THE POOL- 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 (, entrenchment, ) and fish features of a . Recent case studies and design guidance documents recognize the three dimensional structure of 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 , 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" 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 ...... 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 Frequency ...... 53 43.2 Geomorphic Characteristics of Rifles & Pools ...... 53 43.3 Velocj~Distribution and Energy Losses ...... 54 5.0 RESULTS AND DISCUSSION ...... 56 5.1 HYDROLOGICSE~G ...... 56 5.2 V.~LLEYAND REACH GEOMETRICCHARACTERISTICS ...... 63 5.3 GEOMETRICAND RUVIALCHARACTERISTICS OF POOLS GW RIFFLES ...... 64 5.4 HYDRAULICCHARACTERISTICS OF POOLS AND WS...... 71 5.5 POOL-- SEQUENCEAS THE PRINCPALDESIGN COMPONENT ...... 75 6.0 CONCLUSIONS & RECOMMZNDATIONS...... 80

7.0 REFERENCES ...... 82 APPENDIX A .CREDIT' RIVER DATA ...... 90 APPENDM B .-MANS CREEK DATA...... 125 LIST OF TABLES

TABLE1 . LIST OF DiFFERENT 'L"YPES AND THEiR RESPECTIVE BEDFORMS FEATURES AS DESCRIBED IN ROSGENSC~ASSIFICATION ...... 4 TABLE^. SUMMARYOFRIVERCLASSIFICATIONSYSTEMS...... 14 TABLE 3 . ROSGENSCLASSIFICATION SYSTEM HIGfILIGHTWG STREAM TYPES (C, E, F) WITH RIFFLE-POOL SEQvENCES...... 16 TABLE4. LIST OF VAEUABLES MEASURED BY hl3J~~l.E(1995) ...... 19 TABLE5. SUMMARYOF THE VARIABLES USED TO DEFINE RIFFLES AND POOLS ...... 27 TABLE 6 . m0 CASES DEMONSTRATING THE DIFFERENCES A!!ONGST THE B-F-M EXPONENTS BETWEEN RIFFLES AND POOLS...... 29 TABLE7 . RELATIONSHIPS USED TO INTERPET AT-A-STATION HYDRAULIC GEOMETRY...... 30 TABLE8. -E ~ODSOF CALCULATING ~GSN BASED ON WA~R DE~TH...... 35 T~LE9 . WGE OF COEFETCIENTS, x xw 8, FOR EQUAITON2.1 1...... 36 TABLE10 . SIXESSENTIAL CO-MPO~TXTS OF FISB HABiTAT- ...... 40 LE 11 . SUMMARY OF THE FLOW REGIME OF THE STUDY REACHES (ALL VALUES ARE d/~)...... 60 T.~BLE12 . SUMMARY OF OCCASIONS WHEN VELOCRY AND WATER LEVEL DATA WERE COLLECTED AT THE STUDY REACHES (ADF = AVERAGE DAILY FLOW, bf3/s, FDA% = PERCENTAGE OF TIME WHEN DALY FLOW WAS EQUALED OR MCEEDED) ...... 63 TABLE13 . S-Y OFREACH CWCTERISTICS ...... 64 TABLE14 . BEDAND WATER SURFACE SLOPES FOR RlFFLES AND POOLS IN THE STUDY REACHES (ALLVALUES REPORTED AS %) ...... 65 TABLE15 . SUBSTRATEPART~CLE SIZES (MM) FOR RFFLES AND POOLS M THE STUDY REACHES ...... 67 TABLE16. LISTINGOF OCCASIONS WHEN VELOCITY DATA WERE COLLECTED AT SPECEDCROSS-SECTIONS WITHiN THE STUDY REACHES ...... 67 TABLE17 . . COMPARISONOF FLUVIAL AND HYDRAULIC VARIABLES BETWEEN POOLS AND RIFFLES AT EACH OF THE Sl"'LJDY REACHES (sIGNIFICANTLY DIFFERENT AT 95%, LARGER VALUES ARE SHADED)...... 68 TABLE 18. COMPARISONOF FLUVIAL AND HYDRAULlC VARIABLES BETWEEN THE STLiDY REACHES FOR POOLS AND FOR RIFFLES (SIGNIFICANTLY DEFEREUTAT 95%, LARGER VALUES ARE SHADED) ...... 69 TABLE 19. COMPARISONOF FLUVIAL AM) HYDRAULIC VARTABLES BETWEEN THE STUDY REACHES AND BETWEEN POOLS RiFFLES (Y MDICATES TEiERE WAS X SIGNIFICANT DIFFERENCE FOR THAT VARii\BLE w THAT CATEGORY) ...... 70 TABLE20 . COMPARISON OF THE ENERGY COEFFTCIENT, a,BETWEEN EUTLES AND POOLS ...... 7 1 TABLE 21. RELATIONSHIP BETWEEN CROSS-SECTION AND VELOCITY PRO= SHEAR kTLOCITY (FIGURE13.7 1 TABLE 22 . COMPARISONBETWEEN GRAIN ROUGHNESS, ROUGHNESS LENGTH AND MEDIAN PUTICLE SISE. (MEAN VALUES WITH RANGE IN BRACKETS, AU DIMENSION IN MM) ...... 73 TABLE23 . COMPARTSONBEWEEN THE SLOPES (Yo) OF THE HYDR4ULIC AND EXERGY GRADE LINES ...... 74 TABLE24 . SWMMARY OF THE AVERAGE TOTAL, GRAIN AND FORM HEAD LOSSES FOR IUFFLES AND POOLS IN THE SrUDY REACHES ...... 74 TABLE 25. VARIATIONIN HEAD LOSSES WITH AVERAGE DLULY FLOW FOR THE RIFFLES IN THE STLTDY REACHES (REMADJING RIFFLES AND ALL POOLS WERE NOT ViSïED AT HIGHER FLOWS) ...... 75 LIST OF FIGURES

FIGURE 1. SCHEMATICDIAGRAM OF RIFFLE-POOL SEQUENCE...... CCCC.C.CC.CC.CCCCCCCCCCCCCCCCCCCCCC.CCCCCC 26 FIGURE 2. CONCEPTUALDiAGW OF A POOL-RIFFLE SEQUENCE ILLUSTEWmG BED SLOPE VARIABLITY iWD H~DRAULICVARIABLES (D, = RESIDUAL DEPTH, EGL = ENERGY GRADE WNE, ffGL = HYDRAULIC GWE

LINE) ...-..--..-.....,.....-....--...-....--.*...... *-.-* ...... -...-...... 44 FIGURE 3. LOCATIONOF S~YREACH ON THE CREDITRIVER NEAR CATARACT...... --.---.- -.-..--.- .-....-. .-- 46

FIGURE4. LOCATIONOF STUDY REXK ON WID'IEMANSCREEK NE- APPS ...... -.. -.. - - SSSS. - - - - 47 FIGURE5. LOCATIONOF CROSS-SECTIONS mTHE R~VER REACH...... --. 49 FIGURE6. LOCATIONOF CROSS-SECTIONS TFIE WJ~ITEMANSCREEK REACH...... 50 FIGURE7. DISCRE~ATIONOF THE VELOCJTY MEXWREMENTS IN TFE CROSS-SECTION C'SED TO CaCULATE THE ENERGY COEFFICIENT. ., ...... , ...... -. . - - -.-. .-. .. . -. .-. -. - - -...... - - .. - -..-. .. - .- - .. . . - ..- .- -.- - - - -...... - . . 5 5 FIGURE8. mlE SERmS PLOT OF AVERAGE DALY FLOWS FOR WHITEMANSCREEK AND CREDITWR @ISCHARGE DATA OBTAINED FROM WSC GAUGES 02GB008 02HB00 1 RESPECT~VELY)...... - -.- -.-. 57 FIGURE9. FLOW DURATION CLrRVE FOR DAILY FLOWS FOR WHITEMANS CREEK(f) AND =DIT RIVER (O). FLOWDATA OBTAINED FROM WSC GAUGES 02GB008 AND 02m001 RESPECWLY). .. , . , ...... 58 FIGURE10. COMPMSONOF FLOOD FREQUENCY DISTRIBUTION OF ANNWAL MAXIMUM MSTANTANEOUS DISCHARGES BETWEEN WHITEMANSCREEK AND THE CRED!XRIVER (FLOW DATA OBTADV'ED FROM WSC GAUGES 02GBOO8 iLvD 02HB00 1 RESPECTWELY...... -..-.-.-.-.---.... .-..-...... ,,....-. 39 FIGURE 11. TIME SERIES PLOT OF AVEUGE DAILY FLOWS FOR THE -DIT RIVERILLUSTRAmG TIMES WHEN DATA WERE COLLECTED...... -...... -...--...... -.-.....---*..-- .-.....-...... -.-.~...... 6 1 FIGURE12. TWS SERIES PLOT OF AVERAGE DAILY FLOWS FORWHITEMANSCREEK iLLUSTRATING TIMES WHEN DATA WERE COLLECTED...... 62 FIGURE 13. LLNEARRELATIONSHIP (THROUGH THE ORIGIN) BETWEEN THE VELOCITY PROFILE SHEAR VELOCLT'Y AND THE CROSS SECTION SHEAR VELOCJTY...... -..-.-.-...---...... --.-.-.*...----.----.-. 72 FIGURE14. RECOMMENDEDDESIGN PROCEDURE FOR POOL-RFFL.E SEQUENCES IN LOW-GRADIENT GRAVEL- BED CHANNELS...... 77 FIGURE15. ~USTRATIONOF THE METK-IOD TO CONFIGURE AND DIMENSION THE POOL-RCFFLE SEQUENCE. .. 78 LIST OF SYMBOLS

Descp rition cross-section area area of local velocity cell slope of log-hear velocity prome regression coefficient for fiction factor constant intercept of log-linear velocity profile regression coefficient for friction factor width exponent eqansion/contraction coefficient average depth of water characteristic particle size residual depth particle size, 16% mer particle size, 50% liner particle size, 84% finer Darcy-Weisbach fiction factor depth exponent acceleration due to gravity head loss due to form roughness head loss due to grain roughness head loss due to expansion/contraction height of velocity cell total head at cross-section i total head loss between two cross-sections equivaient sand grain roughness fonn loss coefficient width of velocïty cell distance berneen tsvo cross-sections velocity exponent Marinings roughness factor discharge baddull discharge discharge hydraulic radius energy slope - average energy slope - form roughness energy slope - grain roughness local average Inter-pool bed gradient rime bed gradient water surface slope Iocal velocity Iocal shear velocity cross-section shear velocity average velocity Width flow depth verticle distance from bed roughnes height channel bed elevation Symbol Descp rition a energy coefficient Y specinc weight of water K vonKumen turbulence constant v kinematic viscosity P density of water

=O cross-section shear stress 1.0 INTRODUCTION The design of open channels has changed drarnaticaüy in recent years in Southem Ontario.

Impacts that channe1 works may have on the environment include, but are not Lirnited to, , soi1 , hydrauiics, geomorphoiogy, water cpahy, terrestrial biota, aquatic biota and Iocai socioeconomics (MT0 1997). When performing any type of work in and around channeis it has become common practice to consider these environmentai impacts and to design chamieis in such a manner as to minunize the impact of proposed works on the environment.

Numerous pieces of legislation, including but not limited to the federal Fisheries Act and the provincial Consemation Authorities Act, some requiring pre-constniction perrnits, may be applicable to a particular channel work. Many of these laws and regdations have environrnerrtal protection implications that require engineers to incorporate the complex spatial and temporal variab* of river systems into their designs of open channels. An engineer can no longer consider a channel cross-section to be reasombly uniform dong its length, for design purposes, as has been the case for many years.

Historical design criteria included conveyance of a design-storm discharge and the prevention of and bed erosion; both criteria were associated with the protection of public structures and public health and safi. Hardened channels of concrete, excessively large Stone, or any other rigid, immovable dcehave produced the following effects (Environment Canada

1994):

a loss of flshery and wildlife habitat, a of water qualrty and a loss of aesthetic features associated with a river or stream. a negative cumulative impact where multiple hardened channe1s have been constructd on the same river

shorter He spans than previously expected; muai maintenance has been necessary to rnaintain the structural integrity of the channel. The regdations under the Conservation Authorities Act irnply that the straightening or ditchuig of watercourses results in impacts on the hydrauiic characteristics & fïsheries resources and coasequently do not permit such works. The preferred alternative is the construct a channel that contains as many natural features as possible. The design criteria of flowrate capacity and channel stability are still valid but have recdy been expanded to include, on a broad sde, environment and human health, econornic contributors (other than least capital cost), liabihy and aesthetics

(MNR 1994). One spedic environmental criterion recently imposed and dorced on channel desigus is the prevention of the loss of fish habitat. This particular criterion has been deemed extremely siwcant since there is directly-applicable federal legislation, the Fisheries Act, tbat specifically states that it is an offense to hady-alter fish habitat. It is desirable, wherever possible, to maximk the natural features of a channel since they not ody contain fish habitat of high value, but also have high social value due to their inherent pleasing aesthetic qualities.

lmplicit in this environmental design approach is the ability of the channel designer to duplicate the physical characteristics that a comparable river reach would exhibit under natural conditions. In order to do this, an understanding of river chelform and funciion is necessary.

Two guidance documents have been prepared recently in Ontario in an attempt summarize the curent date of understanding of "natd channel systems": 'Watural Channel Systems: An

Approach to Management and Design" (MM 1994), and the revised "Drainage Management

Manual" (MT0 1997). The purpose of the former document is to "provide guidelines for a natural approach to chamel design and management". The recent revision of the latter document contains considerably more material on designing channels in erodible substrate than previous versions. In these documents it is not clear what roll each of the various disciplines such as engineering, biology or geomorphology should play in the design of natural channels. Inherent in these guidelines are the criteria for the protection and restoration of fish habitat.

It is recommended that several habitat features be included in the channel design process. They include spawning, nursery, rearing and food supply areas as well as the abllity for &h to migrate through the reach. But, despite the fact that the aforementioned sections discuss various features such as low-gradient riffles, , cascades, glides, backwater pools, channel pools and dammed pools (MT0 1997), there ranains a lack of morphologicaI, fluvial and sedimentological details on bedform features in these guidelines.

Considerable academic research has been conducted over the years (Schumm 1963,

KelIerhals et al. 1976, Mosley 1984 and Selby 1985) in an effort to understand fluvial forms and processes but this information has yet to be fùlly incorporated into the design process. In many cases, Stream degradation and the failed restoration efforts were both caused by an inadequate understanding of the natural characteristics of the Stream especially the patterns of water and that create and maintain the natural rnorphology of the channel and its associated (National Research Council 1992). The si@cant role of geomorphology in the understanding of river hction was initially presented in the 1960's (Leopold et al. 1964 and

Blench 1969) but did not appear in commonly accepted channel design practices. Recentiy these works are being re-evduated in recognition of its importance in the design process of river chels. In the last few years, more fûnctional river classification schemes have been proposed, including one by Rosgen (1 999, to aid the channel designer in satisfjmg the environmental criteria.

Rosgen's classification system includes nine different cheltypes (Aa+, A, B, C, D,

DA, E, F, G) each with up to six different substrate (bedrock, boulder, cobble, gravel, sand, silt/clay) delineation's. In this system, bedform features are an integral part of the river reach morphology uable 1). Among the Rosgen types of river channels studied by Amable (1995) the

most common was the Iow-gradient, meandering, gravel-bed channe1 (C4). This type of river has

extrernely high value for fish due to the strong correlation's among the characteristic bedfoq the

pool-rinle seqynce, the grave1 substrate and the abundance of high qu* fish habitat.

Table 1. List of different stream types and their respective bedfomsfeatures as described in Rosgens Classr~cation.

Type Bedform Aa+ step-pool morphology with chutes, debris flows and A step-pool morphology with Çequently spaced plunge or scour pools B "rapids" predominate with infrequently spaced sconr pools 1 C 1 meandering channel, rifne-pool morphology with characteristic point bars 1 D braided chamel, longitudinaYtransverse bars, closely spaced rapids-scour pools DA anastarnosed with well-vegetated bars E tortuous meandering channel, Mie-pool morphology F entrenched meandering channei, moderated rif2le-pool sequence G "millv" tme with steu-~oolseauence

The research results reported in this thesis respond to the need to examine the importance of bed- fonn features as a fùndamental aspect of naturally-occurring channels. Examination of bed-fonns in gravel-bed rivers is a high priority since these rivers are known to contain good quahty fish habitat. Once it bas been detennined htthe channel is a low-gradient, meandering, gravel-bed chamel, then funher guidance is required as to how the constnict the pool-rifne sequence. Specifically, the purpose of this research was:

to investigate the hypothesis that the pool-rifle sequence is the princÏpal design component of low-gradient, meandering gravel-b ed channels

Confirmation of this hypothesis would allow channel designers to estimate hydraulic condition through pool-rifle sequences of a gravel-bed river at flows les than bankfüil. and would &O provide a valuable linkage between the physical rquirements of fish habitat and the engineering design of river channels. These channels are expected to be stable and should re- rnany of the channel alignment problerns including excessive bend or bank erosion. 2.0 BACKGROUND There are many aspects to consider when descnbing and designing river channels, including the physical dimensions of the chamel, flow- frequency, energy dissipatioq sediment transport and erosion/. Since many of these aspects overlap, a logical hework such as spatiai scale could provide a structure within which a discussion may be set. One possible fiamework is a set of nested spatial scales that has the hydrologically-~ontributingcatchment as the upper limit of size and proceeds in decreasing size through the local segment to the local channel segment and finally to bedform feanires. River classification systerns apply to the valley segment scale and are commonly used to summarize the observed diverse patterns of river channels flowing withjn their respective valleys. This nested spatial scde may also prove useful in the channel design process as each of the above noted topics rnay be considered components of the overall river system. Accordingly this nested spatid scale formed the basis of the recent MNR

Guidance document (MNR 1994). The mallest practical scale of this bework is the bedfonn sequence that is commonly referenced to the channel width.

Sediment transport rnay also be used as a focal point for discussian of rivers and channel design. The sources and movement of sedunent and the relationship of sediment transport to channe1 form and fùnction is a complex topic and not discussed here. Sedinient ixmsport processes actually give rise to the channel structure, in this case pools and xfffles (Yang 197 lb, CIZEord

1993b). The focus herein shd be the three-dimensional forrn of a particular type of river at the scale of the bedform feature and the way in which water passes over these structures at discharge recurrence intervals less than those which cause sediment transport. 2.1.1 Recently Developed Procedures As noted previously, the two prirnary guidance documents for channe1 design in Southern

Ontario are 'Hatural Channel Systems: An Approach to Management and Design" (MNR 1994) and "'Drainage Management Manual" (MT01997). The earlier version of the latter document had a section on open channel design added in 1992 when the Ministry of Transport distributed

"Chapter C Open Channel Design" (MT0 1992). The work of Annable (1995) was intended to compliment the MNR Guidance document. Since his work presented data on Werent rather than discussiag design procedures: it M11 be discussed in later sections. Newbury and

Gabouy (1993) developed a field manual for Stream analysis and fish habitat design.

The 1992 edition of the MT0 Drainage Manuai describes in detail the methods for planning and designing open channels especially as they pertained to highway projects. The project planning and design process is sumrnarized as follows:

ldentify problem wtegory (runoff collection, Iining rehabilitation. realignment. diversions)

Set goals and objectives

Set criteria and guidelines

Oata collection and field investigation

Hydrologie and hydraulic estimates

Identify/ewluate/sel& alternatives

Prepare conceptual design

Detail design and final

The procedures outlined apply classical open channel hydraulic calculations to the problem of channe1 design and con& of sizing a channe1 to pass the regional flood without causing channel erosion. Some consideration was given to geomophological and biological components of the river systan. Bedfomis, such as rimes, pools and point bars, were defined and bnefly discussed but the description of their physical characteristics and their effects on the water dace profile was incomplete. Ody when fish habitat was a specific design criterion was it suggested to consider designhg a nfne-pool sequence. In developing this design, a limited nurnber of guidelines, such as obtahiq the dimensions of the plan fonn geometry fiom field investigations and aerial photography, were provideci as subjective design constraints. These dimensions included

Iength, meander wid- pool-ae length, pool Ien* width. depth and side dopes, and dfle

1engt.h width and depth, The process for rifile-pool design was to:

check for appropriateness of the rime-pool sequence;

size the subchannel;

layout the sequence (distance behnreen pools to be approximately 5-7 channel widths) and

sue the pools and riffies

Efield àata were not readily availabIe it was recommended to apply the following guideluies to size the pools and nffles:

pool-riffie spacing should be approximately 5-7 channel widths and regular spacing should be avoided

individual pools or riffies should not be longer than three channel widths or shorter than one channel width instream devices should:

be locafed and constnicted to minirnize upstream backwater for large streamflow events

be constructed to freely pass logs and debris

be able to withstand large sûearnflow events and be constmcted of natural materials

stream banks should be well protected if instream devices are used

in cases where the riffles are to be dynarnic and self-sustaining. they should be constnicted frorn natural stream grave1 with a size distribution typical of the exïsting bed rnaterial. RiMe material should not project above the bed by more than 0.3 to 0.5 rn

pools should have a minimum low-water depth of 0.3 rn and should be constnicted in ; asyrnmetric cross-sections that approdmate natural cross-sections are recommended; in general pools should be located on the outside of the watercourse bends.

Although the watershed contex-t of the river design phase is rnissing, the discussion on geomorphology provided some uisight into the need to consider more than just channel and floodplain cross-sections. This discussion happens to focus on a riffle-pool morphology and recommends against constructing this sequence in ephemeral , steep gradient streams,

strmwith bigh sediment transport loads, reaches with unstable banks or reaches where the bed

is armoured. It Ïs implied that ail rivers may be divided into sections of -es and pools.

Even if the riffIe-pool sequence was the proper seIection of channd form for the desired

channe1 there tvas considerable design data rnissing fiom this procedure which in tum would make

final design of the channel dBicult. In particular the longitudinal profile including the slopes of the

rï£Eles and pools and their relatiomhip to vdey and reach slopes was not dwcribed. Cross-section

dimensions were determined fkom field investigations. A compound double trapezoidal channel

was assumed to approximate a typical riffle and associated floodplain. The "lower or sub- channel

" was sized to pass the 2-year flow and the "upper channei" was sized to pus the

regional flood. It was also suggested that instream structures such as wing deflectors and

were necessary to maintain the nffle-pool system.

Shortly after the MT0 document was issued, a group of scientists and engineers convened

in Ontario to discuss several issues regarding channel design, including geomorphological and

ecological concepts initiaily presented in the 195OYs,and to detemine if these issues couid be addresseci by expanding the classical engineering design approach. The result of the group's efforts was presented in 1994 in the fom of a Guidance Document (MNR 1994). The purpose of this document was

to provide the procedures ?O folZow for selecting chunnel objectives and for the management and design process. It is not a provincial policy and not intended to be a technical cookbook. This document will provide information and a process for incorporating geomorphological and ecological considerutions to Stream and valley management and design. The technology and the physical relationships that can be used to design and manage naîural channel systerns are evolving. This document is provided with the recognition that the process and rnethodology applied should be flexible in order to adapt to this evolu tion. The approach presented recognized that there may be several design objectives including capacq requirements, erosion protection, public safety, fisheries habitat and recreational opportunities and that one or more of these objectives may be in conflict. A typical design process, such as the one discussed in the MT0 document, was adjusteci in an attempt to resclve potential design objective conflicts. This process was as follows:

Define objectives for design

Define existing conditions

Define expected natural regirne

Identify inconsistencies

Define design parameters for unconstrained design

ldentify constraints

Identify tradeoffs

Develop final design paramete=

Evaluate design

A sigmfïcant component of this process was the definition of existing conditions and cornparison to an expected naniral regirne. This task relied heavily on the Rosgen classification system (Rosgen

1995).

This design process was similar to the MT0 (1992) approach in that dimensions of the plan-form geometry were obtauied from field investigations. However, instead of duplicating the measured channel, a comparison was made to the appropriate Rosgen Spe channel. An hyd~~ulic dysis was then performed, using bankfull, riparian and floodplain flows, to confirm that the prelmmorphological dimensions met the requirements of flow containment and erosional stabhty. Subsequentiy, the design was then evaluated as to its compatibdrty with other environmental design objectives. The main premise for this design process was that there were sufncient channel specifications avadable for Rosgen type channels.

Shortly after the release of the MT0 Drainage Manual (1992), a complete revision was underraken. The channe1 design chapter of this revised Manual focused more on fluvial geomorphology than on classical open channel hydraulics. Channel design methods were similar to those presented in the earlier version. Addaional information on stream geomorphology was included in the Manual as a chapter of reference material. It provided more background information on relationships amongst dey,channel and bdorm segments, which was necessary for a charme1 design that would emulate nanual hctions and therefore would be 'PeE-

The revised Manuai (MT0 1997) provided details on ten steps to assess the stabdity of a strearn including consideration of fish habitat as follows:

Assess geomorphic setting

Evaluate environmental conditions

Evaluate along stream reach

Assess the characteristics of the stable channel

Assesç degradaüon process

Assess process

Assess lateral shifüng

Assess rates of stream channel change

Hydralogic pararneter

Sediment transport

Resistance to flow

Re-iterate degradation/aggradation assessment

Conclusions for planners and designers

UnfortunateIy, it is unclear as to how the chapter on channel geomorphology shouid relate to the previous chapter on design methodology of stream channels. One possibly usefid relationship between maximum pennissible velocity or maximum permissïble tractive force and chamel stabdity was not established.

Newbury and Gaboury (1993) presented a "10 step" Stream adysis and design procedure after sevdyears of observations and study of watersheds and rivers in Manitoba Fish habitat and habitat rehabilitation was the focal point of this manual whereas water conveyance was the prMary concern of the MT0 Drainage manual. The range of spatical scales fkom catchment to hyporheic zone were catagorized into five levels of nested habitat (valley, reach bedform, boundq layer and substrate flow). This was sirnilar to the general systems approach proposed by

Orsbom and Anderson (1986). The procedure recommended by Newbq and Gabow (1993) is

Iisted below:

PLANNING

1. ldentify delineation

2. Prepare longitudinal channel profiles

3. Prepare flow summary

FIELD EXPLORATION

4. Survey channel geometry of nearby reaches

5. Survey reach for rehabilitation

EVALUATIONOF STREAM BEHAVIOUR& CHARACTERISTICS

6. Detemine hydraulic characteristics and habitat conditions of each of the reaches

Channel hydraulics, stability, geometry and pattern

Flow frequency (annual series. bankfull)

Flow conditions and hydraulic

DESIGN& CONSTRUCTION OF STREAMHABITATS

7. Select and sue rehabilaationworks

8. Test design for instream flow requirements

9. Supervise construction

10. Monitor and adjust design

While the emphasis on fish habitat was a valuable addition over other design guideluies, quantitative engineering and geornorphology design criteria were dinicut to ascertain. The focus appean to be on longmiduid profile and Meconstruction. There is very little discussion and/or details on plan geometry and pool construction. The installation of structures was recomended for rnany channel design or rehabilitabon projects. meswere considered a structure and were constmcted on the channel bed as opposed to grading the channel bed to create the riffle.

The similarîty amongst these three design guidelines was the inclusion in al1 three of the use of observe& presumably natural, river pattern during the channel design process. ïhere was also recognition of the presence of bedfoms in the channel and the need to consider their characteristics in the channel design. What was missing was a clear definition of bedfoxms, such as nffles and pools, and statements describing the conditions under which they exist.

2.1.2 Recent Channel Construction/Restoration Efforts Several projects that required the "design of a naturai channel" by the proponent have recently been consûucted in Southem Ontario. Projects in which detailed idonnation on the designed chamel ntas readily avadable included Henry Stum Creek, Colonial Creek, Kolb Drain and Groff Mill Creek. Idormation on these designs was made available by the local Conservation

Authori~tvhich granted "Permits to Alter an Existing Watenvay" under the Conservation

Authorities Act.

These four reaches were all within urban areas' were fairly short (100m - 800m) and narrow (lm - 3m) and were tow-gradient, meandering charnels. A variety of techniques were used to determine the final design of the channel. The most common procedure was to attempt to determine the most stable channel form using Rosgens classification systern, compare the existing channel Nith this "preferred" condition and hally ensure that the 'hreferred channel geometry had the capacïty to pass specified storm flows. However Mejustification was &en to support the horizontal and vertical dimensions, if and whm they were included, of the proposed chamel. It

was unclear as to which of the recent Ontario design methodologies was foilowed but it appeared

that some form of the MNR Natural Channel Systems Approach was used. Most commonly, the

horizontal alignment was provided with approximate locations of rimes and pools. Occasiody,

chainage accompanied this alignment. Vertical alignment was provided for one project in the form

of a longrtudinal profile and in another project spot elevations were superirnposed on the horizontal

alignment. Riffie and pool dimensions were presented as "typical" cross-sections. Variables used

in the Rosgen classification system were the main design parameters used in these designs.

Derived values of channel geometry were not confliimed with available empirical or theoretical

relationships.

2.2 Rber Channels and CZasszjication Systems KeUerhals et al. (1976) stated that "consistent river channel classification, with emphasis

on those aspects of river behaviour that are most important in practical problems,

is a prerequisite to the study of river processes". It is implied that misinterpretation of river processes, if it leads to an engineered solution mismatched with these processes, may have disastrous consequences. It has been recently recognized that although straight, trapezoidal concrete channels may satise flow conveyance criteria they rnay cause cumulative, detrimental

impacts on the local and dowIlStream river systern (MNR 1994). This means that identification of the ''most important aspects of river behaviour" must proceed beyond specification of design flowrates. Unfortunately more than 20 years have passed since this staternent was made and it remains unclear as to how to interpret observed river patterns in a particular geographic region

such that engineering works in the river in question will be successful.

Reviews of several classification systems are presented by KeUerhals et al. (1976), Koighton (1984), Molinas (1994), Rosgen (1995) and Anaable (1995) and are SUITLZflilfiZed in

Table 2. River classifkation systems may be categorized into bvo general types; one that is based

Table 2. Surnrnary ofriver c~assificafionsystermILS

Reference Description Unit Davis (1 899) Old, mature, youthtiil; based on slope and sinuosity Plan Horton (1 945) Stream order Plan Wolman and Leopold Sîraight, meande~g,braided Plan (1957) 1 Schumm (1 963) Sedunent type & transport mode, channel stability (excess, 1 Variables deficit or sufficient amount of sediment) Thombury (1 969) Vailey morpholog (consequent, subsequent, anticedent, Plan supercedent) Dury (1969) General inventory of channel plan fonn directly fiom Plan observation I Meandering, braided, straight, straight-simulating, deltaic distributory, anabranching, reticuiate, irregular Khan (1971) Sand-bed channels, , slope, sinuosity Mollard (1973) Continuum of river charme1 types, air photography analysis Plan uses total sediment Ioad, channel gradient, channel sinuosity and channel stabiiïty Brice (1 974) Degree and character of sinuosity, braiding, anabranchng Plan Kellerhals et al. (1 976) Method to summarize field data fiom 108 Alberta nvers Plan+Data Channel pattern, islands, channel bars Mosley (1 9 84) reach setting, scenic quality, geomorphology, vegetation, channel pattern, channel boundary conditions & materials, water quality Rosgen (1 995) Geomorphic and morphologicai characterization, stream Variables condition and field data vd~cation on plan-form evaluation, typically through the use of aerial photographs, and the other on a hinction of the independent variables, some of which may be measured in the field, which determine channel morphology. The large number and variety of proposed classification systems indicate the cornplexity of the relationships arnongst river channe1 variables and of user ne&.

Emphasis may be on the river-vailey relationship, sedimentology, air-photograph analysis, longitudinal cornparison of reaches, or changes in a particular section fiom year to y=, One thing is particularly clear, there exists an extrernely wide range of channe1 types as well as a wide range of types within a single river systern. The latter range shows that there is an ordered progression of channel morphology from the headwaters to the with a large lentic water body as suggested by Schumm (1977). Despite the variety of classification systems they share recognition of cornmon patterns of suggesting an underlying channe1 structure giWlg rise to these patterns. This structure would include bedforrns and bedform sequences.

The Rosgen classification system appears to be one of the few c1assification systems that deals directly with the bedform sequence. Others refer to individual bedforms such as bars, ripples or but seem to either neglect or only indirectly make reference to the observation of a repeating bedform sequence. Even though objective details on the bedform sequence are lackmg,

KellerhaIs et al. (1976) note that the characteristics of channel bars and major bedfoms contain more information on charme1 processes, and sediment transport in particular, than aq other river feature.

Due to its inclusion of channel forrn and described relationships to channel design,

Rosgen's classikation system has received considerable attention in Southern Ontario fiom engineers, geomorphologists and biologists. It may be considered to be a combination of classical plan form evaluation and specific field measwements. It classifies a homogeneous, stable reach using geomorphological and sedimentological characteristics. Measurements of bankfull width, bankfulI depth, sinuosity, Stream gradient, flood-prone width and mean bed-particle size enable the stratification of reaches into discrete classes. These classes have been established in such a manner that if one of these parameters is significantly altered, naturally or anthropogenicdly, one or more of the remaining parameters would adjust, shifting the resulting channel into a Merent class . The two cornmon presentation formats of the Rosgen ~Iassificationsystem are a form of a dichotomous key and a listing of the magnitude of the variables within each class. These criteria have been re- organized into the format illustrated in Table 3 that ai& in comparing the criteria arnongst the classes. Table 3. Rosgens c[ass1j7cationsystern highlighting stream types (C. E, fl with me-pool sequences.

Rosgen's classification system is one of the few that considers the three-dimensionai structure of the chanael; plan (sinuosity), profle (siope) and cross-section (width:depth ratio, entrenchment). It also attempts to quant@ the relationship between the Stream channe1 and its valiey. Finallyy it is the only one that emphasizes the longitudinal repetibon of bedform-feature pairs. However, Rosgen (1995) irnplied that the riffle-pool sequence occurs in al1 sediment types

(bedrock, bouider, cobble, gravel, sand and silt/clay) which conflicts with Leopold (1994) who stated that "pools and rimes do not occur in channels whose bed consists of sand". Leopold, et al.

(1964) correlated the bedform feature to the dominant substrate size, npples and dunes in sand channels and rifnes and pools in gravel charnels. Ashmore (P. Ashmore, Professor, Deptartment of Geography, Univers* of Western Ontario, London, Ontario, 1998, personal commuaication) stated that "pool-rif£le features are bedforms of mobile bed chamels" and could not occur in bedrock. The one additional feanire that Rosgen (1995) mentioned in his classification of "C-type" channels was the presence of a characteristic point typicaliy lo~tedon the inside of channel bends. This 'bar-fom" is include here in the three-dimensional shape of the pools. Rosgen (1996) compiled detailed descriptions for d these stream types into a text.

Several features of each of the stream types are characterized including valley type, gradient, bank and bed rnaterials, associated geological features such as alluvial fkm or valleys, giaciolacustrine or glaciofluvial deposirs, moraines, tills and coane textured colluvia1 deposits, channel stability, type of sediment transporteci and bedform features. However, descriptions of bedform features for stream Spes F 1, F2, F6 and E3 were lacking and only pools were briefly mentioned for C 1 and C2 meam types. The only mention of the bedforms commoniy found in sand channels, ripples, and , were for the CS stream type where they were noted as being prevalent following a description of rime-pool sequence of t5s Stream type.

Clearly, the tenninology for bedfiorms needs to be more carefiilly defineci and consistently applied in the Rosgen ~Iassificationsystem. It appears that this classification systern may define bedforms fiom observations of fluvial conditions rather than fiom topographe or sedimentologic criteria. Church (1992) provided a usefùl surnmary of bedforms and the channels in which they are found suggesting there is a relationship between bedform type and small, intermediate and large channels. Amable (1995) compounded this problem by providing only rime-pool dimensions in al1 the case studies. For example, Rosgen indicated that "rapids" with infrequently spaced scour pools characterize B-~pestreams. This terminology uias not used in Annables (1995) case studies although they were the features that were observeci and surveyed in the field.

Rosgen (1996) emphasized the significance of bedfoms by stating that rimes, depicted graphically but not described in any detailed way in the text, are the preferred location for collecting morphological data in rif?le-pool and sep-pool systerns. The importance of bedforrns was Merstressed by stating that these two features tvere the locations where banI6ull stage was measured and that baddfull stage was ;'the single most important parameter" used in the Rosgen classification system. Rosgen recomended collecting channel-material data at specific locations in the bedform sequence so that various bed features are sarnpled in proportion to their presence in the reach, based on linear distance. This method did recognize the relationship bmeen particle size and bedfiorm feature.

The ody physical dimensions of bedforms, presented by Rosgen (1996), aside fiom the dimensions imbedded in the classification were:

the inter-bedfom distance, rneasured along the , was proportional ta the bankfull wïdth (the water surface width aççociated with the discharge that charactertzes the morphologic pattern and sediment transport of a strearn (Annable (1995)) and.

the water surface dope may be esümated by the channel dope between hopoints at the upstream end of successive fifiies. The Rosgen classification suggests that bediForrn features are a function of channel morphology and independent of bed and ban.substrate.

AnnabIe (1995) conducted a study to determine if there existed a correlation between selected hydraulic and morphologicai relationships of the Rosgen ~Iassification for rivers of

Southern Ontario. A total of 47 reaches were surveyed in 1994 of which 20 were gravel-bed (5 bedrock, 2 boulder, 11 cobble, 8 sand, 1 sÏlt/clay) and 26 were C-me (2 A-type, 7 B-type, 8 E- me, 4 F-type). The mo most common types of graveLbed rivers studied by Annable (1995) were

C-type (C4, 11) and E-type (E4, 6). Data dysis compnsed calculating power-hction relationships between measured variables (iisted in Table 4) and ratios of selected measured variables. Two examples of these ratios are balwidth:badcMl depth (widthdepth ratio) and flood-prone width:bankfirll width (entrenctunent). The anaiysis centred around the assumptions that Rosgm classification system was applicable to the rivers and streams in Southern Ontario and that the relationship presented by Lane (1959, Table 4. List of variables measured by Annab le (1 995).

Longitudinal- 1 Plan 1 Cross Section 1 Sediment (d16,d2sdso,d~s,dd Stream gradient SinuosiQ Bankfull depth Pebble count Vaiiey gradient Belt width Bankfull width Pavement Rifne length/gradient Meander wavelength Flood-prone width Sub-pavement Pool lengtldgradient Meander amplitude Wetted gexineter Bar Radius of curvature Bankfull arealdischarge 1 1 Bar length/pdient 1 Measuremmts in bold are used for the Rosgen classificationsystern

sta-ting there exists a balance between water and sedunent transport through a reach, applies-

Specifically Lane (1955) proposai the following:

Correct determination of bankfull depth, which 41be discussed in a later section, was extremely

significant for this analysis. Many other ratios tvere dependent on this parameter. Provided that

bankfidl depth rnay be determined with a reasonably high level of certainty and that bedform

features are cleady defined, then the Rosgen classification system and the analysis of Amable

( 1995) rnay be extremely usefUl tools for designing river charnels.

2.3 Large Scale Characteristics of Rivers

2.3.1 Physiography and River Valleys Bedrock and the overlaying unconsolidated materials (predorninantly glacial drift in

Southern Ontario) provide the primary physicai structure of a watershed and its watercourses. The

orientation of the bedrock surtàce often controls the overall slope of the overlying materials and

where it is close to or exposed at the ground surface, it controls the siope of the . The volume and temporal pattern of streamflow, channel gradients and the type of drift detede the

size of the valleys, affect the rate of sediment transport and ultimately the morphology of the river channel (Chapman and Putnam 1984). The drift features presently found in the rivers and streams

in Southeni Ontario were created during the last glaciation and are described in great detail by

Mollard and Janes (1984).

The interaction between the flowing water and the drift results in particle entrainment,

transport and deposition. A significant change to one of the variables in Lanes' (1955)

proportionality was considered a perturbation to the river system which in turn wouid respond in

such a mamer that a stable condition was re-estabfished- The valley in which the river was

flowing provided constraints to the magnitude of this adjustment. Therefore local disturbances

may have regional consequences. Mollard and Janes (1984) +mmmrked this vailey-channel

relationship and its perspective on channel design:

Understanding the eroszonal and depositional processes. recognizing the and sedzments that they produce, and interpreting the conditions that caused them, yield a spectrrcm of usefil information that can be applied to a wide variety of engiheering, geo logical and environmental problems.

A widely used descriptive mode1 of the drainage system is that of Schumrn (1977)- The system was divided into three parts, the uppe. middie and lower. The upper (production or headwater) zone is where most of the water and sediment for the river originates. The midde

(tramfer) zone is the alluvial reach where the river channe1 is most stable and where its configuration is the best defined. The lower (deposition) zone comprises the delta where the river deposits most of its load.

Galay (1987) suggested a modification to Schumms' (1977) concept by expandirg the rniddle (tramfer) section into a deposition reach and a transport reach as well as expanding the lower section into a desposition reach and a deltaic reach. Deltaic reaches occur when a river enters a large such as a lake or ocean. The fluvial conditions in this region pose several cornplex issues for engineering works in contrast to the other three (erosion, transport and deposition) reaches. In this context, considering sinuosity and channel slope, riffles and pools should occur in the transfer reaches of the watercourse (Rosgen 1995).

Rivers thus perforrn significant amounts of work shaping and reworking the drift features.

The fundamental concept necessary to understand when studying river channels is that strearns develop within deposits of the material being transport by the strw that i$ streams are seE- formed (Galay 1995).

In commenting on the applicability of Rosgens classification to geologic conditions in

Ontario, Ashmore (P. Ashmore, Professor, Deptartment of Geography, Univers* of Western

Ontario, London, Ontario, 1998, personal communication) raised several significant issues. Firc that rivers in Ontario have been subjected to a relatively short post-giacial penod and that the present watercourses are considerably dler in size than the watercourses that originally deposited this "~uviurn7'.Second, these streams may only be partiy competent to move this glacial material. This has significant implications on designing channels in an area with a recent geological history like that found in Southem Ontario. The forces required to form river features rnay be larger than those that commody occur in Ontario under the present clirnatic conditions.

2.3.2 Meandering of river channels

The repetitive pattern of the plan form of a river. known as the meander, has been a cornmon feature of discussion amongst seved researchers studying difEerent aspects of a river.

These discussions have included river classification (Brice 1975, Kellerhals et al. 2 976, Mollard and Jattes l984), stable plan-form geometry and rates of laterai erosion (Langbein and Leopold

1966; Ferguson 1977; Chang 1984a), depositional feature development (Zimmeman and Kennedy

1978; Dietrich and Smith 1983) and secondary currents and energy losses through a curved section of channel (Chang 1983; Johannesson and Parker 1989; Jin et al. 1990).

Many river classification schemes, some of which have already been discussed, are

developed based on the observed plan vîew of a river (Brice 1975, Keiierhds et a[. 1976, MoUard

and Janes 1984). These types of classification systerns, as cornpared to those that consider

hctions of independent variables that determine channel morphology, ~picalIyconsider the

channel to be stiraight, meandering, braided or some variation therein. The classifications described

by Brice (1975) and Mollard and hes (1984) were derived fiom extensive review of aed

photographs. Interpretations were made regarding the channel type (coh~uaconfined or

entrenched meanders? serpentine or sinuous meanders), typical environment (floodpIain and valley)

and typical bed and bank materials.

Kellerhals et al. (1976) extended this type of nver classification by including major

bedforms such as islands and bars with the channel pattern descriptions. Galay (1995) related the

categories of Mollard and Janes (1984) to the geological concept of a river with longitudinal

progression fiom headwaters to delta presented by Schumrn (1977). These systems provide a means of communicating the nature of a particular river reach to others and thereby are descriptive not functional. They are very subjective and require advanced interpretation to be used in a channel design context. A firnctional classification system, such as the one developed by Rosgen

(1999, rnay be more usefùl in a channel design context.

The meandering pattern of a nver has been suggested as being the most stable fonn of the channel and that rates of lateral erosion are directly related to the meander (Langbein and Leopold

1966; Ferguson 1977; Chang 1984a). It has also been associated with depositional development (Zimmerman and Kemedy 1978; Dietrich and Smrth 1983) and with secondary currents and energy losses through a curved section of the channel (Chang 1983; Johannesson and Parker 1989; Jin et al. 1990)

It has been observed over many years that rivers exhibit a sinuous pattern in plan and profile as they proceed fiom the headwaters to a Iarger water body. Keller and Melhom (1978) demonstrated, quantitatively with data fiom 251 pools in eleven streams, that there was no significant merence between the mean spacing of pools in bedrock and alluvial Stream channels.

The pool spacing was normally distributed and closely correlated with channel wicfth. The sinuous profile of a channel demonstrates the topographie highs (fies and steps) and fows (pools). In plan, the meander comprises a repeating sequence of "left pool - rifTie - right pool - riffle - left pool" commonly refereed to as one meander wavelength.

2.3.3 Dominant Discharge Having discussed the Iarger scales of the vdey and floodplain one must then consider the scale at which fluid forces are acting against geological resistance. Bray (199 1) considered gravel- bed channels as 'threshold" channels since the rnaterial within the becomes actively mobile oaly when the discharge exceeds some threshoId value. This value is closely related to what is cornrnonly known as bankfull stage, defined by Dunne and Leopold (1978) as the

"discharge at which moving sediment, forming or removing bars, fomùng or changing bends and meanders, and generally doing work that results in the average morphologie characteristics of channels". This definition is consistent Rith Lane's (1955) concept of a balance between water and sedirnent transport.

Knighton (1984) suggested that bankfull flow may be defined as either the flow which detennines particdar channei parameters or the flow which performs the most work (curnulatively transports most sedirnent). The degree of similanty between these two discharges is not clearly defined and difficdt to vew. Collection of discharge and sediment transport data at or above bankfiill flow is extrernely difficult. As weU, there are considerable discrepancies among the

methods of deterrnining, in the field, the water mdâce elevation corresponding to this discharge.

However, it can be generally agreed that there is a reIationship between flows greater than some threshold, sedirnent transport and observed bedform features and that there are complex taoporal and spatial feedback mechanisms arnongst them.

The ody method of determining badd5.U conditions that includes flow and sedirnent data is that of Wolman and Miller (1960). it requires a series of sirnultaneous rneasurements of discharge and sedunent transport rate. The product of the frequency of the discharge and the correspondhg sediment transport rate is plotted as a fbnction of discharge. The innection point of this curve, a local rnaxkuq defines the bankfiill discharge. A stage-discharge cuve may then be referenced to determine the bankfull elevation. As might be expected fiom the description of the method, it requires considerable time and effort and therefore has Iimited pradcal application.

Williams (1978) briefly summarized various previously used methods of detemiuling bankfull discharge fiom field observations or calcdations. They codd be categorized into those that required recognition of sedimentary surfaces (valley flat, benches, channel bars), those that required observations of bounclary features (vegetation, debris, scars) and those that required measurernents of cross-section profiles. He then proceeded to define and discuss five general methods of determining bankfull discharge; stage-discharge cwe, hydraulic geometry relationships, cross-section geometry? flow-fiequency curve and Mannings equation. AlI but the cross-section geome&y method involves some fonn of field observation. Unfortunatdy* Williams

(1978) does not sufficiently describe the available field methods for determining banl$U11eIevation.

Johnson and Heil(1996) reiterate the difEiculty of detennining baukfd elevation but stress that it is the basic input parameter to channel classification and design. They suggest representing bankfùll elevation as a fiizzy number thereby quant@ing the variable nature of bankfull elevation-

Leopold (1994), perhaps realizing this apparent ambiguity, discussed bankfùll elevation width,

depth and discharge in great detail. He suggests flagging severai points dong a reach that are

estimated to be the location of bankfllll elevation. Subsequently, these points are surveyed dong

with the adjacent channel bed elevation. The ba&X depth is the vertical distance between the

parallel best-fit lines drawn through the two data sets. This method accounts for local variability in bankfull elevation previously described. The criteria Leopold (1994) uses for detennining bankfùll stage in the field, in order of usefüiness, are top of the point bar, location of change in vegetation, local topographie break and change in size distribution of materid at the surfàce

This particular discharge is extremely signifiant for channel design; it has meaning for sediment transport and also yields dues for proper channel dimensions. It is thought to control horizontal and "vertical" meandering, namely the channel sinuos* and the riffle-pool sequence. It also provides a valuable reference point in the flow data for channe1 design and bas been recognized as such in the MNR Guidance document (MNR 1994).

2.4.1 Bedforms in gravel-bed rivers - Ritlies and Pools "Natural channels rarely have flat beds. Shear stresses above the critical for transport rnould COhesionless b eds into discemible fonns whose geornetry depends on various Jlow parameters which in tum are influenced by those forms, giving rise to compfex feedback relations" Knighton (1983)

A number of researchers (Leopold et al. 1964, Dolling 1968, Tinkler 1970) noticed a relationship between a sequence of afternating shaitow and deep water regions and the plan form meandering of the channel. Leopold et ai. (2964) adopted temiinology commonly used by angiers, ritnes and pools, to describe the bedform features they observed in meandering charnels (Figure 2-

1). Interestingly enough, Leopold, et al. (1 964) used these terms to descnbe the characteristics of the water surface and yet the terms have evolved to include the riverbed. Rifnes and pools rnay be fiirther discretized at increasrngIy smaller scales depending on the need of the study (Church 1992).

A detailed cornparison between step-pool, rifne-pool and cascade-pool systems is provided by

Hogan and Ward (1997).

Mer Yang (197 la) demonstrated that the '4aw of least time rate of energy expenditure" govemed the formation and behaviour of meandering streams he went on to dernonstrate that the formation of rifnes and pools were a integral component of this energy-expenditure hypothesis

(Yang 1971b). This work recognized that the slope of the energy grade luie dong a reach at low flow was not uniforrn but varied in accordance with the nffle-pool sequence. Stali and Yang

(1972) stated that the hierarchy of mechanisms through which a Stream system can adjust itself to minimize the unit stream power was first to create nffles and pools, then to create meanders and hally to adjust its longmidioal bed profile over a larger scale.

I

Figure 1. Schematic diagram ofriJle-pool sequence. Severai objective criteria have been developed to Merentate riffles and pools based on flow parameters or substrate characteristics (Table 5). Table 5. Summary of the variables used tu define rifles and pools. Method Rifne Pool Reference Bed matenal size coarse materid fine material Leopold et aL (1964) Linear regression of bed Idtopogqhic hi& local topographic Low Richards (1976), Milne (1982) topopphic data Becifom differencing of bed Ldtopographic high local topographic low O'Neill and Abrahams (1984) topographic data Residual depth na bachater depth hm Lisle (1 987) downstream fiecrest Froude number supercritical subcriticai Wob(1955) En- grade line (approx Sa' Sa S, < SO Yang (1971) by water surface dope) VeIoc@cdepth ratio >3.20 CI.24 Jowett (1993) Froude nurnber >0.41 <0.18

Differerrtiating rimes and pools using fluvial characteristics requires previous knowIedge of the locations of these bedfonns as might be determineci fiom a topographic survey. A majority of the fluvial criteria have a temporal component, in particular a dependency on flow stage (Richards

1976a), wfüch has made it difficult to apply them to all situations. Richards (1976a), after perfonming a spatial series analysis on rime-pool sequence? concluded that the nffle-pool sequence was far more sigdicant on flow geornetry than plan fom geornetry.

It should be apparent at this thethat rifnes and pools are a significant morphological unit of many streams. Many of the physical and fluvial characteristics Listed in Table 2-4 warrant

Merdiscussion since they rnay be valuable channel design criteria. Distinctions of these characteristics may be made either witbin or between features (length of a nnie and the distance between successive tops of rifles).

2.4.2 Physical Characteristics of Rimes and Pools

2.4.2.1 Longitudinal Dirnehns One of the most fiequentlyquoted relationships in fluvial geomorphology is the empirical obsenation of Leopold, et al. (1964) that the distance between two successive pools, measured paraiiel with the valley axis, is approxhately 5 - 7 channel widths. Keller and Melhorn (1978) measured the spacing of 25 1 pools in 11 channels (7 in and 4 in bedrock, channel slop 0.1% to 0.8 %, sinuos@ 1.O 1 to 2 -40) and concluded that there is no sigmfïcant ciifference between the mean spacing of pools in bedrock and alluvial stream channels. The calculated relationship was y = 5.42 x'"' (where y = pool-pool spacing (m) and x = channe1 width (m)). There was Me discussion on the region between the pools except that they were rimes in alluvial streams and benches in bedrock streams md both had similar water &ce profles at low flow. While these dimensions are scalable to a channel dimension such a width: other dimensions of riEles and pools, such as bed slope, are independent. Newbury and Gabory (1993) suggested that the channel dope of the upstream side of a nfae should be 4h:lv (25%) and that the channel dope on the downstream side of the nfae should be 20h: lv (5%). There was no mention of any longitudinal dimension of pools-

Annable (1995) determined that the slope of rïf£ies and the slope between pools were &vice and half that of the overd local stream gradient respectively. These observations correlateci with the findings of Yang (197 1b) assuming that the energy grade line slope approxirnates the bed slope.

Auother common tem used to describe the large-scale dimension of a reach is sinuosity which rnay be easily calculated fiom topographic maps. However, care must be taken because only the valley slope may be directly measured fiom these maps. No information is given about the nature of the channel bed elevation. A thorough understandhg of the relationship among valley, reach, riffle and pool bed slopes is necessary for the successfül design of a river channel.

2.4.2.2 Cross Sectional Feaîures The most distinguisbg feature of the rifne-pool sequence is the repetitive longitudinal and lateral pattern of alternathg cross-section symmetry. In the longitudinal direction, the channel cross-section alternates between spmetric (nffle) and asymmetric (pool) while in the iateral direction the shape of the asymmetric cross-section altemates between being skewed to the lefi and being skewed to the right-

Leopold and Maddock (1953) originally proposed the use of power or linear log-log

fiinctions to descnie the relationships between discharge (the dominant independent variable) and

several dependent variables such as width, depth and velocity. These fimctions are comrnonly

described accordingly:

Since Q = W D V, the surn of the three exponents, b, f and m should be 1.0. It foilows that

analyzing the relative magnitude of one value to the other two may be usefui in interpreting the

fluvial properties of rivers. The work of KeIIer (1971), Stall and Yang (1972) and Richards

(1976) found a Merence in these exponents between &les and pools (Table 6).

Table 6. Two cases demonstrating the dfirences anzongst the b-f-m exponents between riffles and pools.

Richard (1 976) Stall and Yang (1972) Exponent Pool Rime Pool Riffle b 0.036 O. 16 O. 17 0.3 1 f 0.33 0.34 0.26 0.33 m 0.64 0.49 0.57 0.36

Keller and Florsheim (197 1) proposed the "veIoci@-reversal hypothesis" to explain the observation that îhe veiocity exponent was higher in the nffles at low flow (rnae>rnpoal)and "reverser such that the velocity exponent was higher in the pools (ma,

m (velocity, depth) -=1 f Sediment transport

iI Mannings equation -=-m 2 f3 m=b+/orm=05 (velocity, ara) Channel stability

The coefficients calcuiated by Stall and Yang (1972) and Richards (1976) for pools and mes plotted in two Merent zones, suggesting that the most sigdcant merence between the two features be related to the ciifFerence in velocity-area ratios (Rhodes 1977).

2.4.2.3 Bed Roughness Bed roughness may be described by a rnetric of the distribution of sediment particles within the fiquently wetted perimeter of a channel. Cornmonly used methods to determine the grain-size distribution are bulk, grid, areal and transect sarnpling (Yuzyk, 1986). The horizontal spatial distribution of particles is extremely variable in gravel-bd channels (Kellherhals and Bray.

1971; Hey and Thorne, 1983). Vertically, gravel-beds tend to bave a unimodal surface layer overlaying bimodal subsurface material (Bray and Church, 1980; Parker and Sutherland, 1990).

The mean particle diameter of the surface layers tends to be larger than that of the subsurface layer. This vertical variation is commonly delineated into pavement and subpavernent layers although there are sorne discrepancies between the use of the terrns pavement and arrnour to descnïe the surface layer @ray and Church, 198 1; Parker and Sutherland, 1990). This discussion, however, is more applicable to sediment transport issues and dlnot be considered merhere. Most important is the longitudinal particle-size variation its relationship to the riffle- pool sequence and the sediment-water intefice.

It is generally accepted that particle sizes Xe larger in the rifnes than in the pools (Keiler

1971; Lisle 1979; Knighton 1984 Milne 1982, Clifford 1993a). The mechanisms creating this observation are, however, not cleady understood. The velocïly-reversal hypothesis (Keller 1971) suggests that local sediment sorting mechanisms scour ses and fill pools during low flow and fill fies and scour pools during higher flows. Another theory, dubbed the ''kinematic wave theory"

(Langbein 2 968), suggested that when a dcient number of sediment particies are in motion a kinematic wave develops Rrith aiternating regions of high and low particle concentrations with individud particles moving slowly and quickly, respectively, through these regions. The regions of hi& and low particle concentrations coincided with the riffle and pool features of gravel-bed rivers.

Recent work by Clil3ord (1990), who measured the three-dimensional velocity distributions in riffles and pools, supported the latter theory.

Bed roughness may be described directly (particle size) or indirectly (flow resistance coefficient). Standard techniques of the former sort a sample of particles according to nurnber or weight and sumnlarize the rdts according a standard scale such as the Wentworth scale. The size distribution of the particles is often lognormal (Kellerhds and Bray 1971). Two metncs commonly used to describe the cumulative fkequency distribution are the median particle size, dso, and the standard deviation ((dSddlo+ ds4/dso)/2) (Gilbert, 1987). Grave1 is defined as matenal with a particle size between 2 and 64 mm (Yuzyk, 1986) which is the same range used by Rosgen

(1995) to describe gravel-bed strearns.

hdirectly, bed roughness is reflected in the seIection of a flow resistance coefficient in equations comrnonly used to estirnate average velocity at a cross-section (Bray 199 1). Three of these equations will discussed in the following section on 80w resistance. Given that these coefficients are firnctions of particle size and that particle size varies between =es and pools, it follows that two dBerent coefficients may apply to a single gravel-bed channel.

2.4.3 Fluvial Characteristics of Rimes and PooIs

It is well known that the fluid velocity in a channel section varies fiom one point to another. This phenornenon resuits fiom bed and bank shear stresses as well as the presence of a free surfàce. The instarrtaneous velocity has components in all three planes of a Cartesian co- ordinate system and, in order of dominance, is in the longitudinal, vertical and Iateral directions. A considerable amount of work has been conducted over the years studying the spatial and temporal vanabil* of fluid velocïiy in rivers. Spatial vanabiw includes variation within and between vertical velocity profles and the presence of secondary currents and bou11dat-y shear stresses.

Velocity may change in the order of hundredhs of a second (turbulence) or in the order of minutes, hours or days (directiy proportional to discharge). Riffles and pools kctor prominently in this variability due to their three-dimensional shape and differential sedirnentology.

2.4.3.1 FIow resistance Extensive discussions of flow resistance in an open-channel are provided in most open- channel hydraulic texts, Le. Henderson (1966) who states "A resistance equation can be derived by bdancing the retarding shear force at the boundary against a propulsive force, the weight of the flowing water resolved down a slope, acting in the direction of flow", Two significant factors that must be considered in flow resistance equations are the existence of a free sdceand the highly variable shape of the cross-section or bouudary. These factors make the boundary shear distribution non-uniform. Detennination of this shear stress is Mercomplicated by the presence of secondary currents in both symmetrical and asymmetrical cross-sections. Equating gravitational and shear forces yields the mean shear stress: Since the local velocity gradient is proportional to the local shear stress, the velocity distribution in a river cross-section is also highly variable. Three commody used equations to

cdculate average cross-sectional velocÏty (Bray, 1991) are the Man.(Equation 2.4): the Darcy

Weisbach (Equation 2.5) and the Keulegan (Equation 2.6):

Calculation of the average velocÏty requires knowledge of the boundary roughness (n. f; k,), the cross-sectional geometry (R) and the dope of the energy grade line (S.). Manning's eqdon is comonly used in open-charnel hydraulics calculations although the Darcy-Weisbach equation is recomrnended for its dimensional correctness and stronger theoretical basis (ASCE 1963). The

Darcy-Weisbach fiction fador is commonly used in head loss (4)calculations:

The Keulegan equation has an advantage in that the coefficients, u* and k, may be detennined diredy fiom measured velocity pronles within the cross-section. An equation describing the velocity profile of turbulent shear flow for a hydraulically rough surface (Equation 2.8) may be derived fÏorn Prandds mixing leogth eqyation ( du / 9 = (1 / ~~rl~-)(l/y)) (Chang 198 8b). The boundary condition was taken at y = k, where the velocity was assumed to by ul. The constant of inteption, ul/u. , commonly represented as B, was experhentally determuied to be 8 -5 - The vonKarmen constant, K, has the value of 0.4 for any degree of roughness in a homogeneous fluid provided the roughness element is significantly srnall compared to the bomdary layer thickness

(Chang 1988b).

If the relationship between u and in@) in the Lower 20% - 30% of the profile is hear then the above equation may be represented as:

I b = Bu. --u. lnk, K

The intercept may be re--en in temof k,:

The roughness length (height above the bed where u = O), y., is calculated from the velocity profile

(Equation 2.10b) and is commonly assumed to scale with the roughness of the bed (Chow 1959'

Carling 1992). Bray (1980) and Hey (1988) evaluated the effective value of k, fiom different data sets fbr naturd gravel-bed river reaches and determineci that k, = 6.8 dS0. Carling (1992) suggested that k, ranged fiom 15 mm for a flat gravel bed to >300 mm for rocks. An estimate of the roughness length can be obtained assuming y, = d5d30 for sand (Chow 1959, Carling 1992) or d5&5 for well-sorted gravel (Carling 1992). The roughness length may range from 3.0 mm (fine gravel) to 16.4 mm

(coarse gravels) (Carling 1992). The local shear velocity ranges from 0.036 (flat gravel bed) to

0.046 (rocks) m/s and may vqacross the width of the river (Carling 1992). In other words, the local shear velocity across the bed may mer and wodd need to be intergrated to yield an average tenn.

Mannings n may be selected from tables listing values for a variety of channel types (MT0

1997) and conditions or calculateci using either a key (Chow 1959) or equations relating n to a characteristic size of wifiorm bed material (Bray 199 1, Newbury and Gaboury 1933). Most of these methods, except for that of Newbw and Gaboury (1993) are independent of water depth.

Newbun, and Garboury (1993) suggest three "cases" far Mannings n (Table 8) and in doing so attempt to account for the affect of ae-pool sequences on the average velocity.

Table 8. Three nzethods of calmlating Mannings n based on water deplh.

Case Criteria Method I depth > 3dSo 0.04(d~~)"~ II depth < 3dSo A caldate n frorn -R"'S~ '' 0 m depth shifts fkom (3 to >3 recognition of rimes and pools as discharge increases use eiîher 1 or II accordingiy

Rasgen (1996) irnplies that Mannings n is independent of stage but is a fundon of channel type and particle size; values for channel types C4, E4,and F4 are 0.0 19, 0 -032 and 0.03 2 respectively.

Dimensional analysis by Blench (1969) has show that the Darcy-Weisbach fiction factor is a function of the Reynolds number (4VR/V), the Froude number (V/(~D)'~)),cross-section shape and nirface texture and relative roughness of the bed m).Bray (1991) argued that the most sigdcant of these hctors is the relative roughness and suggested a log-linear relationship between the relative roughness and the fiction factor (Eqyation 2.1 1).

A thorough review of al. 61 and di are presented in Bray (1991). Those using dro as the characteristic particle size used values of al ranging fiom 1.98 to 2.36 and values of bI ranghg from 0.25 to 0.76 (Table 9).

Table 9. Range of coef$cients, a and 6,for Equation 2.1 1.

al bi Reference 2.00 0.35 Limerinos (1970)

2.36 0.25 Bray (1979) k - - -- 2.03 0.56 Hey (1979) 1.98 0.76 GrifEîhs (1981)

The coefficients used by GdEIhs (1981) were applicable for conditions where dS0 > II R S..

Values of the friction factor, f; range fiom 0 .O2to 0.90 for gravel-bed rivers (Bray 1972).

2.4.3.2 Energy Losses The total energy at a cross-section, Hi, is defïned as the surn of the water surface elevation

(Z+Y) and the vdocity head (a~2/2~)(Equation 2.12). The ciifference between the total head at adjacent cross-sections is dehed as the total head loss (Equation 2.13). Total head loss is cornmonly attnbuted to grain roughness but may also ïnclude loss due to expansion or contraction between cross-sections, loss due to fom roughness; loss due to turbulence

(Clinord 1990) or loss due to secondary currents in channel bends (Chang 1988a). The latter two occur at sdes much smaller than that which may be measured with readily available equipment.

Head loss due to grain roughness is calcuiated as the product of the energy grade line slope

(S,), derived fiom a £low resistance equation (Equation 2.4, 2.5 or 2.6), and the distance between the two sections 6).The mean energy dope between two sections is commonly calculateci using either the adbmetic mean (Equation 2.14a), geometric mean (Equation 2.14b) or hannonic meao

(Equation 2.14~)(HEC 1982).

The energy los between two cross-sections in which the cross-sectional areas are different is hown as expansion or contraction losses (HEC 1982). These losses are evaluated as the product of a coefficient, C, and the Merence between the velocity head (Equation 2.15).

[S.121

Expansion and contraction coefficients are ofien set to 0.1 and 0.3 respectiveiy but may be increased to 0.6 and 1.O in the vicinity of bridges (HEC 1982). Miller (1984) used the cross- sectionai area to distinguish which coefficient to use, either expansion (Adownrtrmm>qaPcraor contraction (&O-u'eam~Aupsaeam), and the hydraulic depth ratio to determine the magnitude of the coefficient. Values calculated by Miller (1984) ranged between 0 .O 1 and 6 -2 and the Merence is much larger than that reported by the Hydrologïc Engineering Center for use in their nater-nirface- profile program (HEC, 1982).

Form roughness, a term used by geomorphologkts to describe the energy lost due to bedform features, is not commonly used in open-channel hydraulics. Its closest equivalent is fitting losses used in pipe networks where the losses are the product of a coefficient, K, and the velocity head adjacent to the fitting (Equation 2.16). Another method suggests that the roughuess coefficient, either Manoings n or Darcy-Weisbach fiction factor, is the sum of a grain fiction and a form friction factor (Chow 1959, Gifiths 1987). The Mannings roughness coefficient is adjusted as a fimction of the degree of channel irregularity, the variations in channel cross-section and the degree of meandering (Chow 1959).

Heterogeneity of the velocw distribubon in a cross-section of a river often leads to underestimation of velocity head when the average velocity is used. This ciifference is resolved by ushg an energy coefficient, a,(Equation 2.17). There are two different techniques to caidate a (Huising, et ai. 1966). The arithmetic method

assumes that a cross-section is made up of a number of elements, each with a width and heighr, in

the centre of which a velocÏty value is known. The CCmethod-of-slices"requires that hes of equal

velocity, isovels, may be ciramm withùi the cross-section. The area between lines of successive

isovles is calcdated using graphical techniques or geostatistical software (Beebe, 1996). In a

sirnulateci rBle-pool sequence, Miller ( 1984) deterrnined that there was a significant difference

between the energy coefficient in the rifne and that in the pool. The former ranged fi-om 1.1 - 1.3

whde the latter ranged from 1-4 - 1-6.

Another way of expressing the total head at a cross-section involves the derivation of the

gradually-varied-flow equation fiom Equation 2.12. Several assumptions are made includïng the

slope of the channel is srnali and the channel is prismatic. A complete derivation may be found in

Chow (1959) and wiU not be included here. This form (Equation 2.18) of the equation is usefùl for

comparuig the nature of the bed, water and energy slopes.

2.4.4 Environmental Significance of Rimes and Pools: Fish Habitat The recent irnpetus to consider modifving classical open channe1 design procedures relates to the requirement to protect fish habitat. The federal Fisheries Act states ;'no person shall carry on any work or undertaking that results in the harmflll alteration, dismption or destruction of fish habitat" (Section 35(2)). It follows that a definition of fish habitat is necessary. As de& under the Fisheries Act, fish habitat is "spawning grounds and nursery, rea~g.food supply and migration areas on which fish depend directly or indirectly in order to cany out their He processes". It is generally agreed that there are six essential components of fish habitat (Milhous, et al. 1984, MNR 1984) (Table 10).

Table 10. Six essential components Offish habitat- ( Food ( Macroinvertebrates living on or in the substrate constitute as 1 1 1 sïgnificant portion of many fish species diet. Microscopie organisms 1 1 1 such as plankton and algae make up the diet of many small fish 1 1 Cover 1 instream or overhanging bank vegetation. ban.angleheight 1 Substrate Composition of siItlcIay, sand, grave1 cobble, boulders and bedrock, embeddedness Water chernistry Temperature, dissolved oxygen, pH, nitrate Water flow Annual base fiow, average annual peak flow velocity Channel geometq Width, depth, sinuotity, gradient, ri££ie:pool ratio, pool class absence of blockages preventing hhpassagehnigration

Rifnes and pools provide much of the above-noted components of fish habitat. Rifnes produce most of the food, fom spawning areas for reproduction and provide some cover for juvenile reariag. Since desare portions of the water column where water velocity is fast, depths are relatively shaiiow and the water &ce gradient is relatively steep, fish expend considerable energy to maintain their position in nffles (Platts et al. 1983). in contra pools provide areas of slower moving water where fish rnay easily maintain position, areas where the peak daytime water temperature is cooler than the average and areas with large volumes of overhead and laterd cover, especially where woody debris has accumulated.

Considerable effort has been made to quanw the relationship between streamflow and fish habitat. The variables that are of most importance in this relationship are water depth and velocity and stream substrate (Milhous et al. 1984). Cornputer models are used to predict these three variables which are collectively known as microhabitat. After conducting a thoro~ghreview of one of the most common models, Physical Habitat Simulation (PHABSIM), Shirveil (1986) summarized the limitations with the hydraulic simulations by rnakmg the following recommendations :

Transects must be placed at, and parallel, to al1 hydraulic controls within the reach this is often violateci since the conirol shift with a change in flow, surveys are incompIete or surveyed controls are biologidy, not hydraulically, signifiant The flow resistance coefficient must accurately reflect the spatially variable conditions wîthin the charme1 as weii as changes with strearnûow

Mannings equation is used where n is often constant but the '?me" value is not know~with certainty The spatial variability of veIocity must be well understood the mean velocity is erroneoudy extrapolated to distinct locations within the cross- section

sùnuiated velocities represent average vaiues withîn the water column whereas the critical location is close to the strearnbed (where fish spend a majority of their time) neextent to which simulated velocity and depth rnay be extendeci without significant change laterally and longitudinally must be known reaches are divided into rectangles with the longest axis oriented parallel to the flow, the width and length of this "cell" often is not a mitable reflection of the spatial variability wïthin the reach

Although there are many additional variables, such as those listed above, that are required to completely deke fish habitat, these three (velocity, depth, substrate) are recognized as being the most important (Beebe 1996, Lamoureux, et al. 1995, Jowett 1993a).

Biologists have given considerable attention, through field manuals and procedures

(Mdhous et al. 1984, OMNR 1984), to assessing and quantrfying fish habitat. Most of this work is done during sumrner low flows when conditions are deemed to be most lirniting. These flows are significantly srnaller in magnitude than those that are modeled with conventional water shce profile programs. At these low flows, bdonn features, such as rifles and pools, have a significant affect on local depths and velocities (Miller 1984).

En order to satis@ the requirements of the Fishenes Act, fish habitat becomes an intentional objective for the design not just a consequence. Imposition of habitat mctures ont0 an existing channel is not nincient. There needs to be a distinction between charme1 design and habitat restoration~enhancement. The latter may use structures so long as they are hydraulically and geomorphicdy compah'ble with the existing channel - one wodd presurne that the present channel is lacking in sufficient diversification of habitat structures and that this shucturai diversi- might naturaIiy evoIve over a long period of time. Ideally, revision of channel design guidelines in keeping with more a more nadgeometry is the ultimate engineering design target, regdess of the need for fish habitat. ui any case successful channel design must incorporate characteristics needed for fish habitat as intrinsic properties not as appended structural amendments. 3.0 STUDY OBJECTIVES Engïneers are designhg channels that are intended to match a natural pattern whde having

the ability to pass a regulatory discharge. Environmental criteria, comrnonly related to fish habita&

have been recently emphasized and thus it is anticipated that the channe1 will contain sufFicient fish

habitat features to satise various plan review agencies. Designing channels that satise structural

and fuiancial as well as these environmental criteria requires knowledge of the interaction belmeen

the water and the channel bomdasf at both hi& and low flows.

The three-dimensional nature of rivers has been describeci by fisherman for several decades

using terms like, steps, nuis, giides, d3es and pools each having distinctive geom&c, fluvial and

hydraulic characteristics. The latter two fecttures, rimes and pools, common in low-gradiem

meandering gravel-bed channels, have been extensively studied over the years but have not been

adequately incorporateci into the channel design process. incorporation of pool-rme sequences

directly into the design should provide a fiamework by wkch to successfùlly interpret the

interaction between water flow patterns and the complex three dimensionai boundary shape

obsemed to be stabIe over long periods of tirne.

Various geometric (2,Y, W, S,, di), fluvial (u, u., k,y,, S,) and hydraulic (ahT, hg, hfiV1 fl Se) variables, as illustrated in Figure 3.1, have ken shown by several authors to be significantiy

different between pools and riffies. Therefore they cannot be overlooked in a comprehensive

channel design methodology. These properties should be applicable to a range of geological

settings including that found in Southern Ontario. Figure 2. Conceptual diagram ojapool-rffle sequence illustrothg bed dope variability and hydraulic variab les (d, = residual depth, EGL = energy grade line, HGL = hydraulic grade line).

It is proposed that the rime-pool sequence should be the principal design component of low- gradient, meanderiag grave1 bed channels. Acco rdingly , the specific research goals are:

To quanti@ spedc geometrk, fluvial, and hydraulic (UV~I~~,energy losses) properties of pool-nffle sequences of low gradient, meandering, gravel-bed channels To compare these properties between two hydrologically different low-gradient, meandering, gravel-bed channels .

TO use the observations made to confïrm the importance of the pool-ritne sequence to channel design for low-gradient, meandering, gravel-bed channels . 4.0 METHODOLOGY The previous discussion has indicated a need for Merstudy of gravel-bed rivers in the

areas of river-system form and function and channel design. Bedform features, such as nfnes and pools in low-gradient, meandering, gravel-bed channels, play a signiiflcant role in the lateral and

longitudinal variab* of velocity and depth. Knowledge and understanding of the form and

fiinction of this bedform should contribute to the successfid design and construction of a new

chamel or the successfûl rernediation of unstable existing channels.

4.1 Site Seleetion In order to meet the objectives of this study it was necessary to select river reaches ht had weil developed ae-pool sequences that were considered to be fairly stable, were recognized as having superior fish habitat and that were readily accessible. Based on previous work (Amable

1995) and discussions with fkhery biologists fiom local Conservation Authorities it was decided to select a reach within each of the Grand and the Credit River watersheds with each reach assessed as containing ample fish habitat. It was assumed that ail nffle-pool sequences should behave in a similar fashion. The relation between pool-nffle hction and position dong a channel was investigated by selecting one reach in the upper region of its catchrnent and one reach in the lower region of its catchment. The former reach was the Credt River upstream of Highway 24 known as the Charles Sauriol propem (Figure 3). The latter reach was Whitemans Creek (a of the

Grand River) near the Apps Mill Nature Centre (Figure 4). Both reaches have stream flow gauges in close proximity to the study areas. Figure 3. Location of study reach on the Credit River near Cataract Figure 4. Site location of study reach on Whitemans Creek near Apps Mill Both the Credit River and Whitemans Creek are contained within glacial meltwater drainage charnels, known as spillways, associated wah the Paris moraine (Chapman and Putnam

1984). Extremely large quantities of water that flowed fiom the glaciers through these spillways were responsible for creating the present valleys in which the modern sirûams are underfit. These valieys are Wly broad and often contain cedar swamps in the lowest elevations. The geological materials within these vdeys are glacionuvial outwash deposits consisting of gravels and sands.

The north valley wall of Whitemans Creek is very steep and the south valley wall is broken into a senes of terraces (GRCA 19%).

4.2 Field Work A number of rifnes and pools were identified during an initial inspection of each site by wahgdong the thalweg of the channel and observing the patterns of the water surface and the changes in the bed elevation. This is a comrnoniy used technique for fish habitat assessrnent work

(MNR 1984). These bedform features were easily distinguishable at these sites. This is evidence that these fatures shouid be a principal design component of a river system. Since rimes occur in straight reaches, two cross-sections, one at each of the upstream and downstrearn ends, shouid suniciently define its geomorphic and hydraulic characteristics. Pools typically occur in ben& in the channel Fvith marked variations in longitudinal and lateral slopes and thus require at least three cross-sections with a common focal point to define their geomorphic and hydraulic characteristics.

Four rimes and four pools were selected in each of the study reaches. The selected pools

(P 1, P3, P4 and P6) and -es (RI,R2, R3 and R6) in the Credit River are show in Figure 5.

The selected pools (BI, B2, B6, B7) and riffies (RI, R2, R3, R4) in Whiternans Creek are shown in Figure 6 Figure 5. Location of cross-sections within the Credit River reach.

4.2.1 Topographie Survey Ternporary bench marks (TBM) made of steel fence posts (107 or 2 f 3 cm in length) were installed into the bank at key locations dong each reach. They were placed at the top and bottom of each rifne and at the focal point of three cross-sections at each pool. The top of each TBM was

Ieft approximateiy five centimeters above the ground surtace. The TBMs were located in such a way that they would be accessible during high flows and would provide an attachment point for a tape measure for cross-sectional work and for a line level to measure water levels.

A topogaphic survey was conducted using a combination of two instruments; a total station, data logger and single-optic prism pole comprised the first instrument and a laser level wÎth the receiver mounted on a customized rod comprised the second, Each survey was referenced to a benchmark adjacent to the respective gauge station, thereby miniminng vertical and horizontai error of the total station data. Vertical error of the laser level data was minimized by c'closing" onto the TBM. Data collected includzd CO-ordinatesand elevations of points in the floodplain, on bridges and roads, on the river bank, in the river channel and of the TBMs. The total station survey of the TBMs provided a Iinkage to the laser level survey of cross-sections originating at each TBM.

Cross-sections of the riffles and pools were measured using the laser level. The top and bottom of aeswere meyed in a direction perpendicular to the local channel axis. Surveys of the pools comprised at least three cross-sections because of the change in longitudinal siope through the pool. In most cases, the farthest upstream cross-section, termed the approach (Figure

2, Section 4 to 3), occurred slightly upstream of the point where there was a noticeable drap in bed elevation towards the bottom of the pool. The centre cross-section occwed as close as possible to the deepest part of the pool. The fuahest domctream cross-setion, termed the depnrture (Figure 2, Section 3 to 2), was located slightly dowIlStrearn from the point where there the bed slope

ongïnating hmthe deepest part of the pool changed noticeablably.

4.2.2 Water Surface Elevations

The elevation of the water surEace \yas measured dunng several merent flow events using

either of two methods. if the water surfàce was close to the TBMs, usually during higher flow

events, then a string level was extended fkom the TBM and the distance between the string and the

water suface was recorded. If the water surface was Meraway fkom the TBM then a laser

level was used. The Merence between the rod readïng at the top of the TBM and the reading at

the water dcewas the distance the water suface was below the top of the TBM. These

readings were Iater converted to elevations.

4.2.3 Velocity Profiles Velocity profiles were collected at a number of specific locations along each river reach;

typically at the top and bottom of rifnes and at the approach and departure points of the pools. A

minimum of five profiles were measured at each cross-section at the centre, close to each bank and

midpoint between cross-section centre and each bank. Velocity was assurned to Vary

logarithmically with depth, Accordingly veloce was measured at the following distances from the

river bed; 2.5, 4.0, 6.0, 9.5, 15 .O, 24.0, 38.0, 60.0, 95.0, 15 I .O cm where water depth permitted.

Velociv was measured with an eiectromagnetic velocity meter (Marsh-McBirney Model 2000 Flo-

Mate, range O to 6 ds,accuracy *2% of reading) at five-second intervais. A minimum of five readings was recorded at each level, more if the sequence of readings tvas highly variable.

Direction of flow was determined visuaily using a bunde of threads attached to the bracket used to mount the velocity probe onto the wadllig rod. An atternpt was made to coilect velocity data at two or more signihcandy different tvater levels and correspondhg discharge rates. 4.2.4 Substrate Particle Size An estimate of the roughness of a section of river was determined by qpan-g the size

of particles in the upper layer of the bed that was in direct contact with the water column above.

Since this study does not consider sediment transport directly it was not necessary to collect buik

samples of sediment at either the rïffies or the point bars adjacent to the pools. A method

cornmonly refereed to as the pebble count, developed by Wolman (1954) and used effectively by

Annable (1995), was used in this study. Details are provided in Yuzyk (1986). One count at a

cross-section compris& ttvo passes across the channel separated by a distance of approxïmately

one rnetre. Substrate particles were colIected by reaching straight into the water and retrieving the

fist particle that was touched by an extendeci finger. The sampler would proceed across the

channel, pardel to the cross-section axis, coilecting partides at approximately 20-cm intervals.

Once all the particies had been collecteci the b-axis of each particle was recorded. If a particle less

than 2.0 mm was encountered an estimate of its size, either silt, fine sand, medium sand or coarse

sand, was made. The Wentworth Scale (Yuzyk 1986) kvas used to define the limits of the substrate

classes. Each class was tallied to enable the computation of a frequency-by-number distribution.

4.3 Data Analysis

4.3.1 Flow Duration and Fiood Frequency Three methods were used to quant@ the hydrologic regime of the study reaches based on data obtallied fiom the Water Survey of Canada for the respective gauge. A time series plot was used to inspect the data for obvious trends and illustrate the range of flows passing through the channel. Flow duration analysis was perfonned on the average daily flow data using a cornputer program written by the author. The resu.from this analysis were used to quant@ the hydrologic differences between the Credit River and Whitemans Creek. Flood fiequency dysis of annual maximum Înstantaneous ffows assuming a Log Pearson Type III distribution was used to determine the flows with selected return periods. The 1:lS yr retum period is commonly used to approximate the banl6ull flow in non-urban channels.

4.3.2 Geomorphie Characteristics of RiRles & Pools Topographie data of cross-sections at pools and riffles were compiled as input data to a cornputer prograrn dento calculate, for a given water nrrface elevation, the area, wetted preimeter, water dcewidth, hydraulic radius and maximum depth. The algorithm divided the cross-section into thin vertical siices to account for the uneven bed topography. These topopgrahrc data were also used to determine longiturlin=il bed slopes of the pools and riffles. The longitudinal bed slope of pools required two values, the bed sloping towards (in the direction of flow) the deepest part of the pool (termed the 'kpproach" slope) and the bed slophg away fiom the deepest part of the pool (termed the "departurei7 slope). The slope of the point bars, perpendicular to the thalweg through the pools, was also calculated.

Water surface elevations and topographic data were used to determine the water surface slope for the riffles during a range of flows. The water surface slopes for the pools were determined in conjunction with the veloc* profile data.

4.3.3 Velocity Distribution and Energy Losses The velocity profile data were plotted in a cross-sectional and longitudinal fomat. The former illustrated the spatial relationships between adjacent measurement points within a profüe as well as the spatial relationship between adjacent profiles. The latter demoastrated the typical velocity profile and was used to determine the shape of the profle adjacent to the bed. Mean velocity, mean depth, Froude number (using mean velocity and mean depth) were calcdated for each data set.

The energy coefficient, a, was calcdated using Equation 2.16. Each velocity profile was considered to be the centre of a panel within the cross-section. The location of the velocity measurernent (u~)was comidered to be the centre of a rectangle with an area Ai flength 1, height hi)

(Equation 2.1 1) (Figure 7).

I

Figure 7. Discretization ofthe vetocity rneasurements in the cross-section used to cafcufutethe energy coeflicient.

The total head at each cross-section (H,) was caiculated using Equation 2-12 and the

Merence between the total head at adjacent cross-sections in either a pool or rime was defined to be the total head loss (hT) (Equation 2.13). This total head loss, hn was considered to comprise losses due to grain roughness (h,) and form roughness (hh The friction factor, f; (Equation 4.1) and the local slope of the energy grade he, SJ (Equation 4.2 by rearranging Equation 2.5) were determined for each cross-section. Head loss due to grain roughness (Equation 4.5) was calculated using the arithmetic mean energy dope (Equation 2.14a). The head loss due to form roughness (hj) equaled the ciifFerence between total (hT) and grain (hg)head loss. 5.0 RESULTS and DISCUSSION

5.I Hydrologie Setting The hydrologie regime of the Credit River and Whiternans Creek were describecl and

compared using time series plots of the last thirty years (1967-1996) of average daily flows, flow

duration analysis of the daily flow data and a flood fiequency analysis of mual maximum

instantanmus flows (1967-1996).

The time series plots for both reaches are illustrated in Figure 8. The flows in Whitemans

Creek were fiequently greater than 20.0 m3/s while the flows in the Credit River were rarely above

this value. Neither times series indicated any signincant long-term trends that may indicate

changes in in the catchents above these locations. The differences in flow magnitudes

between these reaches may be partially attnbuted to the size of their catchent areas; 383 km' for

Whitemans Creek and 205 km2 for the Credit River.

The flow duration and flood Frequency analyses are presented in Figures 9 and 10

respectively and are SUnmanzed in Table 11. The fIow duration analysis was used to quanafy the

flow regime that the reach bed was subjected to on a daily basis. This was in addition to the

approach commonly taken which was to calculate the 1.5 year return period discharge, assumed to

approximate banl6ull flow, using a flood fiequency analysis (Leopold et al. 1964, Rosgen 1993,

Annable 1995). However, both analyses were performed as each has their value in describing the flow regime through a reach. The average daily flow that was equaied or exceeded 50% of the tune was larger in Whitemans Creek than in the Credit River by a factor of 1.7. The 1 -5-year return period flow was also larger in Whitemans Creek by a factor of 2.6. These factors were in the range of the ratio of catchment areas of 1.9. - -!

1967 1972 1 977 1982 1987 1992 1997 Year

Figure 8. Time series plot of average daily flows for Whitemans Creek and Credit River (Flow data obtained nom WSC Gauges 02GB008 and 02HB001 respectively).

Table II. Summmy of thejlow regime ûfthe study reaches (al1 values me m3/s)- 1 1 Credit 1 Whitemans 1 River Creek AVERAGE DAILY FLOW Muiimum 0.436 0.164 ._.____...._...... _...... ~-~~*..-*~~.**...... _.___...~Uimum ...... 29.7 74.7 Flow Duration 16% 2.37 7.17 50% 1 -44 2.48 84% I .O2 1.O5

I Minimum 1 8-92 Maximum 35.4 84.9 Flood Frequency

During 1995 and 1996, the Credit River and Whitemans Creek were visited times respectively to collect either water level or velocity data. These visits were plotted on the

1995- 199 6 tirne series of average daily Row in Figures 11 and 12 which illustrate the range of flows that occurred for each reach during the two field seasons. FIows in 1995 were Iow iimiting the arnount of water level and veloc* data that could be collected. The flows that occurred during

May and June 1996 were considered to be the upper limit of flows for which velocie mnanirements could be safely coliected by wading. The values of the flows during these visits and their correspondkg flow duration percentages are listed in Table 12. Velociq data were collected for flows ranging between 0.80 - 3.47 m3/s at the Credit River and between 0.63 - 7.20 m3/s at

Whitemans Creek. Water level data were collected for flows ranging between 1.O 1 - 7.93 m3/s at the Credit River and between 1.O 1 - 3 5 -2 rn3/s at Whitemans Creek. Assuming that bankfid flow is in the vicinity of the 1.5 year rehmi period flow (Leopold et a!. 1964, Annable 1999, then the velocity data collected was for flows much lower than the banl6ull flows for both the Credit River

(17.1 m3/s) and Whitemans Creek (44.3 m3/s). The highest flow du~gwhich water levels were measured at Whitemans Creek, 35.2 mS/s, was close to the estimated

banldull flow of 44.3 m3/s. However ît was observed that the water level was slightly higher in

elevation than the tops of the point bars indicating that the bankm flow was in fkct closer to 35

m5/s than 44 m3/s at this site.

Table 12. Summary of occasions when velocity and water level data were collected at the study reaches @DF = average daily jlow. m3/s, FDA% = percentage of time when daily fiow wes equaled or exceeded).

13-JUIL-96 2.81 il 1::: 28-Jw-96 5.32 2::: 16-Ju-96 2.06 21 -9 29-Jw-96 4.55 27.6 minimum 0.80 97.3 Minimum 0.63 95.7 maximum 3.26 Maximum 35.2

5.2 Valley and Reach Geometric Characferistics The topographie data coilected during the total station survey and measured fiom 1: 10,000 digitai Ontario Base Maps (OBM) were used to describe the reach characteristics (Table 13).

Whitemans Creek had slightiy larger reach characteristics than the Credit River. Using strearn gradient, sinuosity, entrenchment and width:depth ratio and referring to the Rosgens classi£ïcation system presented in Table 3, both reaches were described as a "C" type channels (C-type in 4 categories, E-type in 3 categories, F-type in 2 categories). This classification correctly predicted the presence of welldehed riffles and pools in both reaches.

Pools are commonly found in the ben& of meandering channels and the cross-sectional symmetry of the pools are skewed altematively towards the lefl and the right (hcing downstream) as illustrateci in Figures A-1 9 to A-22 (Cr& River) and B- 19 to B-22 (Whitemans Creek). Two

.< "leWY and two "right" pools were studied in the CredÏt River while one "leW and three "nght" pools were studied in Whitemans Creek. Geomorphic and hydrauIic properties are not expected to be different between a left and right pool since they may be considered symmetric about the focaI point of the radius of cwature. However, to emphasize the meandering characteristic of the channel, typical "left" and "right" pools rather than a single mical pool cross-section should be included in channel construction drawings .

Table 13. Sumrnaw of reach characteristics

Feature Source Credit River Whitemans Creek Vailey gradient (%) OBM 0.20 0.33 Stream gradient (%) Survey 0.18 0.27 Sinuosity Calcdated 1.4 1.6 Vailey length (m) Survey 683 989 Stream length (m) Survey 96 1 1562 Entrenchment Survey/OBM 2.9 4.2 1 WidthDepth ratio Survey 1 18 20

5.3 Geometric and Fluvial Characterktics of Pools and R@es Longitudinal bed elevation, water elevation and particle substrate data were used to quant@ the geornorphic characteristics of the selected riffles and pools of the Credit River and

Whitvmans Creek. Bed and water slope data for the pools and rimes of the CredÏt River and tlrhitemans Creek are presented in Tables A- 1 and B- 1 respectively. The bed cross-section for the rimes and pools are illustrated in Figures A-1 to A-4 (Crdit River rinles): Figures A-I9 to A-22

(Credit River pools), Figures B-2 to B-4 (Whittemans Creek riffles) and Figures B- I9 to B-22 memans Creek pools). A summary of these data are listed in Table 14. Table 14 Bed and water surface sIopesfor r~flesand pools in the study reaches (af f values reported as %).

~e&.re Slope Credit River Whitemans Creek Reach Bed 0.18 0.27 Rimes Bed 0.63 0.65 Water 0.4 1 0.61 Pools Inter-pool 0.33 0.20 Approach 6.7 5.4 Departure -5-3 -1 -9 Bar 19.1 16.6 Water 1.2 0.68

Bed and water slopes were of similar magnitude between the two study reaches despite: their different hydrologie regimes. It is clear that the bed slope in these channeIs was not uniform.

Aithough it was not the intent of this thesis to study the longitudinal variation in bed elevation as was done by Richards (1976) the bed slope may be suffciently described by conside~gthe bed slope associated with pools and rifiles. The relationship demonstrated by Annable (1993), that bed dope Uicreased in magnitude fiom pool to reach to rime, was observed in Whitemans Creek but not in the Credit River. This may be because only selected pools and rimes were shtdied and the connectivity of all bedfomis in each reach was not part of this methodology.

The three-dimensional structure of the pools was clearly delineated by the large approach, deparhue and bar slopes relative to the reach and riffie slopes (Table 14). Bar slopes are similar to those mea~u~edby Miller (1984) and Annable (1995). This pool structure has significant implications on the energy equation since bed elevation (Z) adwater depth (Y) vaq considerably within a short distance.

It is often assumed that the channel bed and water surface slopes are sufEcientIy sdarto be interchangeable in equations involvuig slope. This may be acceptable in the ri88es but is not valid in the pools due to the variation in bed slope within a single bend. It was expected that the water surfàce slope across the pool would be smaller than that in the nffIes but the opposÏte appears to be the case (Table 14). This may be attn'buted to the dlsample nurnber of pool data as well as Zess than optimal placement of the TBMs in the pools for the measurernent of water surfàce elevation.

Residuai depth (Figure 2? d,) was calculated when one of the selected riffles kvas immediately downstrearn of the pooI. This occurred in two instances in the Credit River (P6-R6 residuai depth = l.8Om, P3-R2 residual depth = 1.46 m) and once in Whiternans Creek (B6-R4 residual depth = 1-8 lm). Lisle (1 987) proposed the use of residual depth as a pool dimension independent of water depth but discussed the use of residual depth as a means of quantifjing the effect of channel modifications on the river bed. Unfortunately there was Little data found for this dimension and this made cornparison to other river systems difficult. However, residual depth could be a useful dimension in the design of riverbeds. Once the strearn gradient (constrained by valley dimensions) and sinuosity are knom and the initiai placement of rifiles are proposed. the residual depth d aid in the vertical placement of the pools.

Bed roughness was estimated fiom the substrate particle size analysis presented in Tables

A-3 (Credit River) and B-3 (Whitemans Creek) and summarized in Table 15. Substrate particle size distributions are illustrated in Figures A-3 1 (Credit River) and B-3 1 (Whrtemans Creek). The substrate of both reaches was well within the grave1 range (2.0 - 64 mm) and was significantly (t- test, 95% level) Iarger in the rifnes than in the pools as expeded (Leopold et ai. 1964; Keller,

1971 Lisle, 1979; Knighton, 1984; Milne 1982, ClBord, 1993). The d50 metric, combined with the hydraulic radius, was used to calculate the friction fàctor for each cross-section. Table 15. Substrate particle sizes (mm) for rifles and pools in the study reaches

Velocity distribution data were used to calculate the fluvial and hydradic characteristics of pools and nnles in the Credit River and Whitemans Creek. An atternpt was made to coilect as many velocity distribution data as possLble within one day at each reach in order facilitate cornparison of these variables within and between rifaes and pools. The occasions when velocïty distn'bution data were collected at each rime and pool are listed in Table 16

Table 16- Listing ofoccasions when velociiy data were collected at speci-ed cross-sections within the stuc& reaches

- -- Credit River ~hitem&sCreek Location Dates Location Dates R6U, D 22 Aug 95, 10 Jun 96 R4U, D 28 Sep 95,30 May 96 24 Aug 95,11 Jun 96 R3U, D 28 Sep 95,30 May 96 24 Aug 95,11 Jun 96 R2U, D 28 Sep 95,30 May 96 RlU, D 30 May 96 B1(162), (104) 26 Jun 96 B2(158), (104) 27 Jun 96 86(52), (3 1 O) 29 Jun 96 B7f 106). (14) 29 Jun 96

Working in a range of flow conditions was possible in the riffles but not in the pools, so two visits were made to most of the riffles, compared to a single visit to each of the pools. It was observed that if the product of maximum velocity and depth was less than 1.O then one could safely stand in the channel.

Cross-sectional survey data, water level data and veloc* data (cross-section and profile formats) are presented in Appendices A and B. The distance between velocity profiles was approximately 200 cm and the height of the profles ranged from 10 to 100 cm. Variability of the five velocity measurements was fieqyently less than 10% but rangeci as hi& as 30% close to the bed. Sixteen hydraulic variables are summarized in Tables A-2 (Credit River) and B-2

(WhÏtemans Creek). There were eleven variables that were significantly different (t-tm 95% level) between pools and rimes in both reaches (Table 17). Nine variables were signiflcantly different (t-test, 95% level) between the reaches for the pools and and four were signi.ficantiy different for the nffles (Table 18).

Table 17. . Cornparison offluvial and hydraulic variables between pools and riflles at each of the stuciy reaches (signrficantiy dinerent ut 95%. larger values are shadea').

1 Pools 1 Riffles 1

VAratio V:d ratio 1/s

Whitemans Creek

Widîh

- Grain energy slope dm VA ratio V:d ratio 1/s Table 18. Cornparison Offluvïal und hydralic variables between the study reaches for pools and for rifles (significantly diflerent at 95%. Larger values are shaded).

Variable Units Rifnes Particle size (dso) m 0.03 1 Shear velocity m/s 0.046 Velocity dope I/s 0.128 ( Velocity intercept ds 0.588

Table 17 shows that there was no significant difference in the water nirface width between ritnes and pools in the Credit River while there was a Merence in Whitemans Creek. Similarly &ere was no Merence in the velocitydepth ratio and the shear velocicy between riffles and pools in

Wbitemans Creek while there was a Merence in the Credit River. The pools in both reaches were deeper than the rimes and therefore had larger hydraulic radii. The substrate was finer in the pools and the fiction factor mialler and energy dope shallower in the pools than in the nffles. It can be seen fiom Equation 4.1 that the £iiction factor, f; is inversely proportional to relative roughness,

Wdso . It foilows that the derfriction factors of the pools were due to the larger relative roughness values of 22.2 and 20.4 in the Credit River and Whitemans Creek pools, cornpared to

10.O and 7.6 in the Credit River and Whiternans Creek riffles. The energy grade line slope (grain roughness, S& was shallower in the pools than in the riffles, which was in agreement to that found by Yang (1971b). Jowett (1993b) suggested that the ve1ocity:depth ratio and Froude number codd be differentiated between rifnes and pools and applied numerical criteria to these parameters (see

Table 4). Whïie these cnteria were not applicable to these data, the relative merences between rifBes and pools were in general agreement (v:hi < v:dae , Froud-i < Froudw, ), with only the ve1ocity:depth ratio in the Credit River being sigdhntly Merent.

There was more variability in the pools between reaches than in the rinles (Table 18).

However, aii of these variables, except width, include a velocity term. The clifferences betn-een the flowdependent variables are therefore due to the range of flows in which the data was collected.

The rmxhurn flow in Whitefnan~Creek was 7.20 m3/s as compared to 3.47 m3/s in the Credit

River.

Those variables that were common between Tables 17 and 18 were listed in Table 19.

There was no single hydraulic or geometnc variable that was significantly different bbetween pools and =es and between reaches. Shear velocity, cross-sectional area, median particle size and energy slope showed the most variability.

Table 19. Cornparison offluvial and hydraulic variables beiween the study reaches and between pools and riffles (Y indicates there was a significant djgerence for that variable in that categoryl

Variable Between riffles Between riffles Between Between and pools of the and pools of pools? riffles? Credit? Whitemans? (Table 5-7) (Table 5-7) (Table 5-8) (Table 5-8) Area Y Y Y Particle size (dso) Y Y Y Average depth Y Y Maximum depth Y Y Width Y Y Hydraulic radius Y Y Friction factor Y Y

Shear velocity Y Y Y Grain energy dope Y Y Y VAratio Y Y V:d ratio Y Y Velocity dope Y Y Velocity intercept Y Y Average velocity Y Froude nurnber Y 5.4 HydrruCic Charucterilstics of Pools and Rzjfjfles The energy coefficient, a,did not Vary between nfnes and pools in either of the reaches

nor vary between riBies and between pools (Table 20). However, the values were much larger

than 1.0 and were often greater than 2.0 suggesting that the velocity distribution within pools and

nffles is not uniform. This calculation combined with the observation that the variability of the

veloce meaSuTernents close to the bed.

Table 20. Cornpurison af the energy coeflcient, 4 between rzfles and pools

Credit River Whitemans Creek Mean Min Max Mean Min Max Pools 1.98 1.61 2.95 1.78 L.45 2.66 Riflles 1.81 1.43 2.38 1.76 1.20 3.42

The velocity profiles adjacent to the bed (20 - 30% of the water depth) closely followed the logarithmic relationship of Equation 2.9a between velocity and height above the bed. Average correlation coefficients were greater than 0.75 and commonly greater than 0.90. The shear velocity caiculated fiom the velocity promes (Equation 2.9b) correlated well wïth the cross-sectional shear velocity (Equation 2.3b) (Figure 13). The dope of the regession line was slightiy higber in the rimes than in the pools in both reaches (Table 2 1).

Table 2 1. Relationship behveen cross-section and velocity pro/ile shear velocity figure 13). Credit River 1 Whitemans Creek ope if Slope I 3 Pools 0.55 0.90 0.64 0.87 Riffles 0.78 0.92 0.71 1 0.92 Bedfom

0 Pools - - Pools Ries - Ries

0.05 0.1 O Velocity profile shear velocity (mls)

Figure 13. Linear relationship (through the origin) between the velocity pronle shear velocity and the cross-section shear velocity. Sand grain roughness, k,, (Equation 2.10) was highly variable in both reaches (Table 22)

although the mean value was greater than the mean particle size as expected. The ratio between k,

and d50was slightly larger than 6.8 reported by Bray (1980). The sand grain roughness is larger in the rifnes than the pools in Whitemans Creek as expected. The high variabile in the Credit River pools may explain why the mean value is higher than in the rifnes. The roughness iength was comparable to that suggested by Carling (1992) but the relationship to particle size was much derthan 15.

Table 22. Cornparison between grain roughness, roughness length and median particle size. (mean values with range in brackets. all dimension in mm).

Credit River Whitemans Creek Variable Pools mes Pools Riflles k 403 308 296 415 (192672) (84.598) (1 09-435) (2 13-632) Y0 15 1I 12 15 (6.428) (2.8-20) (7.0- 15) (6.4-27)

&O 23.1 3 1.4 24.1 42.3 kJds0 17.4 9.8 12.3 9.8 dsd~o 1.5 2.9 2 .O 2.8

The slope the hydrauiic and energy grade lines (Table 23) were not significantly different between the rimes and pools of either the Credit River or Whiternans Creek. This was due to the extremeIy high variance and sdlsamples nurnbers. This variance was probably associated with the measmement of the water depth CY) since the rneasurement error associated with the bed elevation (2)and the velocity head was considered to be withùi acceptable toIerances. Table 23. Cornparison between the dopes (??A)of the hydraulic and energy grade Zines.

Credit River Whitemans Creek

Pools 0.47 0.22 7 0.63 0.34 7 (O. 174.78) (0.30-1.1) Riffles 0.98 0.52 4 0.68 0.70 4 (0.40-1 -6) (0.057-1.7)

EGL Pools 0.48 0.2 1 7 0.64 0.35 7 (0.2 14.80) (031-1.1) mes 1.O 0.52 4 0.75 0.76 4

The total head loss &) and the head loss due to grain roughness Og) (TabIe 24) were calculated fiom rneasured variables. The head loss due to fom roughness was taken to be the difference between total head loss and that due to grain roughness. Form roughness was the larger component of the total head loss for mesand pools in both reaches, nipporting the conclusions drawn by Miller (1984). The coefficient K was calculated using Equation 2.16.

Table 24. Surnrnary ofthe civerage total, grain and fornt head Zosses for rmes and pools in the studj reaches.

Head Loss Credit Whitemans (Table A4) (Table B-4) Total 0.263 0.191 Grain 0.06 I 0.040 Form 0.202 O. 15 1 K 31 16 Pools Total 0.105 0.228 Grain 0.003 0.027 Form O. 102 0.20 1 K 1I 7

Total head losses and grain roughness losses are both significantly greater in the rifnes than in the pools of the Credit River. There were no differences between the pools and riftles of White-

Creek. Grain roughness accounts for approximately 20% of the total head loss in the fisand approximately 8% in the pools. Although there appears to be a dinerence between the magnitude of the form roughness coefficient (K), this could not be shown statistically. Tthere was no clear pattern between bedforms and head loss or between reachs and total head loss.

Applying Equation 2.1 1 between two cross-sections revealed that as stage increased the water depth difference (AY) decreased and the energy term merence (A(~v'/z~))increased as the bed elevation merence remaineci constant. The head losses tbat were caidated at the sarne reach during two different flows are listed in Table 26. A clear pattern of form roughness being dominant at low flows and grain roughness being dominant at higher flows was not evident.

Table 25- Variation in head losses with average daily flow for the rifles in the study reuches (remaining riffs and all pools were not visited ut higher lfows).

Change Change ADF h~ hg ht in hT in 6, (m3/s> (m) ("/O) (Oh) 1

Whitemans R2 1 0.63 0.077 32 6 8 0.99 1.28 5.1 0.076 41 5 9 R3 0.63 0.16 3 O 70 0.45 1.73 5.1 0.072 52 48 R4 0.63 0,335 Il 89 1.01 0.27 5.1 0.339 3 87

5.5 Pool-Riff Sequence as the Principal Design Compnnent When designing a system it is necessary to clearly define the fiinctional elements of that system (Orbom and Anderson 1986). If selected correctly, an element will have distinctive properties that differentiate it fiom other elements. Duplication of the properties of each element shodd lead to the successfd construction of the system. One of the fiindamental equations in open-channel hydraulics is the energy equation (Equation 2.12). A channel structure that strongly influences the variables within this equation must be recognized as a significant component of the

system. In the case of low-gradient, meandering gravel-bed rivers, it has been proposed that the

firnctional elements are pools and riffles. Their ease of identification in the field lends support to this proposai.

Analysis of the geornorphic and hydraulic data clearly Uidicates that nfnes and pools have

distinctive properties. Tfierefore, chamel design methods that have objectives to menatural featwes, including î%h habitat, shoutd be based on the concept that pools and rifles are the principal design components of Iow-gradient, meandering gravel-bed rivers. The methods of

Newbury & Gaboury (1993) best fit this concept but the reasoning behind the dimensioning of the constructeci nffle are lacking. While their methods produce a complex three-dimensional fluvial environment, detds on the hydraulic specifications would be useful in addition to the geornetric specifications provided in the manual. Rosgens (1995) classification system provides additional information on the pool-riffIe seqyence by linking the features of the valley, the river, the reach and the bedfom. However, care mut be given to the proper and consistent use of bedform and substrate tenninology. For example bar-pools and rimes do not occur in bedrock channels.

A variation of the design methodology of Newbury and Gaboury (1993) is proposed (Figure 14). ft is assumed that Ït has been previously decided that channel works are required and that the purpose of the works includes rn-g the natural features such as fish habitat. hitially, information needs to be collected on the characteristics of the upstream contributing catchement, the hydrologie regime derived fiom that cathcment and the topography and geology of the vdey containing the study reach. Once it is determined that the pool-ri£ne sequence is appropriate, sufficient information is available to layout an initial pool-ae sequence

(Figure 15). The geometry of a cross-setion for each type of pool and for the rimes may be developed such rhat the design discharge dlhave a water surface elevation the corresponds to the top of the bank The location of key points of the fie and pool, being linked to the stream gradient and plan geometry, may be set. The flow su~llfnaryd provide information on dominant discharge and water surface elevation and aid in the establishment of the linear dimensions such as width and depth.

bedfonn sequence - channel work required /zz\ - must maxîmke natural features

Catchment & Flow Analysis Configure & Dimension (iand use, elevation, , bedform sequence in al1 3 duratiodfiequency) dimensions (plan, profile. cross-section)

VaIley & Channel Analysis @rofile/slope, belt width, terraces, bed~bankmaterial) Evaluate Hydraulics through bedform sequence (energy, head losses) Identify & establish topographie location of ail constraints (valiey waU, infrastnicture...)

SuIItrnarize geometric & fluvial variables for fisheries assessrnent

Figure 13. Recommended design procedure for poo l-riflle sequences in low-gradient gra~el-bed channels.

The hydraulic properties of the pools and rifnes such as energy coefficients and the evaluation of grain and form losses may be used to estimate the velocity and depth over a range of flows. If necessary the proposed vertical and horizontal alignment may need to be adjusted in order that the velocity and depth at al1 points in the reach are withio a predefined range. Once this has been completed, the geometry and hydraulics of the reach may be Summarized for use in assessing the suitability of the reach for a given fish comrnunity. it is assumed that the designed channel will provide a majority of the natural features possible given the constraints of topography, geology and hydrology. Fom roughness will be dominant at Low flows providing a wide range of fluvial conditions. Grain roughness will be dominant at flow approaching the dominant discharge.

Above this discharge, sediment transport would be initiated but the dimensions of the pool-nnle sequence are expected to be mzintained.

Cross Sections

Future water surface Profile ------

C EleMtion set at these Iocations EIevation adjusted at these locations

Figure 15. illustration ofthe method to configure and dimension the pool-riffle sequence. The standard-step method, using the energy equation, to determine the depth of water progressing in the upstream direction is savalid. However, the locations of the cross-sections must be carefblly selected to coincide with the longmiciinal variation in total energy. The pool- rifile sequence may be used as a template to satisthis cnferion. The head losses, gr- form and expansion/contraction (between pools and Rffles) must be carefiiuy evaluated at each cross- section. Coincidentally, the use of this template with the standard-step method should provide sufficient velocity, depth and substrate data to sufficiently descnbe fish habitat dong the reach. 6.0 CONCLUSIONS & RECOMMENDATIONS The present research focused on the pool-rBle sequence as the principal design component of low-gradient, meandering gravel-bed channels. Selected pools and rifnes were studied in two reaches fiom neighboring watersheds with dishnctly dif5erent hydrologic regimes. The following conclusions were dram fiom the results of this study:

The pool-rifle sequence is a dominant three-dimensional structure of low-gradient meandering pvel-bed channels.

Rifnes and pools may be eady distinguished by the geometric characteristics.

Subçtrate particle size, determined from the pebble count method, is a usefûi technique to measure bed roughness.

Previously developed equations are applicable to calculate the fiction -or and grain head loss

PartÏtioning of total head loss between grain and form roughness appean to be stage depeodent but requires Merwork to clar*

The energy coefficient is signifïcantly different from 1.O

The velocity profile adjacent to the bed is lognormal. The parameters derived from these profiles, y,, u* and k,are ail within the ranges proposed in the literature. As a resuit of the foregoing research there are several recommendations that may be put foah to Merdefine the function of the riffle-pool sequence as the principal design cornponent of low-gradient, meandering gravel-beds .

Detede the connectivîty of pools and riffles and the associated head Ioss due to expansion/con.traction Detede the stage dependency of the geomorphic and hydrauiïc characteristics of pools and rinles CareWIy measure the partitioning of the head loss between grain and form losses Instrument rifnes and pools to measure water level and velocÎty distributions at or near bankfiill stage

Separate backwater analysis procedures into those where valley processes are dominant () and those where channel process are dominant (flom-s below bank£ÛIl stage) Mom backwater analysis cornputer programs to more accurately account for detaiied energy losses between bedforms and test it on an appropriate reach 7.0 REFERENCES ASCE Task Force on Bed Forrns in Alluvial Channels. L 966. Nomenclatureof bed forms in alluvial channels - Joudof Hydrauiics Division 92(3):5 1-64.

Amble, W.K.. 1995. Morphological relationships of nual water courses in Southwestern Ontario for use in naturai channel designs. Masters Thesis, University of Guelph, Guelph, Canada.

Beebe, John, T.. 1996. Fluid speed variabdity and the importance to managing fish habitat in rivers. Regulated River: Research and Management, 12: 63 -79.

BIench, T.. 1969. Mobile-bed fluviology. University of Alberta Press. Edmonton Canada- 168 p.

Brice, J.C.. 1975. Atrphoto interpretation of the form and behaviour of alluvial rivers. Report to the US.Army Research Office.

Bray, D. 1. 1972. Generalized regime-type analysis of Alberta gravei-bed rivers. Ph.D. thesis, Department of Civil Engineering, University of Albe- Edmonton, Canada

Bray, D. 1.. 1980. Evaluation of effective bomdary roughness for gravel-bed rivers. Canadian Journal of Civil Engineering. 7:392-397.

Bray, D. 1.. 199 1. Resistance to flow in grave-bed rivers. Tecbnicd Report HTD-9 1- 1, Canadian Society of Civil Engineering, Hydrotechnical Division. 95 p -

Bray, D. 1. and Church, M.. 1980. Armored versus paved grave1 beds. Journal of the Hyddics Division. 106(11):1937-1 940.

Carling, P.A. 1992. In-stream hvdanilics and sediment transport. in Callow, C. and Petts, G., [ed] The Rivers bdbook: hydrological and ecological principles. Oxford, Basil BIackwell, Pages 101-125.

Chang, H. H.. 1983. Energy expendinire in curved open cham&. Journal of Hydrauiic Engineering. 109(7):10 12-1022.

Chang, H.H.. 1984a. Arialysis of river meanders. Journal of Hydralic Engineering. 11 O(l):3 7-50.

Chang, H.H.. l984b. Variation of flow resistance through curved channels. Journal of Hydrauiic Engineering. 1 lO(12): 1772-1782.

Chang, H.H. 1988a. Cornputer-aided design for channelization. Journal of Hydraulic Engineering. Change, H.H.. 1988. F111via.l processes in river engineering- Kreiger Publishing Co., Malabar. Florida.

Chapman, L. J. and Putnam, D. F.. 1984. The Physiography of Southern Ontario. Third Edition, Ontario Geologicd Survey Special Volume 2, Toronto, Ontario Ministry of Natural Resources.

Chow, V. T.. 1959. Open-Channel Hydraulics. McGraw-Hill Book Company, New York.

Chwch, M. 1992. Channel morphologv and ~olom.in CaLlow, C.and Petts, G., [eq The Rivers Hancibook: hydrological and ecoiogicai principles. Oxford Bad Blackwell, Pages 126- 143.

Clifford, N.J.. 1990. The formation, nature and maintenance of nffle-pool sequences in gravel- bedded rivers. PhD Thesis, University of Cambridge, Cambridge, U.K..

Clifford, N. J,, Robert, A. and Richards, K.S. 1992. Estimation of flow resistance in gravel- bedded rivers: A physical explanation of the multiplier of roughness length. Earth Surface Processes and Landforms 17: 11 1 - 126.

CWord, N.J. 1993a. Differential bed sedimentology and the maintenance of rime-pool sequences. Catem 20:447-468.

Clifford, N.J. 1993bh. Formation of riffie-pool sequences: field evidence for an autogenic process. Sedimentary Geology, 85 :3 9-5 1.

Davis, W.M. 18 99. The geographical cycle. Geographical Journal 14:48 1-504.

Dietrich, W.E. and Smith J.D. 1983. influence of the point bar on flow through cwed channels. Water Resources Research, 19(5): 1 173- 1192.

Dotling, R. 1968 Occurrence of pools and rifiles: an element in the quasi-equilibriurn state of river channels. Ontario Geography 2:3-11.

Dunne, T. and Leopold, L.B. 1978. Water in environmental planning. San Francisco: W.H. Freeman Co. 8 18 p.

Dury, G.H.. 1969. Relation of morphometry to nuioff fieyency. in Water Earth and Man (ed. R. J. Chroley), Methuen , London, England. p 4 18 -43 0.

Environment Canada. 1994. Assessrnent of benefits of subwatershed planning and naturalizing strearn systems. Ferguson , RI. 1977. Meander sinuosity and direction variance. Geological Society of America Bddin 88:212-214-

Galay, V.I 1987. Erosion and in the Nepd Himilaya. Water and Energy Comm. Sec., Kathmandu Nepal.

Galay, V.J. 1907. Basic Stream geomorphology for highway applications. Chapter 9 in MT0 Drainage Management Manual ( 1997)

Gilbert, R.O. 1987. Statistical methods for environmental poilution rnodo~g.Van Nostrand Reinhold, New York, 3 20 p.

Grand River Conservation Authonty . 1976. information report for Apps Mill Conservation Area.

GntMhs, G.A.. 198 1. Flow resistance in coarse gravel bed rivers. Journal of Hydraulics Division, 107(7):899-918.

Griffiths, G.A. 1987. Form resistance in gravel channels with mobile beds. Joumal of Hydraulic Engineering 115(3):340-355.

Hydraulic Engineering Centre. 1982. HEC-2 Water Surface Proflies: Users Manual. U-S Army Corps of Engineers, Davis, California

Hendersoq F.M. 1966. Open Channel Hydraulics. Macmillan Publishing Co., hc., New York

Hey, R.D. 1978. Determinate hydraulic geometry of river channels. Journal of Hydraulic Engineering, 104(6):869-885.

Hey, R.D. 1988. Bar form resistance in gravel-bed rivers. Journal of Hydraulic Engineering, 1l4(l2): 1498-1508.

Hey, RD. and Thome, C.R. 1983. Accuracy of surface samples fiom grave1 bed material. Jou.of Hydraulic Engineering, 1Og(6) :842-85 1.

Hortoq R.E.. 1945. Erosional development of streams and their drainage bains: Hydrophysicai approach to quantitative morphology, Geologicai Society of America Bullebon, 56:275-370.

Hulsing, H., Smith3 W. and Cobb, E.D. 1966. Velocity-head coefficients in open channels. Geological Survey Water Supply Paper 18 69-C, U.S. Govemment Printing Office, Washington.

James, C.S. 1994.. Evduation of methods for predicting bend loss in meandering channels. Jodof Hydraulic Engineering, l20(2):245-25 3.

Jin, Y., Steffler, P .M. and Hicks, F.E.. 1990. Roughness effects on flow and shear stress near the outside bank of curved chamel. Journal of Hydraulic Engineering, 116(4):563-577.

lohamesson, H. and Parker, G. 1989 Velocity redistribution in meandering rivers. Journal of Hydrauiic Engineering, 115(8):1019-1039.

Johnson, P.A. and Heil, T.M. 1996. Uncertainty in estirnahg badddl conditions. Water Resources Bulletin, 3 2 (6): 1283 - 129 1.

Jow-ett, 1. 1993a. River hydraulics and inStream habitat modelhg for river biota. in "Waters of New Zealand", New Zealand Hydrobiologicai Society.

Jowett, I.G.. 1993b. A method of objectively idenmg pool, nui and mehabitats form physical measurernents. New Zealand Journal of Marine and Freshewater Research, 27:241- 248,

Keller, E.A,. 197 1. Areal sorting of bed-load material: the hypothesis of velocity reversal. Geological Society of Arnerica Bulletin, 82:753 -756.

Keller, E.A.. 1978. Pools, riffles and channelization. Environmenta1 Geology, 2(2): 119- 127.

Keller, E.A. and Melhom, W.N.. 1978. Rythmc spacing and ongin of pools and rimes. Geological Society of America Bulletin, 8 9:723 -73 0.

Keller, E.A. and Florsheim, J.L.. 19%. Velocity-reversal hypothesis: A mode1 approach. Earth Surfàce Processes and Landfonns, l8:733-740.

Kellerhals, R. and Bray, D .I. 1971. Sampling procedures for coarse fluvial sediment.. Journal of the Hydanilics Division, 97(8):1 165- 11 8 0.

Kellerhals, R., Church., M. and Bray, DI.. 1976. Classification and analysis of river processes. Journal of the Hydraulics Division, 1O2(7):8 13-829.

Khan, M.S. 1971- evaluation with lirnited data in the arid region of West Pakistan. Proceedings of the Central Treaty Organization Seminar on Evaluation of Water Resources cvith Scarce Data, Tehran, Iran.

Knighton, D. 1984. Fluvial forms and processes. Edward Arnold, New York.

Lamoureux, N., Souchon, Y. and Herouin, E.. 1995 Predicting veloci~ffiequency distributions in stream reaches. Water Resources Research 3 1(9):2367-2375. Lane, E.W. 1955. The importance of fluvial geomorphology in hydraulic engineering. Proce. ASCE, 8 1, Paper 745, p 17.

Langbein, W.B. and Leopold L.B.. 1966. River rneanders - theory of minimum variance. Geological Survey Professional Paper 422H, United Sttates Government Printùig Office, Washington.

Langbein, W.B. and Leopold, L.B. 1968. River channel bars and dunes - Theory of kinematic waves. US.Geological Survey Professional Paper No 422-L.

Leopold, L.B., Wohan, M.G. and Miller, J.P. 1964. Fluvial process in geomorphology. Freeman and Co., San Francisco, California

Leopold, L.B.. 1994. A View of the River. Harvard University Press: Cambridge, Massachusetts.

Leopold, L.B. and Maddock, T.. 1953. The hydraulic geometry of Stream channels and sorne physiographic implications. Geological Survey Professional Paper 2 52, United Sttates Government Printing Office, Washington.

Lisle, T.E.. 1979. A sorting mechanism for a nffle-pool sequence. Geological Society of America Bulletin Part II, 90: 1142-1 157.

Lisle, T.E.. 1987. Using "residud depths" to monitor pool depths independently of discharge. Res. Note PSW-394. Berkeley, CA. Pacific Southwest Forest and Range Experiment Station, Forest Service, US. Department of Agriculture, 4 p.

Mihous, R.T., Wagner, D.L. and Waddle, T. 1984. Users guide to the physical habitat simulation system. Instream Flow Information Paper Il, USDI Fish. Wddl. Serv., Office of Biol. Serv. FWS/OBS-8 1/43.

Miller, B.A. 1984. Modelling low flow hydraulics in alluvial channels. Ph.D. dissertatioo, University of Illinois, Urbana, 284 p.

Milne, J.A.. 1982. Bed-material size and the ae-pool sequence. Sedimentology, 29:267-278.

Ministry of Natural Resources, 1984. Manual of Instruction - Aquatic Habitat Inventory Surveys.

Ministry of Natural Resources. 1994. Natural Channel Systerns - An Approach to Management and Design. Queens Printer, Ontario

Ministry of Transport, 1992. Drainge manual. Queais Printer, Ontario Ministry of Transport, 1997. Drainge Management Manual. Queens Printer, Ontario

Molinas, A. 1 994. Users Manual for BRI-STARS . National Cooperative Highway Research Program, Project HRl5- l 1A82 p. + Appendix.

Mollard, J.D.. 1973. Air photo interpretation of fluvial features. Proceedings of the Symposium on Fluvial Processes and Sedùneatation Hydrology Symposium No. 9, Inland Waters Directorate, Canada Department of the Environment.

Mollard, J.D. and Janes, J.R. 1984. Airphoto interpretation and the Canadian landscape. Energy, Mines and Resources Canada.

Mosfey, M.P. 1982. A procedure for characterising river channels- Water and Miscellaneous Publication No. 32, Christchurch Water and Soil Science Centre, New Zealand-

National Research Council. 1992. Restoration of Aquatic . National Academy Press, Washington, D .C ..

Newbuy, R.W. and Gaboq, M.N.. 1993. Stream analysis and fish habitat design - A field manual. Newbury Hydraulics Ltd.

O'Neill, M.P. and Abrahams, A.D.. 1984. Objective identification of pools and fies. Water Resources Research, 20(7):92 1-926.

Orsborn, J.F. and Anderson, J.W. 1986. Stream irnprovements and fish response: A bio- engineering assessment. Water Resources BulIetin 22(3):3 8 1-3 88.

Parker, G. and Sutherland, A. J. 1990. Fluvial . Jomal of Hydradic Research, 28(5):529- 544.

Platts, W.S., Megahaq W.F. and Minshall, G.W.. 1983. Methods for evaluating Stream, riparian and biotic conditions. General Technid Report INT-138, Intermountain Forest and Range Experiment Station, Forest SeMce, U.S . Depariment of Agriculture, 69 p

Prestegaard, K-L..1983. Bar resistance in grave1 bed strearns at banI6uIl stage. Water Resources Research, 19(2):472-476.

Rhodes, D .D. . 1977. Tbe b-f-m diagram: Graphical representation and interpretation of at-a- station hydraulic geometry. American Jouranl of Science, 277:73 -96.

Richards K.S.. 1976. The morphology of ri£lle-pool sequences. Earth Surface Processes 1 :7 1-88. Richards, K.S.. 1976. Channel width and the riffle-pool sepence. Geological Society of Arnerica Bulletin, 87:883-890.

Rosgen, D .Le.1995. A classification of natural rivers. Cataena 22: 169- 199.

Rosgen, D .L. 1996. Applied River Morphology. Wildland Hydrology, Colorado.

Robert, Andre. 1990. Boundaq roughness in coarse-grained channels. Progress in Physical Geography 14(1):42-69

Schumm, S.A.. 1963. A tentative classification of channels. US.Geological Survey Circular 477, Washington.

SchqS.A. 1977. The Fluvial System. John Wiley & Sons, New York, New York

Selby, M.J. 1985. Earths Changing Surface: An Introduction to Geomorphology. Olaord University Press, Oxford, U.K.

Shuveil, CS. 1986. Pitfalls of physical habitat simdation in the instrearn fIow incremental methodology. Canadian Technical Report of Fisheries and Aquatic Science No. 1460.

Singh, K.P. and Broeren S.M., 1989. Hydraulic geometry of streams and Stream habitat assessment. Journal of Water Resources Plauning and Management. 1 15 (9583 -5 97.

SM, J.B. and Yang, C.T., 1972. Hydraulic geometry and low streadow regirnen. Water Resources Center Research Report 54, Universisr of Illinois.

Tinkler, K.J. 1970. Pools, rïfEles and meanders. Geological Society of Arnerica Bullet.. 8 1547- CE3

Thornbury, W.D.. 1969. Principals of Geomorphology. 2nd edition, John Wiley, New York.

Williams, G.P. 1978. Bank-full discharge of rivers. Water Resources Research l4(6): 1 141 - 1154.

Wohl, E.E., Vincent, K.R. and Mexritis, D.J.. 1993. Pool and rif3e characteristics in relation to channel gradient. Geomorphology 6:W- 110.

Wolmau, M.G.. 1954. A method of sampiing coarse river bed material. Transactions American Geophysical Union, 35 (6): 95 1-

Wolman, M.G. and Leopold, L.B.. 1957. River flood plains: Some observations on their formation. USGS Professional Paper No. 282-C. Wolman, M.G. and Miller, J.P.. 1960. Magnitude and fiequency of forces in geomporphic processes. Journal of Geology 68(1):54-74.

Yang, C .T.. 197 la. On river meanders. Journal of Hydrology, l3(3):23 1-25 3.

Yang, C .T. 197 1b. Formation of rifnes and pools. Water Resources Research, 7(6): 1567-1 574.

Yu& T.R. 1986. Bed material sampling in gravel-bed streams. Environment Canada, Water Survey of Canada. Sediment Srirvey Section, IWD-HQ-WRB-S S-8 6-8.

Zimtnerman, C. and Kennedy, J.F. 1978. Transverse bed slopes in curved alluvial streams. JodofHydraulics Division 104(1):33-48 APPENDIX A - CREDIT RNER DATA Table A- 1. Surnmary of the bed and waier elevations and slopes of riffles and pools for the Credit River.

GDF RlU RlD R2U R2D R3U R3D R6U R6D I Bed Elevation 381 ,058 380.755 381.354 38 1 .O02 382.003 381,674 383.547 383.128 Distance 46.6 Water Elevation 1 .O1 381.275 381.142 381.769 1.22 381,311 381.249 381.804 :E 381.354: 381.2591 381,834 381,784 381,884 381.297 381.189 381.829 fram velocitv data:

Bed Slo~e 0.627%

Bed Elevation 380,976 380.294 380.345 Disîance 6.7 17.7

1 Water Elcvutioii 381.560 381,480

L Appronch Slope 6.7% 10.2% Departure Slope -5.3% -0.3% Table A.2. Summtuy of liydraulic conditions in riilles and pools of the Credit River (highlighted variables significantly différent nt 95%),

Pooh Avg Std n Min Max StdiAvg AVP V 0.3 1 0.07 8 0.21 0.41 0.21 Avg d 0.44 0.08 8 0.34 0.49 0.17 Max d 0.98 0.29 8 0.58 1.51 0.30

V:d 0.73 O. 18 8 0.42 0.91 0,25 V:A 0.066 0.03 8 0.03 0.12 0,42 U* 0.032 0.007 8 0.020 0.043 0.23 Velocity dope 0.131 0.054 8 0,078 0.236 0.4 1 Velocitv interceot 0.569 O. 167 8 0.372 0.900 0,29

Velocity dope O. 128 0.088 14 0.034 0.347 0.68 Vclocity intercept OSH8 0.346 14 0.167 1.373 0.59 Table A-3. Summary of substrate particle sïze for the riffles and pooIs of the Credit River

RIFFLES Ohtile R6U R6D R3U R3D R2U R2D RI U R1D 16 5.2 16.3 12.4 8.8 6.1 4.5 15.7 13.9 50 -----24.3 3 1.7 29.8 36.9 35.2 32.0 30.1 30.0 84 61 -3 72.5 76.8 806 88.6 stdev 3 -6 2.1 2.5 3-2 4.2 4.7 2-31 2.1

Table A-4. Swmq of the total, grain and form head losses for the rimes and pools of the Credit River (ADF = averaged daily flow).

Date ADF h+ hg hr hg hr K (m3/s) (m) (m) (m) ("/O) ("/a)

11-Ju-96 3.26 0.181 0.033 0.248 Avg 0.263 0.061 0.202 Stdev 0.5751 0.045 0.566

1 P6 1pi;i3~-96 Stdev

1 t Il

I III

l Ill I I II

1 III ! i II

t III 1 I il

1 III I I II

1 III I I II

I III I l II

I III I ! II

IlII l III

I III I III

I III I III

I Ill l III

I III I III

1 III l III

1 III l III

1 III i III

1 III i I Il

I III I I II

I III

I III

+\ III l 1 I

III

III

III

Ill

Ill

III

IIl

III

III

III

III /

UPSTREAM CROSS-SECTION DOWNSTREAM CROSS-SECTION jvio 1.10 . I l I IlIII I I I 17- -

2 3 4 5 6789 2 3 45 2 3 4 5 6 789 2 3 45 0.10 0.10 Height frorn bed (m) Height frorn bed (m)

Figure A-12. Logarithmic velocity profiles mcasured at R1 at Crcdit River on 11 Jun 1996.

UPSTREAM CROSS-SECTION DOWNSTREAM CROSS-SECTION

I 2 3 4 5 6789 2 3 45 2 3 4 5 6789 2 3 45 0.1 0 0.1 0 Height from bed (m) Height from bed (rn)

Figure A-14. Logantiimic velocity profiles measured nt RZ at Credit River on I 1 Jun 1996.

DOWNSTREAM CROSS-SECTION i''j :r i''j UPSTREAM CROSS-SECTION

I 2 3 4 5 6789 2 3 45 0.10 Height from bed (m) Height from bed (ml

Figurc A- 16. Logaritiimic velocity profiles measured at R3 ai Credit River on 1 1 Jun 1996. UPSTREAM CROSS-SECTION DOWNSTREAM CROSS-SECTION 77

2 3 4 5 6789 2 3 45 2 3 4 5 6789 2 0.10 0.10 Height from bed (m) Height from bed (m) - 1m~v~lle~~~ab)

Figure A-17. Logaritiiniic velocity profiles rneasured at R6 rit Credit Rivcr on 22 Aug 1995. UPSTREAM CROSS-SECTION DOWNSTREAM CROSS-SECTION

1-1-

2 3 4 5 6 789 2 3 45 2 3 4 5 6 789 2 3 45 0.10 0,10 Height frorn bed (m) Height from bed (m)

Figure A-1 8. Logarithniic velocity profiles measured at R6 at Credit River on 1 1 Jun l996 I I -

41% L riI 1 I 1 -

I 1 L.~O

lLI Section 342 - velocitv vrofifed !i Slope between 342 and 2 = +10.2%

I Section 2 - veiocitv orofikd I Slope between 2 and 74 = -0.3%

I Section 74 I l 1 I 10.00 Distance from left bank (m)

Figure A- 19. Cross section plots of pool P 1 at Credit Riva upstream of Hwy 24. edion 290 - velocity profiled j Slope between 290 8 245 = +12.3%

Slope beîween 245 & 223 = -14.4%

10.00 Distance from left bank (rn)

Figure A-20. Cross section plots of pool P3 at Credit River near Caledon. 381 .O0 edion 80 - veloQv profiled Slope between 80 and 126 = +1.7%

Slope between 126 and 160 = -1.5%

10.00 20.00 Distance from left bank (rn)

w-=-1

FigureA-2 1. Cross section plots of pool P4 at Credit River upstream of Hwy 24. Slope between 198 & 156 = +2.7%

381 .O0 ection 156 I

Slope between 156 & 126 = -5.1 Oh

5.00 10.00 Distance from let bank (m)

Figure A-22. Cross section plots of pool P6 at Credit River near Caledon. Distance from left bank (m)

4.00 8.00 Distance from left bank (m)

Figure A-23. Location of velocity lneasurements at P 1-Credit River on 13 June 1996.

UPSTREAM CROSS-SECTION DOWNSTREAM CROSS-SECTION ii-il-ITI 'Tm[---lll-ml~

2 3 4 56789' 2 3 4 56789' 0.10 1 ,O0 Height from bed (m)

Figure A-27. Logaritlimic velocity profiles measured at P 1 at Credit Rivcr on 13 Junc 1996. UPSTREAM CROSS-SECTION DOWNSTREAM CROSS-SECTION 'iI'71-m 7)

2 3 4 56789' 2 3 456789' 0.1O 1 .O0 Height from bed (m)

Figure A-28. Logarithinic velocity profiles measured at P3 at Credit River on 12 lune 1996. UPSTREAM CROSS-SECTION

1.30

1 1 2 3 4 56789 2 3 4 5 6789 2 3 456789' 2 3 4 5 6789' 0.1 0 1 .O0 0.1 0 1 .O0 Height from bed (m) Height from bed (m)

Figure A-29. Logarithmic velocity profiles measured at P4 at Credit River on 12 Juiie 1996. UPSTREAM CROSS-SECTION DOWNSTREAM CROSS-SECTION '.O0 0-oiml

2 3 4 5 6789' 2 3 4 56789' 2 3 4 5 6 789' 2 3 456789' 0.1 O 1 .O0 0.1O 1 ,O0 Height from bed (m) Height from bed (m)

Figure A-30. Logariti~micvelocity profiles nicasured at P6 at Credit River on 12 lune 1996, 31.2 50 1 i 74.2 84 1

SDEV I! 8.8

I I I

Grave1 Cobble Boulder

FKEFPOOLS

I 84 1 55.1 SDEV / 5.6

10 1O0 Particle size (mm)

Figure A-3 1. Subsûate particle Ne for pools and riffles of the Credit River. APPENDM. B - WHITEMANS CREEK DATA 2s-sa I owsa I owua I wza I vor-za I sçr-za I toi-ra I zur-ra I zrz-ra I W 1 I

- %O0 ['O %9€EaO %L8 1'0 %Z6Za0 % 190'5 %91S'O %9£0'0 %Z8 Z'O %6PEa0 %l1 l'O

% 1P6'0 %EPP'O Table 8-2, Suinmary of hydraulic conditions in rimes and pools of Whitem~nsCreek (highlightcd van~blessignificuntly diftèrcnt ut 95%)

Pools 1 Avg 1 Std 1 n 1 Min 1 Mar 1 SldlAvg Avg V 1 0.51 1 0.14) 8 1 0,361 0.69) 0.27

Max d 1.O2 0.26 8 0.72 1.42 0.25 Widih 15.06 4.33 8 8.20 19.10 0.29 Arca 7.68 2.69 8 4.80 12.69 0.35 R 0.244 0.08 8 0.165 0,371 0.32 Alpha 1.78 0.43 8 1.45 2.66 0.24 V :d 1.15 0.46 8 0.64 1.96 0.40 V: A 0.075 0.03 II 0.03 O. 14 0.45 U* 0,055 0.021 8 0.031 0,079 0.37 Vclocity slopc 0.201 0.074 II 0.125 0.308 0.37 Vclocity intercepl 0.922 0,280 8 0.666 1.315 0.30 r“2 0.75 0.11 8 0. SR 0.86 0.14

lu* 1 0.0621 0.0201 14\ 0.0261 0.0911 0.321 (vclocity slopo 1 0.210l 0.076( 141 0.067 1 0.3281 0.361 hclocitv intcrccot 1 0.903 1 0.338 1 141 0.3331 1.3041 0.351 Table B-3. Summa~~of substrate particle sizes for the rifnes and pools of Whitemans Creek.

RIFFLES O/otile R4U R4D R3U R3D R2U R2D RI U R1D 16 6 -2 11.8 13.9 13.1 11.4 1.6 18.3 18.2 50 25.5 33.5 49.4 50.3 53.3 37.6 49.7 43 .O 84 69-4 74.4 103.1 103.5 106.5 86-8 97.3 86.1 stdev 3-4 2.5 2.8 2.9 3 -3 13-1 2.3 2.2

I POOLS I

Table B-4. Sumary of the total, grain and forrn head losses for the riEles and pooIs of Whitemans Creek (ADF = average daily flow).

Date ADF h~ hg hr hr K (m3/s) (m) (m) (m) ("/O) ("/a)

RIFFLES RI 30-May-96 5.06 0.281 1 0.058 0.223 21% 79% 13 R2 28-Sep-95 0.63 0.0771 0.024 0.052 32% 68% 14 R2 30-May-96 5.06 0.0761 0.031 0.045 41% 59% 2.0 R3 28-Sep95 0.63 0.157 0.047 0.1 10 30% 70% 20 R3 30-May-96 5.06 0.072 0.037 0.035 52% 48% 1.3 R4 28-Sep-95 0.63 0.335 0.038 0.297 11% 89% 45 R4 30-May-96 5.06 0.339 0.044 0.294 13% 87% 13 Avg 0.191 0.040 0.151 15.5 Stdev 1 0.115 0.010 0.109 14.7

POOLS BI 26-Jun-96 7.20 0.0271 0.016 0.011 59% 41% 0.53 B2 27-Jun-96 6.44 0.442 0,024 0.418 5% 95% 12 B6 29-Jün-96 4.55 0.182 0.011 0.170 6% 94% 17 B7 ----29-Jw-96 4.55 0.26 1 0.056 0.206 21% 79% 4.8 Avg 0.228 0.027 0.201 8.6 Stdev 0.173 0.0201 0.168 7.3 III I lil I

III 1

III I

III I

III I

III I

Ili l

III I

III I

III I

III 1

III I lil l

III 1

II! i

II1 I

II! Id

I l

III I I

III 1 1

III I t

III I 1

III i 1

III I I

III l l

III I 1

III 1 1

"III 1l /

4.00 8,OO 12.00 Distance from left bank (m) I

-

-

-

I -- J III---1 1 0.00 4,OO 8.00 12.00 16.00 Distance from left bank (m)

Figure B-10. Location of velocity measurements at R4-Whitemans Creek on 28 Sept 95.

UPSTREAM CROSS-SECTION DOWNSTREAM CROSS-SECTION 1.50 1 1.50 I I IIIIII I I I II-n - 1 1 1 1 1 111 1 1 I III- 1.40 - - - - 1.30 - - - - 1.20 - - 1.10 - -

2 3 4 5 6789' 2 3 456709' 2 3 4 5 6 709' 2 3 4 5 6 789' 0.1 O 1 .O0 0.1 O 1 .O0 Height from bed (m) Height from bed (m)

Figure B-12,Logarithmic vclocity profiles measured at RI at Wliitcmaiis Creck on 30 May 1996.

UPSTREAM CROSS-SECTION rmr-'-'7DOWNSTREAM CROSS-SECTION

709' 2 3 4 56789' 2 3 4 5 6789' 0.1 O 0.1O 1.O0 Height from bed (m) Height from bed (m)

Figure B-15. Logarithrnic vclocity profiles measured at R3 at Wiitenians Creek on 28 Sept 1995.

UPSTREAM CROSS-SECTION DOWNSTREAM CROSS-SECTION

2 3 4 5 6789' 2 3 4 5 6789' 2 3 4 5 6789' 0,1O 1 .O0 0.10 1 .O0 Height from bed (m) Height from bed (m)

Figure B- 17. Logarithmic velocity profiles nleasured at R4 at Wiiteniaiis Creek on 28 Sept 1995. UPSTREAM CROSS-SECTION DOWNSTREAM CROSS-SECTION 1.60 mp~-l

2 3 4 56789 2 3 4 5 6789' 2 3 4 5 6789' 2 3 456789' 0.10 1 .O0 0.10 1 .O0 Height from bed (m) Height from bed (m)

Figure B- 18, Logarithrnic velocity profiles nieasured at R4 at Wiitcmans Crçek on 30 May 1 W6. Section 212 Slope between 21 2 & 162 = 0.093%

Slope between 162 & 104 = 1.8%

0.00 4.00 8.00 12.00 16.00 20.00 24.00 28.00 32.00 36.00 Distance from left bank (m)

Figure B-19.Cross section plots of pool B 1 at Whitemans Creek at Apps Mill. Section 158 - vekcitv protiied Slope between 158 & 104 = +4.8%

Slope between 104 & 68 = -1.2%

0.00 4.00 8.00 12.00 16.00 20.00 24.00 28.00 Distance frorn Ieft bank (m)

Figure B-20. Cross section plots of pool B2 at Whitemans Creek at Apps Mill. I -

4

-

Section 33 0 - velacitv ~rofiled Slope between 310 & 340 = +4S%

-

-

-

Section 52 - veloatv ~rofiled l 1 I I 0.0 4.0 8.0 12.0 16.0 20.0 24.0 28.0 32.0 Distance from left bank (rn)

Figure B-21. Cross section plots of pool B6 at Whitemans Creek at Apps Mill. Stope between 1û6 & 78 = +i2%

Slope between 78 & 14 = -4.7%

l 1 Section 14 - velocitv ~rofiled 1 I

0.00 4.00 8.00 12.00 16.00 20.00 24.00 28.00 32.00 36.00 Distance from left bank (m)

Figure B-22. Cross section plots of pool B7 at Whitemans Creek at Apps Mill.

UPSTREAM CROSS-SECTION DOWNSTREAM CROSS-SECTION - 1 1 1 I III I 1 l Ill -

2 3 4 5 6789' 2 3 456789' 2 3 4 56789' 2 3 456789' 0.1O 1.O0 0.10 1 .O0 i-îeight from bed (rn) Height from bed (m)

Figure B-30. Logarithmic velocity profiles measured at B7 at Whitemans Creek on 30 May 1996, R lFFLES

Sand Gravel I

POOLS % 1 mm

l

SDEV

10 100 Particle size (mm)

Figure B-3 1. Substrate particle size for pools and nnles of Whitemans Creek.