Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies, School of 1-1-2011 From Hillslopes to Canyons, Studies of Erosion at Differing Time and Spatial Scales Within the Colorado River Drainage Christopher Tressler Utah State University Recommended Citation Tressler, Christopher, "From Hillslopes to Canyons, Studies of Erosion at Differing Time and Spatial Scales Within the Colorado River Drainage" (2011). All Graduate Theses and Dissertations. Paper 1109. http://digitalcommons.usu.edu/etd/1109 This Thesis is brought to you for free and open access by the Graduate Studies, School of at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. FROM HILLSLOPES TO CANYONS, STUDIES OF EROSION AT DIFFERING TIME AND SPATIAL SCALES WITHIN THE COLORADO RIVER DRAINAGE by Christopher Tressler A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Geology Approved: ________________________ ________________________ Joel L. Pederson Brian D. Collins Major Professor Committee Member ________________________ ________________________ John D. Rice Tammy M. Rittenour Committee Member Committee Member ____________________ Mark R. Mclellan Vice President for Research and Dean of the School of Graduate Studies UTAH STATE UNIVERSITY Logan, Utah 2011 ii ABSTRACT From Hillslopes to Canyons, Studies of Erosion at Differing Time and Spatial Scales Within The Colorado River Drainage by Christopher Tressler, Master of Science Utah State University Major Professor: Dr. Joel L. Pederson Department: Geology This thesis includes two different studies in an attempt to investigate and better understand the key characteristics of landscape evolution. In the first study, the rate of surface particle creep was investigated through the use of Terrestrial lidar at an archaeological site in Grand Canyon National Park. The second study developed ways to quantify metrics of the Colorado River drainage and reports the role of bedrock strength in the irregular profile of the trunk Colorado River drainage. Archaeological sites along the Colorado River corridor in Grand Canyon National Park are eroding due to a variety of surficial processes. The nature of surface particle creep is difficult to quantify and managers of this sensitive landscape wish to know the rates of erosion in order to make timely decisions regarding preservation. In the first study, two scans of a single convex hillslope iii were collected over the span of 12 months through the use of a ground-based lidar instrument. The scans were used to track the movement of rock clasts. This study, with a relatively small data set, did not show the expected positive relations of creep rate to slope or clast size, but did not preclude the existence of these relations either. The remarkably irregular long profile of the Colorado River has inspired several questions about the role of knickpoint recession, tectonics, and bedrock in the landscape evolution of Grand Canyon and the region. Bedrock resistance to erosion has a fundamental role in controlling topography and surface processes. In this second study, a data set of bedrock strength data was compiled and presented, providing relations of bedrock strength to hydraulic- driving forces of the trunk Colorado River drainage. Results indicate that rock strength and topographic metrics are strongly correlated in the middle to lower reaches of the plateau drainage. In the upper reaches of the drainage, intact-rock strength values are ~25% higher without a matching increase in stream power. As more tensile strength samples are analyzed and appropriately scaled with respect to fracturing and shale content, we believe we will see a clearer and more consistent pattern in the upper reaches. (109 pages) iv ACKNOWLEDGMENTS I would like to thank my advisor, Joel Pederson, for his encouragement and advice and for helping me grow as a scientist. My committee members, Brian Collins, John Rice, and Tammy Rittenour, provided their time and thoughtful comments, for which I am grateful. Todd Parr and Jesse King provided assistance with GIS and rock coring. Brian Dierker provided logistical support that allowed me to obtain data upstream of Hite. I thank the Utah State University Geology Department and the Grand Canyon Monitoring and Research Center for financial funding through research and teaching assistantships. I also thank the Geological Society of America for a student research grant. Finally, I would like to thank my wife, Susie, who has supported me in all of my educational endeavors. Christopher Tressler v CONTENTS Page ABSTRACT ...........................................................................................................ii ACKNOWLEDGMENTS .......................................................................................iv LIST OF TABLES ............................................................................................... viii LIST OF FIGURES...............................................................................................ix CHAPTER 1. INTRODUCTION............................................................................. 1 2. USING TERRESTRIAL LIDAR TO UNDERSTAND AND QUANTIFY SURFACE-PARTICLE CREEP AT ARCHAEOLOGICAL SITES IN GRAND CANYON......................... 3 ABSTRACT .......................................................................... 3 INTRODUCTION.................................................................. 4 BACKGROUND.................................................................... 5 METHODS ......................................................................... 12 Lidar Data Collection ............................................... 12 Data Processing / Movement Detection................... 15 Meteorological Data Collection ................................ 18 RESULTS........................................................................... 18 Error / Detection Limit .............................................. 18 Rock Movement / Transport Rates .......................... 20 Meteorological Data................................................. 22 DISCUSSION..................................................................... 23 Field Observations................................................... 23 Evaluation of Creep Process ................................... 28 CONCLUSIONS ................................................................. 28 REFERENCES................................................................... 29 3. LARGE-SCALE METRICS OF THE COLORADO vi RIVER DRAINAGE IN THE COLORADO PLATEAU: THE HUNT FOR KNICKZONES AND THEIR MEANING ................................ 31 ABSTRACT ........................................................................ 31 INTRODUCTION................................................................ 32 BACKGROUND.................................................................. 35 Unit Stream Power................................................... 35 SL index................................................................... 36 ksn ............................................................................ 36 METHODS ......................................................................... 38 Unit Stream Power................................................... 38 Channel and Valley Widths...................................... 40 ksn ............................................................................ 42 Concavity................................................................. 43 RESULTS........................................................................... 44 Unit Stream Power................................................... 44 ksn ............................................................................ 46 Concavity................................................................. 50 DISCUSSION / CONCLUSIONS........................................ 51 REFERENCES................................................................... 53 4. COLORADO PLATEAU ROCK STRENGTH AND RIVER KNICKZONES—SPATIAL DATASETS RELATING ERODABILITY TO TOPOGRAPHIC METRICS............................ 57 ABSTRACT ........................................................................ 57 INTRODUCTION................................................................ 58 BACKGROUND.................................................................. 62 Bedrock Incision Processes..................................... 62 Graded Profile of Bedrock Streams ......................... 63 Colorado River as a Mixed Bedrock-Alluvial River ..................................................................... 64 Creation of the Colorado River Profile after Base level Fall....................................................... 64 METHODS ......................................................................... 66 vii Mechanical Reaches ............................................... 66 Study Sites .............................................................. 66 Methods of Measurement ........................................ 67 Statistical Analysis................................................... 69 RESULTS........................................................................... 69 DISCUSSION / CONCLUSIONS........................................ 76 REFERENCES................................................................... 79 5. SUMMARY...................................................................................