Geomorphology of upland peat: erosion, form, and landscape change

Contents......Page 8
Series Editors’ Preface......Page 12
Acknowledgements......Page 13
Figure and Table Acknowledgements......Page 15
1.1.1 Thematic coverage......Page 20
1.1.2 Geographical context......Page 21
1.2.1 Definitions of peat......Page 22
1.2.3 Peatland classification......Page 25
1.3 The Geography of Blanket Mire Complexes......Page 30
1.4 Patterns of Peat Erosion in Space and Time......Page 34
1.4.1 The onset of peat erosion......Page 37
1.4.2 Direct observation of the onset of erosion......Page 39
1.5 Causes of Peat Erosion......Page 40
1.6 A Brief History of the Evolution of Peatland Geomorphology......Page 41
1.6.2 Descriptive accounts of widespread peat erosion......Page 42
1.6.3 Quantitative observations of blanket peatlands......Page 43
1.7 Structure of this Volume and the Peat Landsystem Model......Page 45
2.2.1 Hydraulic conductivity of upland peat soils......Page 47
2.2.2 The diplotelmic mire hypothesis......Page 49
2.2.3 Groundwater flow in upland peatlands......Page 53
2.2.4 Evaporation......Page 56
2.2.5 Runoff generation......Page 57
2.2.6 The water balance of ombrotrophic mires......Page 66
2.3 Geomorphology and the Hydrology of Upland Peatlands......Page 68
3.1.1 Monitoring sediment production using erosion pins......Page 73
3.1.2 Sediment trap data......Page 75
3.2 Sediment Production as a Control on Catchment Sediment Flux......Page 80
3.3.1 Climate correlations with trap data......Page 84
3.3.2 Direct observations of surface change......Page 86
3.4 Evidence from Controlled Experiments......Page 88
3.5 Timescales of Sediment Supply......Page 92
3.6 Conclusion......Page 93
4.2 Gully Erosion of Blanket Peat......Page 95
4.2.1 Gully morphology and topology......Page 96
4.2.2 Fluvial erosion in ephemeral hillslope gullies......Page 100
4.2.3 Sediment delivery from hillslope gullies......Page 104
4.3.1 Production of peat blocks by fluvial erosion......Page 106
4.3.2 Transport of peat blocks in stream channels......Page 110
4.3.3 The fate of fine peat sediment in channels......Page 112
4.4.2 Suspended sediment yields......Page 114
4.4.3 Dissolved load......Page 116
4.4.4 A conceptual model of sediment dynamics in eroding blanket peatlands......Page 118
4.4.5 Sediment yield, sediment supply and assessing catchment erosion status......Page 120
4.5 Conclusions......Page 122
5.1 Introduction......Page 123
5.2.1 Limits to the stability of peat on slopes......Page 127
5.2.2 Creep on peat hillslopes......Page 130
5.3 Morphology of Rapid Peat Mass Movements......Page 131
5.3.1 Source zone......Page 134
5.3.3 Runout track......Page 135
5.3.4 Secondary tension and compression features......Page 137
5.3.5 Bog burst and peat slides – are they different?......Page 139
5.4 Mechanism of Peat Failure......Page 142
5.5 Significance of Surface Hydrology in Peat Failures......Page 144
5.5.1 Water content, pore pressures and volume changes......Page 146
5.5.3 Slope drainage......Page 147
5.6 Stability Analysis and Modelling of Peat Mass Movements......Page 148
5.7 The Changing Frequency of Peat Mass Movements Over Time......Page 150
5.8 Summary and Overall Framework......Page 152
6.1 Introduction......Page 155
6.2 The General Significance of Wind Erosion in Upland Peatlands......Page 156
6.3 Mechanisms and Processes of Wind Erosion......Page 159
6.4 Direct Measurements of Wind Erosion of Peat......Page 165
6.5 Significance of Dry Conditions and Drought for Wind Erosion......Page 169
6.6 Conclusions......Page 172
7.1 Rationale and Introduction......Page 174
7.2 Macroscale – Region/Catchment Scale......Page 177
7.3 Mesoscale – Slope Catena Scale......Page 181
7.4 Microscale – Material Structure Scale......Page 184
7.5 Linking the Geomorphological and the Ecohydrological......Page 186
7.6 Conclusions......Page 188
8.1 Introduction......Page 190
8.2 The Effect of Peatland Dynamics on Long-Term Sediment Budgets......Page 191
8.3.1 Artificial re-vegetation of bare peat surfaces......Page 193
8.3.2 Natural re-vegetation of eroded landscapes......Page 194
8.4.1 Extrinsic controls on re-vegetation......Page 197
8.4.2 Intrinsic controls on re-vegetation......Page 200
8.4.3 Eriophorum spp. as keystone species for re-vegetation of eroded peatlands......Page 204
8.4.4 Re-vegetation dynamics and long-term patterns of erosion......Page 206
8.5 Stratigraphic Evidence of Erosion and Re-Vegetation......Page 207
8.7 Changes in Pollution......Page 209
8.8 Climate Change Impacts......Page 210
8.8.1 Increased summer drought......Page 211
8.8.2 Increased winter rainfall intensity......Page 212
8.8.5 Overall response of the peatland system......Page 213
8.9 Relative Importance of Peat Erosion in Wider Upland Sediment Budgets......Page 214
8.10 Conclusions......Page 216
9.2 Upland Peatland Erosion and Carbon Budgets......Page 218
9.2.1 Case study example: the Rough Sike carbon budget......Page 220
9.3 Release of Stored Contaminants from Eroding Peatlands......Page 224
9.4.1 Frameworks for restoration......Page 228
9.4.2 Approaches to restoration......Page 229
9.4.3 Implications of the landsystems model and sediment budget work for restoration......Page 230
9.5.1 The nature of upland peatlands......Page 233
9.5.2 Geomorphological processes in upland peatlands......Page 234
9.5.3 The future of upland peatlands......Page 235
9.5.4 Representativeness of the peatland system model......Page 236
References......Page 238
Index......Page 270