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Geomorphic Variation of a Transitional River: Blue Ridge to Piedmont, South Carolina Tanner Arrington University of South Carolina

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Geomorphic Variation of a Transitional River: Blue Ridge to Piedmont, South Carolina Tanner Arrington University of South Carolina University of South Carolina Scholar Commons Theses and Dissertations 1-1-2013 Geomorphic Variation of A Transitional River: Blue Ridge to Piedmont, South Carolina Tanner Arrington University of South Carolina Follow this and additional works at: https://scholarcommons.sc.edu/etd Part of the Geography Commons Recommended Citation Arrington, T.(2013). Geomorphic Variation of A Transitional River: Blue Ridge to Piedmont, South Carolina. (Master's thesis). Retrieved from https://scholarcommons.sc.edu/etd/1273 This Open Access Thesis is brought to you by Scholar Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. GEOMORPHIC VARIATION OF A TRANSITIONAL RIVER: BLUE RIDGE TO PIEDMONT, SOUTH CAROLINA by Tanner Arrington Bachelor of Arts The University of Texas at Austin, 2010 Submitted in Partial Fulfillment of the Requirements For the Degree of Master of Science in Geography College of Arts and Sciences University of South Carolina 2013 Accepted by: Allan James, Director of Thesis John Kupfer, Reader Ray Torres, Reader Lacy Ford, Vice Provost and Dean of Graduate Studies © Copyright by Tanner Arrington, 2013 All Rights Reserved. ii DEDICATION To my wife, Virginia, who worked to support our family as I completed this degree. iii ACKNOWLEDGMENTS I’d like to thank Dr. Allan James for advising me through the progress of this research. I would also like to thank Dr. John Kupfer and Dr. Ray Torres for serving on my committee and providing helpful feedback in preparation for the research. Thanks to Chris Kaase for being my right hand man during fieldwork. Also, the residents around the Middle Saluda River were very helpful in providing access to the river, good bar-b- que and places to stay during fieldwork. iv ABSTRACT Field data was collected systematically to characterize the geomorphic variations in a river transition from the southern Blue Ridge to the Piedmont physiographic regions in South Carolina. Ten study reaches were surveyed for cross-sections and longitudinal profiles. Surface grid samples of bed material collected. Downstream hydraulic geometry and downstream fining of bed material were analyzed using traditional power functions and exponential decay relationships. Reach-scale channel bed morphology (bedforms) was analyzed under the assumption that the transition in bedforms is related to changes in hydraulic geometry and sediment characteristics. Well-developed downstream trends of hydraulic geometry variables (width, depth and velocity) and bed material fining were observed. However, variations within the general trends reflect the influence of a key transition zone characterized by substantial tributary inputs, drastic decreases in slope, and the presence of erosion-resistant bedrock knickpoints. Bedforms were distinguished using a regime diagram, an approach that utilizes hydraulic and sediment data that is independent of drainage area. Plots of relative grain submergence (R/D84), relative form submergence (R/H), Darcy-Weisbach friction factor (f) and slope vs. area reveal trends in the data that are not discernible with downstream models. Hydraulic, sediment, and bedform data suggest that structurally controlled breaks in slope are influential to bedform characteristics, resulting in forced morphologies that v may not be distinguished using simple downstream models. This corroborates the utility of scale-independent methods, especially in mountain or transitional environments where fluvial controls may be longitudinally forced and sporadic. The results also support the perspective of antecedent landscape influences on channel processes and form. These results have implications for river management and restoration approaches in such environments, as scale-independent models and landscape-scale perspectives can be beneficial to management objectives. vi PREFACE The idea for this research was developed after noticing the apparently high level of interest in local rivers from land owners and citizens around the Middle Saluda River. Many fences and lawns display the yard-signs of local river interest organizations. Two recent river “restoration” projects have been completed in the area, on the Middle Saluda River in 2009 and the South Saluda River in 2011. Further, debates broke out between different groups over the restoration approach on the South Saluda, resulting in a lawsuit that attempted to halt the project. Debate about river restoration has been ongoing for well over a decade (see Bernhardt et al. 2007), with projects achieving varying degrees of “success”. While states like Maryland and North Carolina have completed large numbers of restoration projects, South Carolina joined river restoration activities relatively late. The author’s prior knowledge of the river restoration debate and the recent projects in the area were the foundations of the research interests in this thesis. vii TABLE OF CONTENTS DEDICATION ........................................................................................................................... iii ACKNOWLEDGMENTS ............................................................................................................... iv ABSTRACT ................................................................................................................................v PREFACE ............................................................................................................................... vii LIST OF TABLES .........................................................................................................................x LIST OF FIGURES ...................................................................................................................... xi CHAPTER 1 INTRODUCTION AND CONCEPTUAL FRAMEWORK ............................................................ 1 1.1 INTRODUCTION ...................................................................................................... 1 1.2 CONCEPTUAL FRAMEWORK ...................................................................................... 2 CHAPTER 2 SUBMITTED MANUSCRIPT .......................................................................................... 8 2.1 ABSTRACT ........................................................................................................... 10 2.2 INTRODUCTION .................................................................................................... 11 2.3 PHYSICAL SETTING ................................................................................................ 17 2.4 METHODOLOGY ................................................................................................... 19 viii 2.5 RESULTS ............................................................................................................. 24 2.6 DISCUSSION AND CONCLUSION ............................................................................... 35 2.7 REFERENCES ........................................................................................................ 39 CHAPTER 3 EXTENDED METHODOLOGY RESULTS AND DISCUSSION .................................................. 40 3.1 EXTENDED METHODS ............................................................................................ 40 3.2 EXTENDED RESULTS .............................................................................................. 49 3.3 EXTENDED DISCUSSION .......................................................................................... 54 CONCLUSION ......................................................................................................................... 57 REFERENCES .......................................................................................................................... 58 APPENDIX A – TABLES OF DATA ................................................................................................ 63 APPENDIX B – CROSS-SECTIONS AND BANKFULL PROFILES .............................................................. 68 ix LIST OF TABLES TABLE 2.1 EXPLANATION OF VARIABLES AND CALCULATIONS .......................................................... 23 TABLE 2.2 SUMMARY OF DATA AND CALCULATIONS ..................................................................... 24 TABLE 3.1 DOWNSTREAM TRENDS IN GRAPHIC ARITHMETIC STATISTICS ........................................... 52 TABLE A.1 BASIN DATA ........................................................................................................... 63 TABLE A.2 HYDRAULICS DATA .................................................................................................. 64 TABLE A.3 BED MATERIAL PARTICLE B-AXIS DIMENSIONS (MM) ..................................................... 65 TABLE A.4 GRAPHIC ARITHMETIC BED MATERIAL STATISTICS.......................................................... 66 TABLE A.5 INDICES AND RATIOS DATA ....................................................................................... 67 TABLE A.6 BEDFORM DATA ..................................................................................................... 67 x LIST OF FIGURES FIGURE 2.1 CONCEPTUAL BEDFORM TYPES ................................................................................. 16 FIGURE 2.2 STUDY WATERSHED LOCATION AND TOPOGRAPHY ....................................................... 19 FIGURE 2.3 DOWNSTREAM HYDRAULIC GEOMETRY RELATIONSHIPS ...............................................
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