DOCSLIB.ORG

Fluvial Processes in Motion: Measuring Bank Erosion And

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Fluvial Processes in Motion: Measuring Bank Erosion And University of Vermont ScholarWorks @ UVM Graduate College Dissertations and Theses Dissertations and Theses 2018 Fluvial Processes in Motion: Measuring Bank Erosion and Suspended Sediment Flux using Advanced Geomatic Methods and Machine Learning Scott ouD glas Hamshaw University of Vermont Follow this and additional works at: https://scholarworks.uvm.edu/graddis Part of the Computer Sciences Commons, Environmental Engineering Commons, and the Hydrology Commons Recommended Citation Hamshaw, Scott ouD glas, "Fluvial Processes in Motion: Measuring Bank Erosion and Suspended Sediment Flux using Advanced Geomatic Methods and Machine Learning" (2018). Graduate College Dissertations and Theses. 827. https://scholarworks.uvm.edu/graddis/827 This Dissertation is brought to you for free and open access by the Dissertations and Theses at ScholarWorks @ UVM. It has been accepted for inclusion in Graduate College Dissertations and Theses by an authorized administrator of ScholarWorks @ UVM. For more information, please contact [email protected]. FLUVIAL PROCESSES IN MOTION: MEASURING BANK EROSION AND SUSPENDED SEDIMENT FLUX USING ADVANCED GEOMATIC METHODS AND MACHINE LEARNING A Dissertation Presented by Scott D. Hamshaw to The Faculty of the Graduate College of The University of Vermont In Partial Fulfilment of the Requirements For the Degree of Doctor of Philosophy Specializing in Civil and Environmental Engineering January, 2018 Defense Date: September 12, 2017 Dissertation Examination Committee: Donna M. Rizzo, Ph.D., Advisor Andrew W. Schroth, Ph.D., Chairperson Mandar M. Dewoolkar, Ph.D. Beverley C. Wemple, Ph.D. Arne Bomblies, Ph.D. Jarlath O’Neil-Dunne, M.S. Cynthia J. Forehand, Ph.D., Dean of the Graduate College ABSTRACT Excessive erosion and fine sediment delivery to river corridors and receiving waters degrade aquatic habitat, add to nutrient loading, and impact infrastructure. Understanding the sources and movement of sediment within watersheds is critical for assessing ecosystem health and developing management plans to protect natural and human systems. As our changing climate continues to cause shifts in hydrological regimes (e.g., increased precipitation and streamflow in the northeast U.S.), the development of tools to better understand sediment dynamics takes on even greater importance. In this research, advanced geomatics and machine learning are applied to improve the (1) monitoring of streambank erosion, (2) understanding of event sediment dynamics, and (3) prediction of sediment loading using meteorological data as inputs. Streambank movement is an integral part of geomorphic changes along river corridors and also a significant source of fine sediment to receiving waters. Advances in unmanned aircraft systems (UAS) and photogrammetry provide opportunities for rapid and economical quantification of streambank erosion and deposition at variable scales. We assess the performance of UAS-based photogrammetry to capture streambank topography and quantify bank movement. UAS data were compared to terrestrial laser scanner (TLS) and GPS surveying from Vermont streambank sites that featured a variety of bank conditions and vegetation. Cross-sectional analysis of UAS and TLS data revealed that the UAS reliably captured the bank surface and was able to quantify the net change in bank area where movement occurred. Although it was necessary to consider overhanging bank profiles and vegetation, UAS-based photogrammetry showed significant promise for capturing bank topography and movement at fine resolutions in a flexible and efficient manner. This study also used a new machine-learning tool to improve the analysis of sediment dynamics using three years of high-resolution suspended sediment data collected in the Mad River watershed. A restricted Boltzmann machine (RBM), a type of artificial neural network (ANN), was used to classify individual storm events based on the visual hysteresis patterns present in the suspended sediment-discharge data. The work expanded the classification scheme typically used for hysteresis analysis. The results provided insights into the connectivity and sources of sediment within the Mad River watershed and its tributaries. A recurrent counterpropagation network (rCPN) was also developed to predict suspended sediment discharge at ungauged locations using only local meteorological data as inputs. The rCPN captured the nonlinear relationships between meteorological data and suspended sediment discharge, and outperformed the traditional sediment rating curve approach. The combination of machine-learning tools for analyzing storm-event dynamics and estimating loading at ungauged locations in a river network provides a robust method for estimating sediment production from catchments that informs watershed management. CITATIONS Material from this dissertation has been published in the following form: Hamshaw, S. D., Bryce, T., Rizzo, D. M., O'Neil‐Dunne, J., Frolik, J., & Dewoolkar, M. M.. (2017). Quantifying streambank movement and topography using unmanned aircraft system photogrammetry with comparison to terrestrial laser scanning. River Research and Applications. doi: 10.1002/rra.3183 AND Material from this dissertation has been submitted for publication to Geomatics, Natural Hazards, and Risk on October 31, 2017 in the following form Hamshaw, S.D., Engel, T., Rizzo, D.M., O’Neil-Dunne, J., & Dewoolkar, M. M.. (2017). Application of unmanned aircraft system (UAS) for monitoring bank erosion along a river corridor. Geomatics, Natural Hazards and Risk. AND Material from this dissertation has been submitted for publication to Hydrological Processes on November 5, 2017 in the following form Hamshaw, S.D. and Rizzo, D.M.. (2017). Predicting river suspended sediment loadings using hydrometeorological variables and counterpropagation neural networks. Hydrological Processes. AND Material from this dissertation has been submitted for publication to Water Resources Research on November 13, 2017 in the following form Hamshaw, S.D., Dewoolkar, M.M., Schroth, A.W., Wemple, B.C., and Rizzo, D.M.. (2017). A new machine-learning approach for classifying hysteresis in suspended-sediment discharge relationships using high-frequency monitoring data. Water Resources Research. ii ACKNOWLEDGEMENTS This body of research would not have been possible nor successful without the assistance, guidance, and encouragement from many people. I would like to first acknowledge my committee for their guidance, encouragement, and interest during the development of this dissertation. Thank you to Andrew Schroth, Jarlath O’Neil-Dunne, Arne Bomblies, and Beverley Wemple –your research endeavors at UVM are the reason why UVM is an inspiring place to do research. Thanks to my unofficial co-advisor Mandar Dewoolkar, whose support and knowledge in my research was greatly appreciated and whose combination of positive attitude and efficient approach made finishing this dissertation possible. Finally, a special thank you to my advisor, Donna Rizzo, who was unwavering in offering guidance, encouragement, and who, no matter the seemingly impossible deadlines, was dedicated to giving valuable feedback. In the fifteen years I have known her at UVM, she has been continuously committed to supporting in achieving my personal and career goals, and it was no different with supporting my teaching and research during my PhD program. I was fortunate to be able to work with many terrific undergraduate interns and fellow graduate students in conducting this research and it would not have been possible without them. Thank you to interns Alex Morton, Hanna Anderson, Kira Kelley, Anna Waldron, Jordan Duffy, Nathalie Simoes, and Wimara Rubia Sa Gomes for their help in collecting field data. Sincere thanks to fellow graduate students Thomas Bryce, Jody Stryker, Justin Guilbert, John Hanley, Nikos Fytilis, and Ian Anderson for their collaboration and contributions in data collection and feedback on project design. A special thank you to Kristen Underwood whose collaboration was especially valued during project design, data collection and analysis phases. iii A number of programs and labs at UVM provided support for this project, in particular for field data collection. Thank you to EPSCoR RACC project staff Katie Chang, Janel Roberge, Saul Blocher, and Pat Clemins for their work on testing water quality samples and supporting data management. The UVM Spatial Analysis Lab (SAL), and in particular Tayler Engel and the UAS team, contributed significantly to data collection and processing. I would also acknowledge the contributions from Beverley Wemple, Jeff Frolik, Don Ross, and Breck Bowden’s labs and their many graduate students and interns that I collaborated with on fieldwork and data collection. I am especially grateful for the contributions of a number of people in the larger community that both helped guide this research and made it possible to undertake. A number of landowners in the Mad River Valley were remarkably accommodating of having myself and other students setting up monitoring stations on their property and helping to keep it safe. Thanks to the Friends of the Mad River for their support of all the UVM research undertaken in the Mad River Valley. This research would not have been possible without the funding and support provided by the National Science Foundation (NSF), Vermont EPSCoR, the Vermont Water Resources and Lake Studies center, and the Robert and Patricia Switzer Foundation. Finally, thank you to my friends and family who both supported
Load more

Recommended publications
  • Measurement of Bedload Transport in Sand-Bed Rivers: a Look at Two Indirect Sampling Methods
    Published online in 2010 as part of U.S. Geological Survey Scientific Investigations Report 2010-5091. Measurement of Bedload Transport in Sand-Bed Rivers: A Look at Two Indirect Sampling Methods Robert R. Holmes, Jr. U.S. Geological Survey, Rolla, Missouri, United States. Abstract Sand-bed rivers present unique challenges to accurate measurement of the bedload transport rate using the traditional direct sampling methods of direct traps (for example the Helley-Smith bedload sampler). The two major issues are: 1) over sampling of sand transport caused by “mining” of sand due to the flow disturbance induced by the presence of the sampler and 2) clogging of the mesh bag with sand particles reducing the hydraulic efficiency of the sampler. Indirect measurement methods hold promise in that unlike direct methods, no transport-altering flow disturbance near the bed occurs. The bedform velocimetry method utilizes a measure of the bedform geometry and the speed of bedform translation to estimate the bedload transport through mass balance. The bedform velocimetry method is readily applied for the estimation of bedload transport in large sand-bed rivers so long as prominent bedforms are present and the streamflow discharge is steady for long enough to provide sufficient bedform translation between the successive bathymetric data sets. Bedform velocimetry in small sand- bed rivers is often problematic due to rapid variation within the hydrograph. The bottom-track bias feature of the acoustic Doppler current profiler (ADCP) has been utilized to accurately estimate the virtual velocities of sand-bed rivers. Coupling measurement of the virtual velocity with an accurate determination of the active depth of the streambed sediment movement is another method to measure bedload transport, which will be termed the “virtual velocity” method.
    [Show full text]
  • Geomorphic Classification of Rivers
    9.36 Geomorphic Classification of Rivers JM Buffington, U.S. Forest Service, Boise, ID, USA DR Montgomery, University of Washington, Seattle, WA, USA Published by Elsevier Inc. 9.36.1 Introduction 730 9.36.2 Purpose of Classification 730 9.36.3 Types of Channel Classification 731 9.36.3.1 Stream Order 731 9.36.3.2 Process Domains 732 9.36.3.3 Channel Pattern 732 9.36.3.4 Channel–Floodplain Interactions 735 9.36.3.5 Bed Material and Mobility 737 9.36.3.6 Channel Units 739 9.36.3.7 Hierarchical Classifications 739 9.36.3.8 Statistical Classifications 745 9.36.4 Use and Compatibility of Channel Classifications 745 9.36.5 The Rise and Fall of Classifications: Why Are Some Channel Classifications More Used Than Others? 747 9.36.6 Future Needs and Directions 753 9.36.6.1 Standardization and Sample Size 753 9.36.6.2 Remote Sensing 754 9.36.7 Conclusion 755 Acknowledgements 756 References 756 Appendix 762 9.36.1 Introduction 9.36.2 Purpose of Classification Over the last several decades, environmental legislation and a A basic tenet in geomorphology is that ‘form implies process.’As growing awareness of historical human disturbance to rivers such, numerous geomorphic classifications have been de- worldwide (Schumm, 1977; Collins et al., 2003; Surian and veloped for landscapes (Davis, 1899), hillslopes (Varnes, 1958), Rinaldi, 2003; Nilsson et al., 2005; Chin, 2006; Walter and and rivers (Section 9.36.3). The form–process paradigm is a Merritts, 2008) have fostered unprecedented collaboration potentially powerful tool for conducting quantitative geo- among scientists, land managers, and stakeholders to better morphic investigations.
    [Show full text]
  • Sedimentation and Shoaling Work Unit
    1 SEDIMENTARY PROCESSES lAND ENVIRONMENTS IIN THE COLUMBIA RIVER ESTUARY l_~~~~~~~~~~~~~~~7 I .a-.. .(.;,, . I _e .- :.;. .. =*I Final Report on the Sedimentation and Shoaling Work Unit of the Columbia River Estuary Data Development Program SEDIMENTARY PROCESSES AND ENVIRONMENTS IN THE COLUMBIA RIVER ESTUARY Contractor: School of Oceanography University of Washington Seattle, Washington 98195 Principal Investigator: Dr. Joe S. Creager School of Oceanography, WB-10 University of Washington Seattle, Washington 98195 (206) 543-5099 June 1984 I I I I Authors Christopher R. Sherwood I Joe S. Creager Edward H. Roy I Guy Gelfenbaum I Thomas Dempsey I I I I I I I - I I I I I I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFACE The Columbia River Estuary Data Development Program This document is one of a set of publications and other materials produced by the Columbia River Estuary Data Development Program (CREDDP). CREDDP has two purposes: to increase understanding of the ecology of the Columbia River Estuary and to provide information useful in making land and water use decisions. The program was initiated by local governments and citizens who saw a need for a better information base for use in managing natural resources and in planning for development. In response to these concerns, the Governors of the states of Oregon and Washington requested in 1974 that the Pacific Northwest River Basins Commission (PNRBC) undertake an interdisciplinary ecological study of the estuary. At approximately the same time, local governments and port districts formed the Columbia River Estuary Study Taskforce (CREST) to develop a regional management plan for the estuary. PNRBC produced a Plan of Study for a six-year, $6.2 million program which was authorized by the U.S.
    [Show full text]
  • 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design
    Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design Dan Cenderelli USDA Forest Service 1 Stream Systems Technology Center April 2009 5-1 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design Acknowledgements Traci Sylte, P.E. Bob Gubernick, P.E. Hydrologist, Engineering Geologist, Lolo NF, Montana Tongass NF, Alaska 2 April 2009 5-2 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design Presentation Outline • Watershed Context • Discharge and Channel Characteristics • Channel Characteristics and Fluvial Processes • Channel slope • Channel shape, confinement, entrenchment • Channel planform • Channel slope, shape, and planform • Channel-bed material • Channel bedforms • Channel Classifications • Understanding and Predicting Channel Adjustments/Responses 3 April 2009 5-3 USDA-FS: Wayne NF, Eastern Region Ohio Department of Transportation Designing for Aquatic Organism Passage at Road-Stream Crossings 5. Fluvial Processes and Channel Characteristics Important in Stream Simulation Design Feb 2003 Presentation Objectives • A better understanding and appreciation of channel features, fluvial processes, and channel dynamics at a Culvert Characteristics road-stream crossing. • built in late 1950’s • diameter 1.83 m • length 27 m • gradient 2.1 percent June 2007 • Understand the importance of integrating fluvial geomorphology with engineering principles to design a road-stream crossing that contains a Replacement Culvert Characteristics •Bottomless Structure natural and dynamic channel •Span: 5.49 m; Height: 2.25 m through the structure.
    [Show full text]
  • Some Characteristics of Fluvial Processes in Rivers
    Some Characteristics of Fluvial Processes in Rivers William W. Emmet t*. Luna B. Leopold** and Robert M. Myrick*** Abstract Fluvial processes in rivers have been studied extensively in the United States during the past 20 years. This paper relates some older studies of scour and fill to some new studies for which detailed data on water-surface slopes and bedload-transport rates help to substantiate earlier interpretations. Although discussion is based on data from three small rivers, the principles involved have transfer value to other rivers. Reversal in maximum values of water-surface slope from riffles during low flow to pools during high flow causes a similar reversal in maximum values of stream power; this reversal is reflected in measured values of bedload-transport rate. Both pool and riffle reaches are likely to contribute sediment to bedload, resulting in generalized scour during high flow. However, spatially-variable bedload-transport rates require those reaches with the least available stream power during times of high transport rate to temporarily fill as continuity in the sediment budget is maintained. Similarly, those reaches with the least available stream power during times of receding river stage become sinks for storage of the moving sediment. This process helps explain the sorting mechanism of sediment and the maintenance of pool-riffle sequences in rivers. The volume of scoured material within its annual travel distance is, on average, equal to annual bedload. but this is only an approximation because all bed particles do not move at the same speed or travel the same distance. Scour is associated with dilation of the grain bed through the scour depth, but individual particles move intermittently and at a speed much less than that of the water.
    [Show full text]
  • Understanding Braided River Landform Development Over Decadal Time Scale: Soil and Groundwater As Controls on Biogeomorphic Succession
    Unicentre CH-1015 Lausanne http://serval.unil.ch RYear : 2016 Understanding braided river landform development over decadal time scale: soil and groundwater as controls on biogeomorphic succession. Bätz Nico Bätz Nico, 2016, Understanding braided river landform development over decadal time scale: soil and groundwater as controls on biogeomorphic succession. Originally published at : Thesis, University of Lausanne Posted at the University of Lausanne Open Archive http://serval.unil.ch Document URN : urn:nbn:ch:serval-BIB_CB468C1D42D59 Droits d’auteur L'Université de Lausanne attire expressément l'attention des utilisateurs sur le fait que tous les documents publiés dans l'Archive SERVAL sont protégés par le droit d'auteur, conformément à la loi fédérale sur le droit d'auteur et les droits voisins (LDA). A ce titre, il est indispensable d'obtenir le consentement préalable de l'auteur et/ou de l’éditeur avant toute utilisation d'une oeuvre ou d'une partie d'une oeuvre ne relevant pas d'une utilisation à des fins personnelles au sens de la LDA (art. 19, al. 1 lettre a). A défaut, tout contrevenant s'expose aux sanctions prévues par cette loi. Nous déclinons toute responsabilité en la matière. Copyright The University of Lausanne expressly draws the attention of users to the fact that all documents published in the SERVAL Archive are protected by copyright in accordance with federal law on copyright and similar rights (LDA). Accordingly it is indispensable to obtain prior consent from the author and/or publisher before any use of a work or part of a work for purposes other than personal use within the meaning of LDA (art.
    [Show full text]
  • Monitoring of Bed Load Transport Within a Small Drainage Basin in the Polish Flysch Carpathians
    Published online in 2010 as part of U.S. Geological Survey Scientific Investigations Report 2010-5091. Monitoring of Bed Load Transport Within a Small Drainage Basin in the Polish Flysch Carpathians Wojciech Froehlich HOMERKA Laboratory of Fluvial Processes Institute of Geography and Spatial Organization, Polish Academy of Sciences, Nawojowa, Poland. Abstract The work reported in this contribution was undertaken in the Homerka instrumented catchment in the Polish Flysch Carpathians, where different techniques for monitoring sediment transport have been applied over the past 35 years. Bedload transport has been measured using both acoustic and magnetic techniques. The detection and measuring/registration units were made by the author and developed step-by-step and improved over the years. They are still experimental and have inherent advantages and limitations. The passive acoustic method permits continuous measurement and is able to provide a continuous record of coarse particle movement during flood events. Coarse material bedload transport has also been measured using magnetic tracers technique and electromagnetic sensors were used to track their movement through a designated short reach. Transport distances associated with individual gravel particles tagged with magnets during individual events have been documented by recovering after the event using a metal detector. The measuring techniques used at the Homerka instrumented catchment provided detailed and long-term records of temporal and spatial distribution of gravel transport during floods. Key words: gravel bedload, acoustic geophone, magnetic tracer, Homerka catchment 1.0 Introduction The work reported in this contribution was undertaken in the Homerka instrumented catchment in the Polish Flysch Carpathians, where different techniques for monitoring sediment transport have been applied over the past 35 years (see Froehlich, 1982, 2003).
    [Show full text]
  • Chapter 12 Dryland Rivers: Processes and Forms
    Chapter 12 Dryland Rivers: Processes and Forms D. Mark Powell Introduction phologies, and the fact that many of the forms are shared by rivers that drain other climatic zones, it is far Dryland alluvial rivers vary considerably in charac- from clear how far dryland rivers can be categorised as ter. In terms of processes, high energy, sediment-laden a distinctive group and whether such a categorisation flash floods in upland rivers contrast dramatically with provides a suitable basis for developing an understand- the low sediment loads and languid flows of their low- ing of them. On this basis, rather than attempt to under- land counterparts while from a form perspective, the stand dryland rivers as a distinctive and definable group unstable wide, shallow and sandy braid plains of pied- of rivers, this chapter seeks explanations for the charac- mont rivers are quite different from the relatively sta- ter (the diversity, distinctiveness and, in some cases, the ble, narrow, deep and muddy channels of anastomosing uniqueness) of dryland rivers in terms of the operation systems (Nanson et al. 2002). It is also apparent that of geomorphological processes as they are mediated by few, if any, morphological features are unique to dry- the climatic regime. Because the multivariate and in- land rivers. The variety of dryland river forms and the determinate nature of river channel adjustment makes absence of a set of defining dryland river characteristics it difficult to describe directly the three-dimensional makes it difficult to generalise about dryland rivers and subtleties of channel form, the chapter follows the ap- raises questions about whether it is necessary (or even proach of Ferguson (1981) and concentrates on three desirable) to consider dryland river systems separately separate two-dimensional views in turn: the channel from those in other climatic zones.
    [Show full text]
  • Literature Review on Methods of Measuring Fluvial Sediment, By
    Methods of Measuring Fluvial Sediment by Lisa Fraley Graduate Research Assistant Center for Urban Environmental Research and Education University of Maryland, Baltimore County 1000 Hilltop Circle Technology Research Center 102 Baltimore, MD 21250 January 21, 2004 1 Contents Page 1. Sediment and the Fluvial Environment …………………………………………….3 2. Study Area…….…………………………………………………………………….4 3. Particle Size Distributions…….…………………………………………………….6 3.1 Surface Sampling ………..……………….………………………….…...8 3.1.1 Wolman Pebble Count…………………………………………...8 3.2 Volumetric Sampling……………………………………………………..9 3.2.1 Bulk Cores..……………………………………………………10 3.2.2 Freeze Cores…………………………………………………...12 4. Suspended Sediment……………………………………………………………...13 4.1 Depth Integrating Sampler………………………………………………15 4.1.1 DH-81………………………………………………………….15 4.1.2 DH-59 and DH-76……………………………………………..16 4.1.3 D-74 and D-77…………………………………………………16 4.2 Point Integrating Sampler………………………………………………..17 4.2.1 P-61 and P-63……………………………...…………………..18 4.2.2 P-72……………………………………………………………19 4.3 Single Stage Samplers…………………………………………………...19 5. Bed Material Load………………………………………………………………...21 5.1 Helley-Smith……………………………………………………………..24 5.2 Pit Traps………………………………………………………………….26 5.3 Tracer Grains……………………………………………………………..27 5.4 Sediment Transport Equations……………………………….…………..29 5.5 Bedload Traps…………………………………………….………………31 6. Changes in Sediment Storage……………………………………………………..32 6.1 Aerial Photograph Analysis……………………………………………...33 6.2 Cross Sections……………………………………………………………34 6.3 Scour Chains……………………………………………………………..34 6.4 Measurement of Fine Sediment in Pools………………………………...35 7. Sediment Sampling Methods Applicable to Valley Creek………………………..37 7.1 Particle Size Distribution………………………………………………...37 7.2 Suspended Sediment……………………………………………………..38 7.3 Bed Material Load……………………………………………………….40 7.4 Changes in Sediment Storage……………………………………………41 2 Methods of Measuring Fluvial Sediment 1. Sediment and the Fluvial Environment As erosional and depositional agents, rivers are the cause of major landscape modification.
    [Show full text]
  • Chapter 4 Transport of Sediment by Water
    I Contents Symbols ................................................................................. 4-1 I Terms ................................................................................... 4-3 General ................................................................................. 4-4 Factors affecting sediment transport ......................................................... 4-4 Characteristics of water as the transporting medium .......................................... 4-4 Laminarsublayer ....................................................................... 4-4 Characteristics of transportable materials ................................................... 4-5 Mechanism of entrainment ................................................................. 4-5 Forces acting on discrete particles .......................................................... 4-5 Tractiveforce ........................................................................... 4-5 Determining critical tractive stress ......................................................... 4-6 Determining critical velocity .............................................................. 4-6 Hydraulicconsiderations ................................................................... 4-8 Fixedboundaries ........................................................................ 4-8 Movableboundaries ...................................................................... 4-8 Movement ofbedmaterial .................................................................. 4-9 Schoklitschformula
    [Show full text]
  • Fluvial Landforms & Processes
    Fluvial Landforms & Processes River Systems and Fluvial Landforms Longitudinal Profile and Equilibrium Drainage Basins, classic patterns Lakes and Dams Mountain Streams Straight Rivers Braided Rivers Meandering Rivers Anabranching Rivers Gulleys River Terraces Waterfalls Photo: SCGS Flood plains Alluvial Fans 1 Fluvial Landforms & Processes Rivers are one of the most dominant agents of landscape change Flowing waters are continually eroding, transporting, and depositing sediments (Fluvial Processes). River based flooding is among one of the most frequent and widespread natural hazards. 2 Longitudinal Profile and Watersheds longitudinal profile: an elevation cross-section of the entire watershed from the source of flowing water to the mouth of the stream. headwaters: the highest elevation where water collects to form a stream network. base level: the lowest elevation that a stream can erode its channel. Local or temporary base levels may be formed by reservoirs or waterfalls. Headwaters 3,000 Ultimate Base level Elevation (feet) 0 100 0 River Length (Miles) 3 Longitudinal Profile and Watersheds A river’s gradient (slope) is steepest near the headwaters and gentlest near the mouth. As rivers flow from their headwaters to their base level they carve valleys into the landscape by eroding, transporting, and depositing weathered rocks, soil, and sediment. Headwaters more erosion 3,000 more deposition Ultimate Base level Elevation (feet) 0 100 0 River Length (Miles) 4 Fluvial Equilibrium • Stream gradient is related to water velocity and sediment load • A change in any of these affects the other two. • base level fluctuations (gradient) • precipitation changes (discharge) • sediment character Fluvial Equilibrium Recent uplift in excess of erosional rates results in a system that is out of equilibrium.
    [Show full text]
  • Fluvial Processes with Special Emphasis on Glacial Rivers
    Section 3 FLUVIAL PROCESSES WITH SPECIAL EMPHASIS ON GLACIAL RIVERS An Annotated Bibliography Compiled for the Region II FRPA Riparian Management Science & Technical Committee by Jason E.B. Mouw Alaska Department of Fish and Game, Sport Fish Division SUMMARY Glacial rivers are perhaps some of the most physically diverse ecosystems on earth and are characterized by tremendous habitat complexity that shifts in space and time at a wide variety of scales. They are characterized by a highly variable flow regime and extreme suspended sediment concentrations (Milner and Petts, 1994). Glacial rivers typically adopt one or both of two general channel forms: braided or anastomosed. Braiding is typically referred to as the channel state in which splitting channels flow around bars or islands that are contained between dominant floodplain banks. Anastomosis refers to a split channel form in which multiple channels flow around rather permanent vegetated islands that are not flooded at bankfull discharge. Braided rivers are characterized by relatively high stream power (due to a high channel slope), high rates of erosion, deposition, and channel change. Anastomosing rivers are characterized by lower channel slope gradients, and perhaps higher rates of deposition. In general, glacial rivers flow with cold water, yet due to their aquatic habitat complexity they are characterized by high thermal heterogeneity (Malard et al. 2001) that supports a wide variety of fish species and their various life history stages and strategies. This physical habitat complexity is driven by cut and fill alluviation. These fluvial processes are driven by bank erosion and lateral and point bar accretion. Though the cause of channel form in glacial systems is still debated, there are several important factors that contribute.
    [Show full text]