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Blyth, United Kingdom

Robins N.S.,British Geological Survey | Pye K.,Kenneth Pye Associates Ltd | Wallace H.,Ecological Surveys Bangor
Journal of Coastal Conservation | Year: 2013

Whiteford Burrows is a coastal dune spit wetland in South Wales that is susceptible to morphological change. The height of the ridge of groundwater within the sand aquifer is essentially proportional to the width of the spit. The water table elevation impacts both the frequency and duration of slack flooding events and, therefore, slack ecology. A severe late winter storm event on 17 March 1995 caused extensive erosion of the foreshore, reducing the effective width of the dune system by 4 % and the water table elevation by up to 1 m. This observed relationship allows water level elevations in the dune system to be hindcast using historical maps and air photos which record past change in dune morphology. These historical data indicate that the dunes were relatively broad in the nineteenth century and the slacks were humid and liable to regular winter flooding. The system slowly dried out towards the 1940s as the spit thinned, when subsequent widening allowed the water table to rise and once again flood slack floors in winter. Despite these changes, the alkalinity of the Whiteford Burrows dune system has inhibited organic matter accumulation and maintained conditions needed for the persistence of a diverse basiphilous vegetation assemblage in many of the slacks. © 2013 Springer Science+Business Media Dordrecht. Source


Pye K.,Kenneth Pye Associates Ltd | Pye K.,University of Southampton | Blott S.J.,Kenneth Pye Associates Ltd
Journal of Coastal Conservation | Year: 2015

The Holderness coast is composed largely of ‘soft’ Quaternary sediments, mainly glacial till, which form cliffs up to 38 m high. Cliff erosion rates have shown a complex pattern of spatial and temporal variation over the past 160 years which reflects interaction of natural processes and human interventions, notably building of coastal defences at Bridlington, Hornsea, Withernsea, Mappleton, and Easington. A former single coastal cell, extending between Flamborough Head and the Spurn Peninsula, is breaking down into a series of separate sub-cells defined by sections of defended coast. Between these ‘hard points’ the shoreline is developing as a series of shallow bays which are deepest immediately to the south (downdrift) of the defences. Superimposed on this pattern are smaller-scale variations which reflect the effects of dynamic beach features on wave energy exposure at the cliff toe. Cliff recession rates can exceed 4 m a−1 when beach troughs lie in front of the cliff toe but may fall close to zero as a sand wave passes. Erosion rates on the undefended coast showed an increase in the period 1989–2013 compared with earlier epochs and further increases can be anticipated due to sea level rise over the course of the next century. The effects of climate change on storminess remain uncertain but any increase would further enhance the erosional trend. The implications are future increased rates of cliff top recession and increased risk to infrastructure close to the coast in the medium to longer term. Increased erosion rates will increase the rate of sediment supply to the nearshore system, but it is unclear how much of the fine sediment released will be transported into the Humber estuary to maintain tidal flats and saltmarshes, and how much of the sand and gravel will travel along the beach system to sustain the Spurn Peninsula. © 2015, Springer Science+Business Media Dordrecht. Source


Pye K.,Kenneth Pye Associates Ltd | Pye K.,University of Southampton | Blott S.J.,Kenneth Pye Associates Ltd
Estuarine, Coastal and Shelf Science | Year: 2014

This paper provides an overview of the geomorphological characteristics of UK estuaries and the factors which control them. Many of the features included in previous classifications of UK estuaries are not true estuaries since they do not possess significant river influence. The features considered in this paper to be 'true' estuaries are divided into 'restricted entrance' and 'unrestricted entrance' types on the grounds that the size and geometry of the estuary mouth exerts a critical influence on water levels, tidal currents, wave action, sediment transport and morphological evolution. An estuary which has a wide mouth, narrows and becomes shallower towards the head is likely to be flood dominated, especially if it has a large tidal range, whereas an estuary which has a narrow mouth and widens and/or becomes deeper towards the head is more likely to display ebb dominance, especially if it has a relatively small tidal range. Wide-mouthed estuaries are influenced to a greater degree by wave processes than estuaries with a narrow mouth. Previous authors have hypothesised that estuaries may maintain a state of dynamic equilibrium through alternating periods of flood and ebb dominance, but it is concluded that there is presently no substantive evidence to support this hypothesis. UK estuaries have been affected to varying degrees by embanking, land claim, dredging, sea wall breaching and managed realignment. Some estuaries have adjusted quickly to such perturbations, but others continue to show progressive change, either sedimentary infilling or erosion and sediment loss. The quantification of estuary morphometry, identification of change over time, and testing of hypotheses regarding the morphodynamics and stability of estuaries requires adequate bathymetric/topographic, hydrodynamic and sediment data. At present, such data are available for relatively few UK estuaries. © 2014 Elsevier Ltd. Source


Pye K.,Kenneth Pye Associates Ltd | Blott S.J.,Kenneth Pye Associates Ltd | Howe M.A.,Natural Resources Wales
Journal of Coastal Conservation | Year: 2014

Welsh coastal dune systems have become increasingly vegetated in recent decades. Several rare species of plants and invertebrates have declined dramatically in abundance, and in some areas lost entirely. Of the ten dune habitats and species recognized as being features of European importance within the Welsh Natura 2000 sites, nine are currently in Unfavourable condition on at least one site. The decline in active aeolian processes has also reduced the geomorphological interest of the sites, several of which were designated as Geological Conservation Review sites principally on the basis of their physical processes and landforms. The decline in bare sand area between the 1940-50s and 2009 has been quantified at twelve Welsh dune sites using aerial photography and GIS. The decline ranged from 41 % at Gronant Dunes and Talacre Warren to 97 % at Kenfig Burrows, with an average of 81 %. Morfa Dyffryn had the highest remaining percentage of bare sand in 2009 (20 %), with 30-40 % coverage of mobile dune and pioneer communities, while seven sites had < 5 % bare sand. Dune stabilization over the past 60 years has been favoured by a number of factors, including less windy conditions, higher temperatures and longer growing season, increased atmospheric nitrogen deposition, a reduction in grazing intensity, and dune management policies aimed at controlling mobile sand. Climate change projections suggest that, in the next 50 to 100 years, Wales and adjoining areas are likely to experience higher temperatures and higher rainfall, especially in winter, and a further slight reduction in wind speeds. Without intervention, dune and dune slack habitats are likely to be increasingly replaced by fixed dune grassland and scrub, resulting in the extinction of rare plants, invertebrates and other species which require open, mobile conditions. Several intervention options exist, ranging in scale and potential impact. Increased livestock grazing, re-introduction of rabbits, scrub clearance, turf stripping and the creation of shallow 'scrapes' can be beneficial but will not by themselves create self-sustaining mobile dunes. In order to have any chance of achieving any significant impact, larger-scale intervention measures, involving large-scale vegetation removal and sand-re-profiling, will be required. At least in the short-term, maintenance measures will be required to prevent vegetation re-growth, and the challenge will be to encourage the development of mobile dune features which will be naturally mobile in the medium to longer term. © 2013 Springer Science+Business Media Dordrecht. Source


Blott S.J.,Kenneth Pye Associates Ltd | Pye K.,Kenneth Pye Associates Ltd
Sedimentology | Year: 2012

This paper provides a review of different particle size scales, size class terminology and particle size distribution ('textural') classification schemes which are widely used in sedimentology, geomorphology, soil science, aquatic ecology and civil engineering. It is concluded that a revised system of size class nomenclature, based on the Udden (1898) and Wentworth (1922) schemes, provides the most logical and consistent framework for use with sediments and a wide range of other particulate materials. A refined scheme is proposed which has five first-order size classes (boulder, gravel, sand, silt and clay), each of which has five second-order subdivisions with limits defined at one phi intervals. The scheme is simple and intuitively easy to understand. The paper also provides a review of previous schemes that have been proposed to describe and classify sediments on the basis of the proportions of gravel, sand and mud, or sand, silt and clay using trigons (also termed ternary diagrams). Many of these schemes do not have a logical basis and provide limited or uneven resolution. New gravel, sand and mud and sand, silt and clay classification systems are proposed that are both more logical and provide greater discriminatory power than previous schemes; they are therefore more suitable for use in environmental and forensic investigations. A new Microsoft Excel® program, freely available to download from http://www.kpal.co.uk, allows rapid classification of sediments based on the proportions of gravel, sand and mud and sand, silt and clay proportions and graphical comparison of the data for different sample groups. © 2012 The Authors. Journal compilation © 2012 International Association of Sedimentologists. Source

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