STREAM BANK EROSION TRENDS AND SEDIMENT CONTRIBUTIONS IN A SOUTHWESTERN MISSOURI RIVER A Masters Thesis Presented to The Graduate College of Missouri State University In Partial Fulfillment Of the Requirements for the Degree Master of Science, Geospatial Sciences in Geography, Geology, and Planning By Ezekiel Kuehn July 2015 STREAM BANK EROSION TRENDS AND SEDIMENT CONTRIBUTIONS IN A SOUTHWESTERN MISSOURI RIVER Ezekiel Kuehn Geography, Geology, and Planning Missouri State University, July 2015 Masters of Science ABSTRACT Bank erosion can be a significant source of in-stream sediment that negatively affects water quality and aquatic habitat. However, assessments of the role that eroding banks play in suspended and bed sediment supply are rarely available to managers. The purpose of this study was to quantify bank erosion rates for a 7 km conservation easement the James River in southwest Missouri to evaluate the annual contributions of bank sediment to the channel. The objectives were to: (1) monitor an eroding 260 m bank to better understand short-term, reach scale bank erosion rates; (2) determine historical rates of bank erosion for the entire riparian easement using aerial photographs from 1952, 1997, and 2008; and (3) determine the contribution of bank erosion to annual river sediment loads and in-channel gravel storage. The erosion rates of fine sediment from historical aerial photograph analysis averaged 210 Mg/yr/km. Bank erosion contributions to suspended sediment loads in the James River ranged from 16% to 50%. Bank erosion along the James River is often limited by bedrock outcrops which can protect banks, increase channel stability, and reduce sediment supply. However, flow disturbance zones at channel bends along bedrock bluffs can enhance bar formation locally which can force lateral channel shifting and increased bank erosion rates. KEYWORDS: stream bank erosion, sediment transport, geographic information system, fluvial geomorphology This abstract is approved as to form and content _______________________________ Robert T. Pavlowsky Chairperson, Advisory Committee Missouri State University ii STREAM BANK EROSION TRENDS AND SEDIMENT CONTRIBUTIONS IN A SOUTHWESTERN MISSOURI RIVER By Ezekiel Kuehn A Masters Thesis Submitted to the Graduate College Of Missouri State University In Partial Fulfillment of the Requirements For the Degree of Master of Science, Geospatial Sciences in Geography, Geology, and Planning July 2015 Approved: _______________________________________ Dr. Robert T. Pavlowsky _______________________________________ Dr. Jun Luo _______________________________________ Dr. Xiaomin Qiu _______________________________________ Dr. Julie Masterson, Dean, Graduate College iii ACKNOWLEDGEMENTS First and foremost I would like to thank Dr. Pavlowsky for his patience and advice during my time as a graduate student at MSU. I would also like to thank Dr. Luo and Dr. Qiu for their time and advice as my committee members. A special thank you goes out to Marc Owen for his guidance and answering my never ending questions about GIS, field methods, and everything else. I would also like to acknowledge OEWRI for letting so many other students and myself obtain experience while helping us through Graduate College. I would like to thank my parents for bestowing upon me a love for the natural world, and supporting me through every step of my life. I would like to thank my beautiful wife Tiffany Kuehn for her unwavering support and patience during my years as a graduate student. I could not have done it without her. iv TABLE OF CONTENTS Introduction ..........................................................................................................................1 Causes of Bank Erosion ............................................................................................2 Geomorphic Processes Controlling Bank Erosion ....................................................5 Contribution to Sediment Loads ...............................................................................7 Sediment Loads and Bank Contributions in the Ozark Highlands .........................10 Purpose and Objectives ...........................................................................................11 Benefits of Study.....................................................................................................14 Study Area .........................................................................................................................16 Regional Location ...................................................................................................16 Geology ...................................................................................................................20 Climate ....................................................................................................................22 Land Use Past and Present......................................................................................24 Soils.........................................................................................................................23 Hydrology ...............................................................................................................25 Methodology ......................................................................................................................29 Site Selection and Study Design ..............................................................................29 Geomorphic Field Assessments ...............................................................................31 Erosion Pin Array Monitoring .................................................................................32 Segment Scale Bank Erosion Rates .........................................................................35 GIS Aerial Photograph Analysis ..................................................................35 Calculation of Bank Erosion Rates ..............................................................38 Sediment Volume and Mass Calculations ...................................................39 Bar Sediment Storage ..............................................................................................41 James River Sediment Loads ...................................................................................42 Determining Bank Full Discharge ...........................................................................45 Results & Discussion .........................................................................................................47 Reach-Scale Bank Erosion Pin Trends ....................................................................47 Erosion Pin Monitoring ...............................................................................47 Bank Sediment Loss ....................................................................................51 Segment Scale Bank Erosion Trends .......................................................................55 Bank Erosion Rates ......................................................................................55 River Bank Conditions .................................................................................62 Bank Sediment inputs to the James River....................................................66 Bar Distribution and Storage .......................................................................71 Bank Erosion Relationships .....................................................................................72 Fine Sediment Composition .........................................................................72 Valley Morphology and Channel Pattern ....................................................73 Bank Contributions to Sediment Loads in the James River ....................................76 Fine Sediment Contributions .......................................................................76 v Bank Erosion Contribution to the Gravel Bars in the James River .............78 Causes of Bank Erosion in the James River ...........................................................84 Hydrologic Factors........................................................................................84 Geomorphic Influences .................................................................................84 Channel Planform ........................................................................................85 Bar Deposition and Forcing ..........................................................................85 Geologic Factors ...........................................................................................91 Vegetation .....................................................................................................91 Evaluation of Bank Sediment Sources in the Ozarks .............................................92 Fine Sediment ...............................................................................................92 Coarse Sediment ...........................................................................................93 Study Limitations ....................................................................................................95 Conclusion .........................................................................................................................97 References ........................................................................................................................101 Appendicies .....................................................................................................................109