be more vulnerable to external forcing than recognized previously.
    Nature 08/2013; 500(7464):563-6.
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    ABSTRACT: This paper provides important contextual and service implementation data by exploring participant experiences of a pilot case management intervention for long-term incapacity benefit (IB) recipients. Service experiences were assessed via a postal questionnaire and semi-structured qualitative telephone interviews. Data from 77 service user questionnaires and 20 semi-structured qualitative interviews were obtained. Questionnaire data were analysed using SPSS and telephone interviews were transcribed, thematically coded and analysed using NVivo. Respondents were generally positive about their experience of the intervention and particularly the benefit gained from the personal support that case managers provided. However, they also made suggestions about how the service could be delivered more effectively particularly in terms of the duration of the treatments and increasing the level of face-to-face support. Case management approaches may offer a supportive environment in which the health needs of those in the long-term receipt of IB can be addressed.
    Journal of Public Health 06/2013;
  • Social Science [?] Medicine 04/2013;
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