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Durham E-Theses Signicance of Bedrock Channel Morphology and Sediment Dynamics in a U.K. Upland River. Smith, Hazel Marie How to cite: Smith, Hazel Marie (2004) Signicance of Bedrock Channel Morphology and Sediment Dynamics in a U.K. Upland River., Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/2976/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk 2 Significance of Bedrock Channel Morphology and Sediment Dynamics in a U.K. Upland River. A copyright of this thesis rests with the author. No quotation from it should be published without his prior written consent and information derived from it should be acknowledged. Hazel Marie Smith MSc (Research) Department of Geography 2004 University Of Durham 1 Abstract Bedrock channels in the uplands of the U.K. are widespread but their geomorphology and sedimentology have rarely been studied. The aim of this research is to determine rates and processes of sedimentation in an upland bedrock channel following a large flood event. The main field site is a 300 m bedrock reach of Trout Beck in the Upper Tees drainage basin, Northern England. Sedimentary processes are investigated using morphological evidence (channel cross section surveys, repeat photography and geomorphic mapping) and field tracing of coarse bedload. The significance of the channel processes operating in the study reach are evaluated by mapping the extent of bedrock channel features in the upper Tees catchment. Flume experiments are also undertaken to supplement field data collected in rock step surveys. In the Upper Tees catchment, bedrock channels form 20% of the upland stream network, 10% of channels consist of bare rock with no sedimentation. The stream network was divided into five channel classes from bedrock (1) through to fully alluvial (5). In both Trout Beck and the Upper Tees bedrock channel sections gradual transitions from bedrock to fully alluvial reaches and back again were common. Equally, however very abrupt changes at the end of fully alluvial or bedrock channel section could often be found (e.g. transitions 1-5 and 5-1). Classification of the river channel using this scheme allowed the local importantance of bedrock channel landforms on hydraulic conditions and sedimentation processes to be described. In the study reach both lateral sedimentation and amalgamation of sediment bars were observed as mechanisms of re-sedimentation. The rate and location of sedimentation is controlled by local hydraulics (rock steps), gradient and discharge. The tracer study supports the assumption that sediment movement in river channels is episodic. The rock step survey demonstrated the large variability in the shape and size of these features and their important influence on the hydraulics of the flow. 2 Acknowledgements Firstly a great deal of thanks goes to my supervisor Jeff Warburton and his family, for encouraging me to research the topic of bedrock rivers and also for his endless availability and support. Secondly a big thank you to all the technical staff, Michelle Allan in the computer laboratories and Derek Coates, Eddie Million, Brian Priestley and Neil Tunstall in the research laboratories for their expertise in the building of equipment and their patience and assistance when preparation of field material. A lot of respect and thanks for all who assisted me in obtaining the results in the cold and wet days on Moor House. To Matt Brain who provided an optimistic view of Moor House in the rain and a rising bedrock channel, to Mike Hardbattle whose assistance in the wind was invaluable and the only person to achieve a suntan at Moor House. To Sarah Clement thank you for the company on Moor House travelling to and from fieldwork together and for all your help in measuring and surveying all those cross sections. To Alona and Duncan whose assistance and knowledge helped me to produce the geomorphic maps and survey the many cross sections accurately. Finally to my family and friends for all the support they have given me over the past year and a half, many thanks to you all. 3 Contents Page Title Page 1 Abstract 2 Acknowledgements 3 Contents 4 List of Figures 7 List of Tables 11 Declaration 12 Chapter 1 -Introduction and Study Area 1.1 Introduction 13 1.2 Background 13 1.3Aim 13 1 .4 Objectives 14 1 . 5 Location of the Study Area 15 1.6 River systems of the area 20 1.7 Geology and Topography 21 1.8 Landscape Evolution 25 1.9 River development 26 1.1 0 Climate 27 Chapter 2 - Literature Review 2.1. Scope of chapter 29 2.2. Bedrock Channel Classification 29 2.3. Significance of the study scale 33 2.4 Channel morphology 35 2.5 Landforms of bedrock erosion 36 2.5.1 Knickpoints 38 2.5.2 Gorges 39 2.5.3 Cascades 40 2.5.4 Step-pool channel 40 2.5.5 Plane-bed channels 42 2.5.6 Small scale landforms 44 - 4- Contents 2.6 Erosional Landform production 45 2. 7 Flow dynamics and hydraulics 45 2.8 Sediment transport 48 2.9 Flume studies 51 2.10 Research in the U.K. uplands 52 Chapter 3 - Field and Laboratory Methods 3.1 Introduction 54 3.2 Geomorphic Mapping 54 3.3 Channel Cross Sectional Survey 58 3.4 Fixed Point Photography 59 3.5 Sediment grain-size surveys 60 3.6 Tracers 61 3.7 Bedrock Channel Classification 66 3.8 Flume Experiments 67 3.9 Summary 70 Chapter 4- Results of Sedimentation Changes 4.1 Introduction 71 4.2 Channel Cross section Surveys 71 4.3 Fixed Point Photography 76 4.4 Geomorphic mapping 83 4.5 Sediment sample surveys 87 4.5.1 Sediment grain-size analysis on selected cross sections 87 4.5.2 Sediment grain-size analysis on selected bars 87 4.6 Tracers 90 4.6.1 Long Profile 90 4.6.2 Stage Data 90 4.6.3 Tracer events 93 4.7 Influence of a bed step 96 4.8 Rock step data 99 4.9 Summary 102 - 5 - Contents Chapter 5- Results : Bedrock Stream Classification 5.1 Introduction 104 5.2 Classification of the Tees and Trout Beck 104 5.3 Classification of the Tees 106 5.3.1 Upper Tees 106 5.3.2 Middle Tees 106 5.3.2.1 Upper middle Tees 108 5.3.2.2 Lower middle Tees 108 5.3.3 Trout Beck (Section 4) 111 5.3.4 Middle Trout Beck 111 5.3.5 Lower Trout Beck 113 5.3.6.Lower Tees 113 5.4 Analysis of bedrock channel type transitions 116 5.5 Markov chain analysis 120 5.6 Distribution of class reach lengths 122 5.7 Lengths of bank classes in Trout Beck and the Tees 123 5.8 Summary 124 Chapter 6 - Discussion 6.1 Introduction 125 6.2. Sedimentation at the reach scale 125 6.3 Classification of bedrock rivers on a basin scale 135 Chapter 7 - Conclusion 7.1 Conclusion 140 7.2 Limitations 142 7.3 Extensions of current research 143 Chapter 8- References 8.1 References 145 - 6- List of Figures Page Figure 1.1 Location map showing the location of the study area within 15 Northern England and the Northern Pennines. Figure 1.2 Illustration of the upper section of the study reach 17 Figure 1.3 Middle of study reach, end of gorge section 17 Figure 1.4 End of bedrock section of study reach, many small eroisional 17 bedrock features and joint structures are visible. Figure 1.5 Map of study reach and the Upper Tees and Trout Beck 19 catchments areas Figure 1.6 Geology of study Area (Source: British Geological Survey 22 Alston - England and Wales Sheet 25 Soild drift Edition (1973). Figure 1.7 Regional geological section and main structural elements of 23 Northern England. (Based on Taylor eta/. 1971 ). Figure 1.8 High Force Upper Teasdale 22 m drop into a wide bedrock 24 gorge, the waterfall provides a classic example of a knickpoint Figure 2.1 The bedrock channel system (Warburton, 2003 37 Unpublished). Figure 2.2 Knickpoint just above the Weir on Trout Beck 39 (Upstream, NY75749, 33471 ). Figure 2.3 High Force Aerial view 43 Figure 2.4 South Tyne bedrock plane bed sequence 43 Figure 2.5 Cladew step-pool sequence 43 Figure 2.6 Small scale bedrock features in Trout Beck within the study 44 reach Figure 2.7 Build up of fine sediment on the bedrock plane of the Trout 49 Beck study reach Figure 3.1 Integration of the methodologies used in the research 55 Figure 3.2 Detailed fieldwork plan 56 Figure 3.3 Geomorphic map illustrating the cross section and fixed 57 photography points (20/11/02). Figure 3.4 Methodology for the state logger. 64 List of Figures Figure 3.5 A comparison of the size distribution of the tracers used in 65 the study and the bar located at the tracer introduction point.