Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1976 Diffusion of Sediment in the Lee of Dune-Like Bedforms. (Volumes I and II). Chinmoy Chakrabarti Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Chakrabarti, Chinmoy, "Diffusion of Sediment in the Lee of Dune-Like Bedforms. (Volumes I and II)." (1976). LSU Historical Dissertations and Theses. 3006. https://digitalcommons.lsu.edu/gradschool_disstheses/3006 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. INFORMATION TO USERS This material was produced from a microfilm copy of the original document. 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University Microfilms International 300 North Zeeb Road Ann Arbor, Michigan 48106 USA St, John's Road, Tyler's Green High Wycombe, Bucks, England HP10 8HR 77-10,358 CHAKRABARTI, Chinmoy, 1943- DIFFUSION OF SEDIMENT IN THE LEE OF DUNE-LIKE BEDFORMS. (VOLUMES I AND II) The Louisiana State University and Agricultural and Mechanical College, Ph.D., 1976 Geology Xerox University Microfilms, Ann Arbor, Michigan 48106 DIFFUSION OF SEDIMENT IN THE LEE OF DUNE-LIKE BEDFORMS VOLUME I A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy m The Department of Geology by Chinmoy Chakrabarti B.Sc.(Hons.), Jadavpur University, 1962 M.Sc., Jadavpur University, 1964 December, 1976 ACKNOWLED GEMENT I am grateful to the members of my examining committee, Drs. J. M. Coleman, P. H. Jones, D. R. Lowe, J. P. Morgan, and R. H. Pilger for critically reading the manuscript. Dr. Lowe went through several drafts of the dissertation and has been most helpful with constructive suggestions. Dr. Morgan arranged for the experimental work and helped in many ways in carrying it out. His critical reading has improved the quality of presentation of this dissertation. I am deeply indebted to the authorities of the Water­ ways Experimental Station, U. S. Army Corps of Engineers, Vicksburg, Mississippi for facilitating the experimental work. Mr. James Glover, Chief, Waterways Branch, and Mr. Tom Pokrefke, project engineer, WES, gave me invaluable assistance in the experimental design. I am indebted to the Director General, Geological Survey of India for granting me leave of absence for carrying out this work. My program was sponsored and initially financed jointly by the U. S. Educational Foundation in India and the Institute of International Education. I acknowledge with thanks the financial assist­ ance provided by the Department of Geology and the Student Government Association of Louisiana State University, and the Sigma Xi to complete my study. Institute of Inter­ national Education also provided funds for finalization of the dissertation. Finally, I am indebted to my wife, Champa, for moral support through many trying circumstances. iii TABLE OP CONTENTS Page VOLUME I ACKNOWLEDGEMENTS................................... ii LIST OF TABLES ...................................... v LIST OP F I G U R E S ................................... vi LIST OF APPENDICES.......... x ABSTRACT.............................................. xii INTRODUCTION........................................ 1 DEPOSITION RATE AND SIZE DISTRIBUTION IN GRAIN SETTLED SEDIMENT........................... 8 Theory ............................................ 8 Numerical Analysis ............................... 23 Experiments ...................................... 65 SIZE DIFFERENTIATION IN AVALANCED SEDIMENT........... 116 T h e o r y .......... 116 Experiments ........................................ 125 CONCLUSIONS .......................................... 166 REFERENCES............................................ 169 VOLUME II APPENDICES .......................................... 173 VITA .................................................. 401 iv LIST OP TABLES Page Table 1. Flow conditions for the experiments 17 to 2 7 ................................. 82 Table 2. Calculated values of the coefficient, c_,s in the deposition rate gradient regression equations ..................... 99 Table 3. Calculated values of the constant, b, in the deposition rate gradient equation................................. 99 Table 4. Values of the co-efficients a* and n* from the mean size gradient regression equations ..................... 101 Table 5. Flow conditions for experiments 2 to 16 137 v LIST OF FIGURES Determination of stream depth by the inverse path line method ........ 4 Principle elements of reattaching half-jet ............................. 22 Flow chart outlining the main steps in the numerical simulation program 26 Friction-factor predictor for flat­ bed flows in alluvial channels - . 28 The threshold of sediment movement as a function of the boundary Reynolds Number ..................... 30 Extrapolated curves for dimensionless measures of median path length and logarithmic standard deviation of dimensionless measures of starting height ............................... 32 Effect of sorting of bed material on simulated mean size gradient of the leeside sediment ................. 38 Effect of sorting of bed material on simulated mean size gradient of the leeside sediment ................. 40 Effect of sorting of bed material on simulated mean size gradient of the leeside sediment ................. 43 Effect of sorting of bed material on simulated mean size gradient of the leeside sediment ................. 43 Effect of sorting of bed material on simulated mean size gradient of the leeside sediment ................. 46 vi Effect of sorting of bed material on simulated deposition rate gradient of the leeside sediment . 52 Effect of sorting of bed material on simulated deposition rate gradient of the leeside sediment . 54 Effect of sorting of bed material on simulated deposition rate gradient of the leeside deposit . 56 Effect of the mean size of the bed material on the simulated deposition rate gradient of the leeside deposit . 60 Effect of the mean size of the bed material on the simulated deposition rate gradient of the leeside deposit . 62 Photograph of the Temperature Control Flume Facility of the U.S. Waterways Experiment Station, Vicksburg, Mississippi ................. 67 Schematic diagram of the flume used for experimentation ............... 69 End view of the sand feeder system of the flume looking downstream . 72 Diagram of the bedform modelled on the flume floor and of the sediment collector ............................. 75 Size frequency diagrams of sediment used as bed stock in the flume experiments ........................... 80 Deposition rate gradient of grain settled sediment for experiments 20 and 21 using the bed material of sand 1 ................................. 85 vii Page Figure 23. Experimental deposition rate plotted against distance from the dune crest using bed material from sand 2 . 87 Figure 24 Experimental deposition rate plotted against distance from the dune crest using bed material from sand 3 . 89 Figure 25. Experimental deposition rate plotted against distance from the dune crest using bed material from sand 4 . 91 Figure 26. Graphs showing the variation of relative weight concentration as probability percentage with distance from the crest of the dune for experiments with sand 1 and sand 2 . 94 Figure 27 Diagram showing the variation of relative weight concentration