Geomorphology of Upland Peat Erosion, Form and Landscape Change

About this book

Erosion of upland blanket peat is recognized as a major environmental problem, degrading habitats, leading to loss of amenity, and water-colouration problems and increased sedimentation in reservoirs. Despite the scale of the problem relatively little process based work has been done on the geomorphology of eroding blanket peat. This new study will present the most detailed work to date on the nature of the processes controlling peat erosion and on the nature of the sediment budget of eroding peatlands. Although the focus in the book falls on upland Britain (which has 8 per cent of the world's total resource of blanket peat), the authors fully recognize the international dimension of the problem and make wide-ranging comparisons.

Contents

Series Editors' PrefaceAcknowledgements1. Introduction1.1 The aims of this volume1.1.1 Thematic coverage1.1.2 Geographical context1.2 Terminology, definitions and peatland geomorphology1.2.1 Definitions of Peat1.2.2 The Physical and geotechnical properties of peat1.2.3 Peatland classification1.3 The geography of blanket mire complexes1.4 Patterns of peat erosion in space and time1.4.1 The onset of peat erosion1.4.2 Direct observation of the onset of erosion1.5 Causes of peat erosion1.6 A brief history of the evolution of peatland geomorphology1.6.1 Accounts of erosion in the natural science tradition1.6.2 Descriptive accounts of widespread peat erosion1.6.3 Quantitative observations of blanket peatlands1.7 Structure of this volume and the peat land system model 2. The Hydrology of Upland Peatlands2.1 Introduction2.2. Controls on water movement in peatland systems2.2.1 Hydraulic conductivity of upland peat soils2.2.2 The diplotelmic mire hypothesis2.2.3 Groundwater flow in upland peatlands2.2.4 Evaporation2.2.5 Runoff generation2.2.6 The Water balance of ombrotrophic mires2.3 Geomorphology and the hydrology of upland peatlands3. Sediment Production3.1 Introduction3.1.1 Monitoring sediment production using erosion pins3.1.2 Sediment trap data3.2 Sediment production as a control on catchment sediment flux3.3 Evidence from field observation3.3.1 Climate correlations with trap data3.3.2 Direct observations of surface change3.4 Evidence from controlled experiments3.5 Timescales of sediment supply3.6 Conclusion4. Fluvial Processes and Peat Erosion4.1 Introduction4.2 Gully erosion of blanket peat4.2.1 Gully morphology and topology4.2.2 Processes of Gully erosion 4.3 Erosion and transport of peat in perennial stream channels4.3.1 Production of peat blocks by fluvial erosion4.3.2 Transport of peat blocks in stream channels4.3.3 The fate of fine peat sediment in channel4.4 Sediment yield4.4.1 A conceptual model of sediment dynamics in eroding blanket peatlands4.4.2 Sediment yield, sediment supply and assessing catchment erosion status4.5 Conclusions5. Slope Processes and Mass Movements5.1 Introduction5.2 Peat covered hillslopes5.2.1 Limits to the stability of peat on slopes5.2.2 Creep on peat hillslopes5.3 Morphology of rapid peat mass movements5.3.1 Source zone5.3.2 Rafted peat debris 5.3.3 Runout track 5.3.4 Secondary tension and compression features5.3.5 Bog burst and peat slides - are they different?5.4 Mechanism of peat failure5.4.1 Speed of failure and movement5.5 Significance of surface hydrology in peat failures5.5.1 Water content and pore pressures5.5.2 Rainfall5.5.3 Slope drainage5.6 Stability analysis and modelling of peat mass movements5.7 The changing frequency of peat mass movements over time5.8 Summary and overall framework6. Wind Erosion Processes6.1 Introduction6.2 Wind erosion in the uplands and the significance in peatland environments6.3 Mechanisms of wind erosion6.4 The significance of wet or dry wind erosion processes6.5 Direct measurements of wind erosion of peat6.6 Aeolian landforms6.7 The significance of wind erosion for landscape development in upland peatlands6.8 Conclusions6.8.1 Further research - an agenda for pluvio-aeolian studies of upland peat7. Peat Erosion Forms - from Landscape to Micro-relief7.1 Rationale and introduction7.2 Macroscale - Region / Catchment Scale 7.3 Mesoscale - Slope-Catena Scale7.4 Microscale - material structure scale 7.5 Linking the geomorphological and the ecohydrological7.6 Conclusions8. Sediment Dynamics, Vegetation, and Landscape Change8.1 Introduction8.2 The effect of peatland dynamics on long term sediment budgets8.3 Mass balance evidence of patterns of long term erosion8.4 Re-vegetation of eroding peatlands8.4.1 Artificial re-vegetation of bare peat surfaces8.4.2 Natural revegetation of eroded landscapes8.5 Controls and mechanisms of natural re-vegetation8.5.1 Extrinsic controls on re-vegetation8.5.2 Intrinsic controls on re-vegetation8.5.3 Eriophorum spp. as Keystone Species for Re-vegetation of Eroded Peatlands8.5.4 Geomorphology, ecology, and 'erosion-regeneration complexes'8.5.5 Re-vegetation dynamics and long term patterns of erosion8.6 Stratigraphic evidence of erosion and re-vegetation 8.7 The future of blanket peat sediment systems8.8 Changes in pollution climate8.9 Climate change impacts8.9.1 Increased summer drought 8.9.2 Increased summer and winter storminess8.9.3 Changes in the growing season and vegetation 8.9.4 Overall response of the peat land system8.10 Relative importance of peat erosion in wider upland sediment budgets8.11 Conclusions9. Implications and Conclusions9.1 Implications of widespread peat erosion9.2 Upland peatland erosion and carbon budgets9.2.1 Case Study Example: the Rough Sike sediment-carbon budget9.3 Release of stored contaminants from eroding peatlands9.4 Restoration of eroded upland peatlands9.4.1 Frameworks for restoration9.4.2 Approaches to restoration9.4.3 Implications of the landsystems model and sediment budget work for restoration9.5 Conclusions 9.5.1 The nature of upland peatlands9.5.2 Geomorphological processes in upland peatlands9.5.3 The future of upland peatlands9.5.4 Representativeness of the peat land system modelIndex

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Biography

Martin Evans is a reader in geomorphology at the University of Manchester. Jeff Warburton is currently a reader in geomorphology in the Department of Geography at Durham University.