RIVER BANK EROSION IN THE MINNESOTA RIVER VALLEY A DISSERTATION SUBMITTED TO THE FACULTY OF THE UNIVERSITY OF MINNESOTA BY ANDREW C KESSLER IN PARTIAL FULFILLMENT OF THE REQUIERMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DR. SATISH C GUPTA DECEMBER 2015 © ANDREW C. KESSLER, 2015 ACKNOWLEDGMENTS I gratefully acknowledge the assistance that was provided over the years in completing this research by Blue Earth County Environmental Services Staff especially Scott Salisbury and Professor Susan Galatowitsch of Fish, Wildlife and Conservation Biology for their insights about early survey data; Ryan Mattke and the staff at the University of Minnesota, John R. Borchert Map Library for their help with the historical aerial photographs; and Greg Spoden and Pete Boulay of the State Climatologist Office of the Minnesota Department of Natural Resources for sharing the long-term climatic data. In addition, I’d like to acknowledge help from Ashley Grundtner, Melinda Brown, David Thoma, and Kari Wolf with field work and manuscript reviews. The original 2009 Lidar scan was jointly funded by the Minnesota Corn and Soybean Research and Promotion Councils. Remaining research projects were partially supported with funds from the Minnesota Corn Research and Promotion Council. I’d also like to acknowledge the tireless work of my major adviser Dr. Satish Gupta whose guidance made this research possible. Finally, I would like to acknowledge my wife Andrea and our three daughters for supporting me through this endeavor. i ABSTRACT Sediments remain one of the major causes of water quality impairments in the United States. Although soil erosion from agricultural lands has been viewed as the major source of sediment to rivers and lakes, in many watersheds, river banks are also contributing a significant amount of sediments to surface waters. Currently, limited research has been reported on the methods to quantify and to understand the causes and mechanisms that control river bank erosion. The research reported in this dissertation utilized emerging technologies and novel procedures to investigate (1) historic and modern rates of river bank erosion in the Blue Earth River Basin, a major source of sediment to the Minnesota River and Lake Pepin; (2) methods to delineate seeps (a major mechanism of bank sloughing) on the face of river banks and their impact on bank erosion; and (3) water retention capacity of depressional areas across the prairie pot hole regions of the Greater Blue Earth River Basin. The results of this research indicate that river bank erosion is and has been a major source of sediment in the Greater Blue Earth River Basin even before European immigrants began to settle in Minnesota; the return intensity from light detection and ranging (Lidar) can be used to delineate seepage areas on river banks and this along with lidar generated digital elevation model provides an opportunity to quantify seepage impacts on bank erosion; and the historic storage capacity of a prairie pothole landscape such as the Greater Blue Earth River Basin is relatively small (152 mm) and concentrated only in large depressions. This suggests that restoration of depressional areas will unlikely have a major impact on river flows without additional modifications. ii TABLE OF CONTENTS ACKNOWLEDGMENTS ............................................................................................................................................ i ABSTRACT ....................................................................................................................................................................ii TABLE OF CONTENTS ........................................................................................................................................... iii LIST OF TABLES ....................................................................................................................................................... vii LIST OF FIGURES ...................................................................................................................................................... x SYNOPS IS ....................................................................................................................................................................... 1 LIDAR QUANTIFICATION OF BANK EROSION IN BLUE EARTH COUNTY, MINNESOTA ................. 2 ASSESSMENT OF RIVER BANK EROSION IN SOUTHERN MINNESTOA RIVERS POST EUROPEAN SETTLEMENT............................................................................................................................................................. 3 QUANTIFYING SEEPAGE CAUSED RIVER BANK EROSION USING LIDAR ........................................... 4 DRAINAGE IMPACTS ON SURFICIAL WATER RETENTION CAPACITY OF A PRAIRIE POTHOLE WATERSHED .............................................................................................................................................................. 4 CHAPTER 1: INTRODUCTION ............................................................................................................................. 6 QUANTIFICATION OF BANK EROSION ............................................................................................................ 7 HISTORIC RATES OF BANK EROSION ............................................................................................................... 9 MECHANISMS OF BANK EROSION ...................................................................................................................10 QUANTIFYING DEPRESSIONAL STORAGE ....................................................................................................11 THESIS STRUCTURE OVERVIEW ......................................................................................................................12 REFERENCES ..........................................................................................................................................................13 CHAPTER 2: LIDAR QUANTIFICATION OF BANK EROSION IN BLUE EARTH COUNTY, MINNESOTA ...............................................................................................................................................................18 SUMMARY .................................................................................................................................................................18 INTRODUCTION .....................................................................................................................................................19 MATERIALS AND METHODS...............................................................................................................................25 iii Study Area Description ....................................................................................................................................... 25 Lidar Data .............................................................................................................................................................. 29 Lidar Data Processing ......................................................................................................................................... 31 Lidar Data Accuracy............................................................................................................................................ 33 Fieldwork and Laboratory Analysis.................................................................................................................. 36 RESULTS AND DISCUSSION ...............................................................................................................................38 Accuracy Assessment of Lidar .......................................................................................................................... 38 Volume Change in River Valleys...................................................................................................................... 39 Contributions from Tall vs. Short Banks ......................................................................................................... 41 LDmin Uncertainty Analysis................................................................................................................................ 42 Spatial Interpolation............................................................................................................................................. 44 Characteristics of Stream Bank Sediments ...................................................................................................... 46 Fine Sediment, Soluble P and Total P Losses ................................................................................................. 48 Sensitivity Analysis of Fine Sediment, Soluble P and Total P Losses ....................................................... 53 CONCLUSIONS ........................................................................................................................................................55 REFERNCES .............................................................................................................................................................56 CHAPTER 3: ASSESSMENT OF RIVER BANK EROSION IN SOUTHERN MINNESTOA RIVERS POS T EUROPEAN S ETTLEMENT ...................................................................................................61 SUMMARY .................................................................................................................................................................61