THE POOL-RIFFLE SEQUENCE AS THE PRINCIPAL DESIGN COMPONENT OF LOW-GRADIENT, MEANDERING, GMWL-BED CHANNELS A Thesis Presented to The Facdty of Graduate Studies of The University of Guelph by A.M. HARTLEY In partial filfilment of requirements for the degree of Master of Science Apnl, 1999 O A. Mark Hartley, 1999 National Library Bibliothèque nationale I*m of Canada du Canada Acquisitions and Acquisitions et Bibliographic Services services bibliographiques 395 Wellington Street 395. me Wellington OttawaON KIA ON4 Ottawa ON K1A ON4 Canada Canada Yow hk Votre referenca Our tüe Notre reldrence The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant a La National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sel1 reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or electronic formats. la forme de microfichelfilm, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fkom it Ni la thèse ni des extraits substantiels may be printed or othenvise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. ABSTRACT THE POOL-RLFFLE SEQUENCE AS THE PRINCIPAL DESIGN COMPONENT OF LOW-GRADIENT, MEANDERING GRAVEL-BED CHANNELS A. Mark Hartley, P.Eng. Advisor: University of Guelph, 1999 Dr. Hugh Whiteiey Channel design methods have recently been eqanded in Southem Ontario to consider the form and fuaction of channek observed in nature. These efforts have recognized sipifkant geomorphic (sinuosity, entrenchment, bedforms) and fish habitat features of a river. Recent case studies and design guidance documents recognize the three dimensional structure of rivers but the hydraulic properties are pooriy characterïzed. Bedforms provide a usefùr focal point for the characterization of geometric, fluvial as well as hydradic characteristics. Bedforms have a dominant effect on the variables used in the standard-step backwater equation during flows equal to or less than banl6ull stage. Measurements of these variables at the upstream and downstrearn ends of bedforms, in this case pools and riffles, were collected at one reach of the Credit River and one reach of Whitemans Creek. Results indicated that geomeûic (bed elevation) and fluvial (water depth, shear veIocity) characteristics were signifïcantly difEerent between nfEles and pools within a reach, between riBies of the two reaches and between pools of the two reaches. Hydraulic characteristics (grain and form energy losses) were not significantiy Werent due to high variabiliv and low sarnple number. The energy-Ioss coefficient may be as high a 2.0 and is rareIy Iess that 1.5. A design procedure far pool-rime sequences in low-gradient gravel-bed channels is presented as weii as recommendations for Mer work. This research has been a classical exercise in education by discovery and has been greatly enhancecl by several considerable contributions, both financial and scholastic. I would like to thank my Advisory Cornmittee, Drs. Whiteley, Dickinson and Kostaschuk for giving me the freedom to "explore the possibikties" yet not aUowing any significant deviations from what seemed to me to be a rnoving target. This thesis would not have been completed doutJudy7s gentle reminders and Peggy's endless patience, my reiiable "contacts" with the University; 1997 was a tough year - thanks for your help Thanks to Bill A~ablefor "showing me the ropes", teaching me the "Rosgen method" through the many, rnany long days spent in the field and evenings spent c'discussing the days workx and helping me to stay away fiom the "classical" channel design methodologies by stresshg ''let the rivsr teach us". The high qualis custorn-designed equipment bdt by the School of Engineering technical stafT, Paul and Bill, was critical to the collection of good field data; 1 couldn7thave done it without them. 1 would to thank Bill Snodgrass for dowing me the use of the velocity meter for such a long period of tirne. It's amazing what you can do with good equipment. Financial support was provided by the National Science and Engineering Research Council, the Grand River Conservation Authority and the American Fisheries Society - Southem Ontario Chapter. 1 greatly appreciate the assistance provided by the Grand River Conservation AuthorXty and the Credit Vdey Conservation for aiiowiag me access to the reaches within their watersheds. Last but not 1- words cannot begh to describe the shear volurne of unquestioning support, understanding and fkith provided by my de, Doina. When the water appeared the darkest and deepest, your soothing words, radiant srnile and gentle hand pulied me through. Dedicated to my parents, Norman Aiderson Hartley 1933 - 1997 Elizabeth Ann Hartiey 1933 - 1997 TABLE OF CONTENTS 1.0 INTRODUCTION ................. ....... ........... ...t ................................................................................. 1 2.0 BACKGROUND.......................................................................................................................... 5 2.1 DESIGMNGR~~TERC~ANNELS ............................... .... ..................................................................... 6 2.1.1 Recently Date loped Procedures................................................................................................... 6 2.1.2 Recent Channel Consh-uctiodRestorationEfforts ...................................................................... 12 2.2 R~VERCHANNELS AND CLASSIFICATIONSYSTEMS ............................................................................... 13 2.3 LARGESCALE CHARACTERISTICS OF RIVERS....................................................................................... 19 2.3.1 Physiography and River VaDeys ............................................................................................... 19 2.3.2 Meandering ofriver channeCs .................................................................................................... 21 2.3.3 Dominant Discharge .................................................................................................................. 23 2-4 MORPHOLOGYOF GRAVEL-BEDRTVERS ............................................................................................ 25 2.4.1 Bedforms in grave[-bed rivers - Rifles and Pools ...................................................................... 25 2.4.2 Physical Characteristics ofRzfles and Pools ............................................................................. 27 2.4.2.1 Longitudinal Dimensions................................................................................................................... 27 2.4.2.2 Cross Sectional Features ..................................................................................................................... 28 2.4.2.3 Bed Roughness.................................................................................................................................... 30 2.4.3 Fluvial Characteristics ofRifles and Pools .............................................................................. 32 2.4.3.1 Flow resistance ................................................................................................................................ 32 2.4.3.2 Energy Losses ..................................................................................................................................... 36 2.4.4 Env ironmentaf Sign~pcanceof Riffles and Pools: Fish Habitat .............................................. 39 3.0 STUDY OBJECTIVES................................................................................................................... 43 4.0 METHODOLOGY....................................................................................................................... 45 4.1 SmSELECTION ................................................................................................................................ 45 4.2 FIELDWORK ..................................................................................................................................... 48 3.2 1 Topographie Survey. .................................................................................................................. 51 4.2.2 Water SmceElmations ........................................................................................................... 52 ............................................................ 4.2.3 Veloci~Profiles ............................................................ 52 3.2.4 Substrate Particle Size ............................................................................................................... 53 4.3 DATAANALYSIS................................................................................................................................ 53 4.3.1 Flow Durution and Flood Frequency ......................................................................................... 53 43.2 Geomorphic Characteristics of Rifles & Pools .......................................................................... 53 43.3 Velocj~Distribution and Energy Losses .................................................................................... 54 5.0 RESULTS AND DISCUSSION ....................................................................................................