Hydraulics of Open Channel Flow. An Introduction Basic Principles, Sediment Motion, Hydraulic Modelling, Design of Hydraulic Structures

625 Pages·2004·3.56 MB·English

Preface to the first edition
The book is an introduction to the hydrauHcs of open channel flows. The material is designed
for undergraduate students in civil, environmental and hydraulic engineering. It will be assumed
that the students have had an introductory course in fluid mechanics and that they are familiar
with the basic principles of fluid mechanics: continuity, momentum, energy and Bernoulli
principles.
The book will first develop the basic principles of fluid mechanics with applications to open
channels. Open channel flow calculations are more complicated than pipe flow calculations
because the location of the free-surface is often unknown a priori (i.e. beforehand). Later the
students are introduced to the basic concepts of sediment transport and hydraulic modelling
(physical and numerical models). At the end of the course, the design of hydraulic structures is
introduced. The book is designed to bring a basic understanding of the hydraulics of rivers,
waterways and man-made canals to the reader (e.g. Plates 1-32).
The lecture material is divided into four parts of increasing complexity:
Part 1. Introduction to the basic principles. Application of the fimdamental fluid mechanics
principles to open channels. Emphasis on the application of the Bernoulli principle and momen
tum equation to open channel flows.
Part 2. Introduction to sediment transport in open channels. Basic definitions followed by sim
ple applications. Occurrence of sediment motion in open channels. Calculations of sediment
transport rate. Interactions between the sediment motion and the fluid motion.
Part 3. Modelling open channel flows. The two types of modellings are physical modelling and
numerical modelling of open channel flows:
• Physical modelling: application of the basic principles of similitude and dimensional analy
sis to open channels.
• Numerical modelling: numerical integration of the energy equation; one-dimensional flow
modelling.
Part 4. Introduction to the design of hydraulic structures for the storage and conveyance of
water. Hydraulic design of dams, weirs and spillways. Design of drops and cascades. Hydraulic
design of culverts: standard box culverts and minimum energy loss culvert.
Basic introduction to professional design of hydraulic structures. Application of the basic
principles to real design situations. Analysis of complete systems.
Applications, tutorials and exercises are grouped into four categories: applications within the
main text to illustrate the basic lecture material, exercises for each chapter within each section,
revision exercises using knowledge gained in several chapters within one section and major
assignments (i.e. problems) involving expertise gained in several sections: e.g. typically Part I and
one or two other sections. In the lecture material, complete and detailed solutions of the applications
xii Preface to the first edition
are given. Numerical solutions of some exercises, revision exercises and problems are available
on the Internet (Publisher's site: http://www.bh.com/companions/0340740671/).
A suggestion/correction form is placed at the end of the book. Comments, suggestions and
critic are welcome and they will be helpful to improve the quality of the book. Readers who find
an error or mistake are welcome to record the error on the page and to send a copy to the author.
'Errare Humanum Est'.^
^ To err is human.
Preface to the second edition
Hydraulics is the branch of civil engineering related to the science of water in motion, and the
interactions between the fluid and the surrounding environment. The beginnings of civil engin
eering as a separate discipline are often linked to the establishment of the 'Ecole Nationale des
Ponts-et-Chaussees' (France) in 1747, and it is worth noting that its directors included the famous
hydraulicians A. Chezy (1717-1798) and G. de Prony (1755-1839). Other famous professors
included B.F. de Belidor (1693-1761), J.B.C. Belanger (1789-1874), J.A.C. Bresse (1822-1883),
G.G. Coriolis (1792-1843) and L.M.H. Navier (1785-1835). In a broader sense, hydraulic engi
neers were at the forefi-ont of science for centuries. Although the origins of seepage water was long
the subject of speculations (e.g. 'Meteorologica' by Aristotle), the arts of tapping groundwater
developed early in the antiquity: i.e. the qanats developed in Armenia and Persia. Roman aque
ducts were magnificent waterworks and demonstrated the 'know-how' of Roman engineers (see
Problem 4 and Plates 1 and 2). The 132 km long Carthage aqueduct was considered one of the
marvels of the world by the Muslim poet El Kairouani. In China, a major navigation canal system
was the Grand canal fed by the Tianping diversion weir. Completed in BC 219, the 3.9m high,
470 m long weir diverted the Xiang River into the south and north canals allowing navigation
between Guangzhou (formerly Canton), Shanghai and Beijing (Schnitter, 1994).
Hydraulic engineers have had an important role to contribute although the technical chal
lenges are gigantic, often involving multiphase flows and interactions between fluids and bio
logical life. The extreme complexity of hydraulic engineering is closely linked with the
geometric scale of water systems, the broad range of relevant time scales, the variability of river
flows from zero during droughts to gigantic floods, the complexity of basic fluid mechanics
with governing equations characterized by non-linearity, natural fluid instabilities, interactions
between water, solid, air and biological life, and Man's total dependence on water.
This textbook is focused on the hydraulics of open channel flows. One of the greatest challenges,
in teaching open channel hydraulics, is for the students to understand that the position of the fi*ee-
surface (i.e. water depth) is often unknown beforehand (Plates 1, 2, 5, 6, 8, 10, 11, 12, 16, 17, 18,
23, 24, 25, 28 and 30). In contrast, pipe flow calculations are performed with known pipe diame
ters and hence cross-sectional areas. Most open channel flow calculations are not straightforward.
They may require solving a cubic equation (e.g. Bernoulli equation) and perform iterations (e.g.
normal flow depth). One basic illustration is the sluice gate problem (Fig. 1.1). Considering a sluice
gate in a smooth horizontal channel, the input conditions may be the upstream depth, channel
width and flow rate. What are the downstream flowd epth and the force acting onto the gate? What
is the correct free-surface profile upstream and downstream of the gate? Explanations are available
in the text. A more detailed problem is given in the Revision exercises (Part 1).
Hydraulic engineering is an exciting discipline linking students to the basic needs of our
planet (Plates 14 and 15). This second edition was prepared especially to stimulate university
students and young professionals. Most material is taught at undergraduate levels at the
University of Queensland. The structure of the new edition is largely based upon the successful
first edition (see Comments). Updates and corrections were included. The lecture material in
xiv Preface to the second edition
c
T7—Y7—77 77—77—77—77—77—7^—77^
0 ©
Fig. 1.1. Flow beneath a sluice gate: which is the correct free-surface profile?
Part 3, modelling open channel flows was enlarged and includes two new chapters on the
modelling of unsteady open channel flows. Applications, exercises and revision problems have
been expanded. This edition contains further a larger number of illustrations than in the first
edition.
The book is complemented by Internet references (see Additional bibliography) and a new web
site {http://www.bh.com/companions/0340740671/}, while corrections and updates are posted at
{http://www. uq.edu.au/~e2hchans/reprints^ook3_2.htm}. The latter is updated and maintained
by the writer.
Comments
First published in August 1999, the textbook The Hydraulics of Open Channel Flow: An
Introduction has been designed for undergraduate students in civil, environmental and
hydraulic engineering. The textbook is used in all six continents of our planet. It has been trans
lated into Chinese (Hydrology Bureau of Yellow River Conservancy Committee) and Spanish
(McGraw Hill Interamericana). The first edition was reviewed in several well-known inter
national journals:
Professor S.N. Lane, University of Leeds, in Environmental Conservation, 27(3), 2000,
314-315.
Without a doubt, this is the best introduction to the hydraulics of open channel flow that I have
yet to read. The text deserves special credit for the explicit identification of the assumptions that
exist behind relationships, something that can be (and is) easily over-looked by students whilst
using other texts. As an introduction to the hydraulics of open channel ^o^, I would find it dif
ficult to recommend anything that could improve upon the approach adopted. My overwhelming
conclusion is that as an introduction to the hydrauHcs of open channel flow, it would be impossible
to produce a better result. This will appear on both my undergraduate and postgraduate reading
Preface to the second edition xv
lists as the core text. It is rare for me to be so readily persuaded, and Dr Chanson deserves fiill
credit for an outstanding teaching resource.
Professor P. Bates, University of Bristol, 'Changing a winning formula: the hydraulics of
open channel flow: an introduction' in Hydrological Processes, 15(1), Special Issue, 2001,
159 pp.
The ultimate test of such a textbook is whether it can be useful for a range of problems and be
accessible to a wide readership. To do this the hydraulics group at Bristol has been "road-testing"
this volume for the past three months. [...] In that time, a diverse range of queries has been
initially researched in Hubert Chanson's volume, and it has passed each test with flying colours.
All graduate and postdoctoral researchers who have used the volume have commented
favourably on its clarity and completeness, and / can think of no better recommendation than
this. This is an excellent book for undergraduate and graduate students in civil engineering inter
ested in open channel flow,a nd a very useful resource text for those interested in hydraulics out
side engineering field.
Professor W.H. Hager, ETH-Ziirich (Switz.), Wasser, Energie & Luft, Switzerland, 2000,
No. 1/2, p. 55.
Another excellent piece of work. All in all, this is a well-written and carefully illustrated book
which is useful for all civil and environmental engineers. It easily meets highest expectations.
Professor O. Starosolszky, Director, Vituki, in Journal of Hydraulics Research, lAHR, 39(1),
2001,331-332.
An original approach, which makes the book equally valuable both for students, and also prac
titioners in hydraulic engineering.
Professor M. Jovanovic, Belgrade, Urban Water, 1(3), 270.
This book stands apart from similar previously published textbooks in two ways. Firstly, its
scope has significantly been extended towards applications. Secondly, by including many exer
cises, notes, discussions, relevant photographs and appendices with additional information,
it has an original, handbook-like presentation, very convenient for quick referencing, and use
in engineering practice. Being more than a simple introductory textbook in open channel
hydraulics, this book can be strongly recommended to students and engineers.
Professor D.A. Ervine, University of Glasgow, in Chemical Engineering Research and Design,
Trans IChemE, Part A, 78(A7), Oct. 2000, 1055.
Hubert Chanson's latest book is really designed for a civil engineering readership with its
emphasis on sediment movement in rivers and also hydraulic structures for rivers and dams. All
in all, a well-constructed book with many helpful examples and explanations for the student.
Acknowledgements
The author wants to thank especially Professor Colin J. Apelt, University of Queensland, for his
help, support and assistance all along the academic career of the writer. He thanks Dr Sergio
Montes, University of Tasmania, and Professor Nallamuthu Rajaratnam, University of Alberta
for their advice and support. He acknowledges past and present students for their contributions.
He expresses his gratitude to the following people who provided photographs and illustrations
of interest:
The American Society of Mechanical Engineers
Mr and Mrs Michael and Linda Burridge, Brisbane QLD, Australia
Mr and Mrs Chanson, Paris, France
Ms Chou Ya-Hui, Brisbane QLD, Australia
Mr L. Stuart Davies, Welsh Water, UK
Dr Dong, Zhiyong, Zhejiang University of Technology, China
Ms Chantal Donnelly, Brisbane QLD, Australia
Dr Chris Fielding, Brisbane QLD, Australia
Gold Coast City Council, Australia
Mrs Jenny L.F. Hacker, Brisbane QLD, Australia
The Hydro-Electric Commission (HEC) of Tasmania, Australia
Mr Patrick James, Sydney NSW, Australia
Mr D. Jeflfery, Goulbum-Murray Water, Australia
Dr John Macintosh, Water Solutions, Australia
Dr Lou Maher, University of Wisconsin, USA
Mr J. Mitchell, Brisbane QLD, Australia
Mr Chris Proctor, Brisbane, Australia
Mr RU Hua-Chih, Taipei, Taiwan ROC
Dr R. Rankin, Rankin Publishers, Brisbane, Australia
Mr Paul Royet, Cemagref, Le Tholonet, France
Mr Marq Redeker, Ruhrverband, Germany
Sinorama-Magazine, Taipei, Taiwan, ROC.
Larry Smith, USA
Tonkin and Taylor, New Zealand
USDA, Natural Resources Conservation Service, National Design, Construction and Soil
Mechanics Center, Fort Worth, Texas
US Geological Survey, USA
Mr Peter Ward
Mr Dale Young, Australia.
The author also thanks the following people who provided him with information and assistance:
Dr Shin-ichi Aoki, Toyohashi University of Technology, Japan
Professor C.J. Apelt, Brisbane QLD, Australia
Acknowledgements xvii
Mr Noel Bedford, Tamworth NSW, Australia
Mr and Mrs Chanson, Paris, France
Ms Chou Ya-Hui, Brisbane QLD, Australia
Dr Stephen Coleman, University of Auckland, New Zealand
Concrete Pipe Association of Australasia, Sydney NSW, Australia
Mr Doug Davidson, Murwillumbah NSW, Australia
Mr L. Stuart Davies, Welsh Water, UK
Dr Michael R. Gourlay, Brisbane QLD, Australia
Mr John Grimston, Tonkin and Taylor, New Zealand
Dr D. Holloway, University of Tasmania, Australia
Mr Ralf Homung, Germany
Mr Graham Illidge, University of Queensland, Australia
Mr Patrick James, Sydney NSW, Australia
Mr D. Jeffery, Goulbum-Murray Water, Australia
Dr Eric Jones, Proudman Oceanographic Laboratory, UK
Mr Daniel M. Leblanc, Petitcodiac RiverKeeper, Canada
Mr Steven Li, Hydro-Electric Commission of Tasmania, Australia
Ms Carolyn Litchfield, Brisbane QLD, Australia
Ms Joe McGregor, US Geological Survey (Photo Library), USA
Dr J.S. Montes, University of Tasmania, Australia
Officine Maccaferri, Italy
Professor N. Rajaratnam, University of Alberta, Canada
Mr Paul Royet, Cemagref, France
Mr Craig Savela, USDA
Mr Des Williamson, HydroTools, Canada.
The author acknowledges further numerous feedback and advice on the first edition. Thanks
to all these readers.
Last, but not the least, the author thanks all the people (including colleagues, former students,
students, professionals) who gave him information, feedback and comments on his lecture
material. In particular, he acknowledges the support of Professor C.J. Apelt in the preparation
of the book. Some material on hydraulic structure design (spillway design and culvert design
more specifically) is presented and derived from Professor Apelt's personal lecture notes, while
some material on the Saint-Venant equations derived from Dr Jean Cunge's lecture notes.
About the author
Hubert Chanson received a degree of 'Ingenieur Hydraulicien' from the Ecole Nationale
Superieure d'Hydrauhque et de Mecanique de Grenoble (France) in 1983 and a degree of
'Ingenieur Genie Atomique' from the 'Institut National des Sciences et Techniques Nucleaires'
in 1984. He worked for the industry in France as an R&D engineer at the Atomic Energy
Commission from 1984 to 1986, and as a computer professional in fluid mechanics for Thomson-
CSF between 1989 and 1990. From 1986 to 1988, he studied at the University of Canterbury (New
Zealand) as part of a PhD project. He was awarded a Doctor of Engineering from the University
of Queensland in 1999 for outstanding research achievements in gas-liquid bubbly flows. In 2003,
the International Association for Hydraulic engineering and Research (lAHR) presented him the
14th Arthur Ippen Award for outstanding achievements in hydraulic engineering.
The author is a Reader in environmental fluid mechanics and water engineering at the
University of Queensland since 1990. His research interests include design of hydraulic struc
tures, experimental investigations of two-phase flows, coastal hydrodynamics, water quality
modelling, environmental management and natural resources. He is the author of four books:
Hydraulic Design of Stepped Cascades, Channels, Weirs and Spillways (Pergamon, 1995), Air
Bubble Entrainment in Free-Surface Turbulent Shear Flows (Academic Press, 1997), The
Hydraulics of Open Channel Flows: An Introduction (Butterworth-Heinemann, 1999) and The
Hydraulics of Stepped Chutes and Spillways (Balkema, 2001). He co-authored a fifth book
Fluid Mechanics for Ecologists (IPC Press, 2002), while his textbook The Hydraulics of Open
Channel Flows: An Introduction has already been translated into Chinese (Hydrology Bureau of
Yellow River Conservancy Committee) and Spanish (McGraw Hill Interamericana). His publi
cation record includes over 200 international refereed papers and his work was cited over 800
times since 1990. Hubert Chanson has been active also as consultant for both governmental
agencies and private organizations.
He has been awarded six fellowships from the Australian Academy of Science. In 1995 he
was a Visiting Associate Professor at National Cheng Kung University (Taiwan, ROC) and he
was Visiting Research Fellow at Toyohashi University of Technology (Japan) in 1999 and 2001.
Hubert Chanson was invited to deliver keynote lectures at the 1998 ASME Fluids Engineering
Symposium on Flow Aeration (Washington DC), at the Workshop on Flow Characteristics
around Hydraulic Structures (Nihon University, Japan 1998), at the First International
Conference of the International Federation for Environmental Management System IFEMS'Ol
(Tsurugi, Japan 2001) and at the 6th International Conference on Civil Engineering (Isfahan,
Iran 2003). He gave invited lectures at the International Workshop on Hydraulics of Stepped
Spillways (ETH-Ziirich, 2000) and at the 30th lAHR Biennial Congress (Thessaloniki, Greece,
2003). He lectured several short courses in Australia and overseas (e.g. Taiwan, Japan).
His Internet home page is {http://www.uq.edu.au/~e2hchans}. He also developed technical
Internet resources {http://www.uq.edu.au/~e2hchans/url_menu.html} and a gallery of photo
graphs web site {http://www.uq.edu.au/~e2hchans/photo.html} that received more than 2000
hits per month since inception.
Glossary
Abutment Part of the valley side against which the dam is constructed. Artificial abutments are some
times constructed to take the thrust of an arch where there is no suitable natural abutment.
Academie des Sciences de Paris The Academic des Sciences, Paris, is a scientific society, part of the
Institut de France formed in 1795 during the French Revolution. The academy of sciences succeeded
the Academie Royale des Sciences, founded in 1666 by Jean-Baptiste Colbert.
Accretion Increase of channel bed elevation resulting fi-om the accumulation of sediment deposits.
Adiabatic Thermodynamic transformation occurring without loss nor gain of heat.
Advection Movement of a mass of fluid which causes change in temperature or in other physical or
chemical properties of fluid.
Aeration device (or aerator) Device used to introduce artificially air within a liquid. Spillway aeration
devices are designed to introduce air into high-velocity flows. Such aerators include basically a deflec
tor and air is supplied beneath the deflected waters. Downstream of the aerator, the entrained air can
reduce or prevent cavitation erosion.
Afflux Rise of water level above normal level (i.e. natural flood level) on the upstream side of a culvert
or of an obstruction in a channel. In the US, it is commonly referred to as maximum backwater.
Aggradation Rise in channel bed elevation caused by deposition of sediment material. Another term is
accretion.
Air Mixture of gases comprising the atmosphere of the Earth. The principal constituents are nitrogen
(78.08%) and oxygen (20.95%). The remaining gases in the atmosphere include argon, carbon dioxide,
water vapour, hydrogen, ozone, methane, carbon monoxide, helium, krypton ...
Air concentration Concentration of undissolved air defined as the volume of air per unit volume of air
and water. It is also called the void fi*action.
Alembert (d') Jean le Rond d'Alembert (1717-1783) was a French mathematician and philosopher. He
was a friend of Leonhard Euler and Daniel Bernoulli. In 1752 he published his famous d'Alembert's
paradox for an ideal-fluid flow past a cylinder (Alembert, 1752).
Alternate depth In open channel flow, for a given flow rate and channel geometry, the relationship
between the specific energy and flow depth indicates that, for a given specific energy, there is no real
solution (i.e. no possible flow), one solution (i.e. critical flow) or two solutions for the flow depth. In the
latter case, the two flow depths are called alternate depths. One corresponds to a subcritical flow and the
second to a supercritical flow.
Analytical model System of mathematical equations which are the algebraic solutions of the fundamen
tal equations.
Apelt C.J. Apelt is an Emeritus Professor in Civil Engineering at the University of Queensland
(Australia).
Apron The area at the downstream end of a weir to protect against erosion and scouring by water.
Aqueduct A conduit for conveying a large quantity of flowing waters. The conduit may include canals,
siphons, pipelines (Plates 1 and 2).
Arch dam Dam in plan dependent on arch action for its strength.
Arched dam Gravity dam which is curved in plan. Alternatives include 'curved-gravity dam' and 'arch-
gravity dam'.
Archimedes Greek mathematician and physicist. He lived between BC 290-280 and BC 212 (or 211).
He spent most of his life in Syracuse (Sicily, Italy) where he played a major role in the defence of the
Glossary xxi
city against the Romans. His treaty 'On Floating Bodies' is the first-known work on hydrostatics, in
which he outUned the concept of buoyancy.
Aristotle Greek philosopher and scientist (BC 384-322), student of Plato. His work Meteorologica is
considered as the first comprehensive treatise on atmospheric and hydrological processes.
Armouring Progressive coarsening of the bed material resulting from the erosion of fine particles. The
remaining coarse material layer forms an armour, protecting further bed erosion.
Assyria Land to the north of Babylon comprising, in its greatest extent, a territory between the
Euphrates and the mountain slopes east of the Tigris. The Assyrian Kingdom lasted from about BC
2300 to 606.
Avogadro number Number of elementary entities (i.e. molecules) in one mole of a substance:
6.0221367 X lO^^moP^ Named after the Italian physicist Amedeo Avogadro.
Backwater In a tranquil flow motion (i.e. subcritical flow) the longitudinal flow profile is controlled by
the downstream flow conditions: e.g. an obstacle, a structure, a change of cross-section. Any down
stream control structure (e.g. bridge piers, weir) induces a backwater effect. More generally the term
backwater calculations or backwater profile refer to the calculation of the longitudinal flow profile. The
term is commonly used for both supercritical and subcritical flow motion.
Backwater calculation Calculation of the firee-surface profile in open channels. The first successful cal
culations were developed by the Frenchman J.B. Belanger who used a finite difference step method for
integrating the equations (Belanger, 1828).
Bagnold Ralph Alger Bagnold (1896-1990) was a British geologist and a leading expert on the physics
of sediment transport by wind and water. During World War II, he founded the Long Range Desert
Group and organized long-distance raids behind enemy lines across the Libyan desert.
Bakhmeteff Boris Alexandrovitch Bakhmeteff (1880-1951) was a Russian hydraulician. In 1912, he
developed the concept of specific energy and energy diagram for open channel flows.
Barrage French word for dam or weir, commonly used to described large dam structure in English.
Barre de Saint-Venant Adhemar Jean Claude Barre de Saint-Venant (1797-1886), French engineer of
the 'Corps des Ponts-et-Chaussees', developed the equation of motion of a fluid particle in terms of the
shear and normal forces exerted on it (Barre de Saint-Venant, 1871a,b).
Barrel For a culvert, central section where the cross-section is minimum. Another term is the throat.
Bazin Henri Emile Bazin was a French hydraulician (1829-1917) and engineer, member of the French
'Corps des Ponts-et-Chaussees' and later of the Academic des Sciences de Paris. He worked as an assist
ant of Henri P.G. Darcy at the beginning of his career.
Bed-form Channel bed irregularity that is related to the flow conditions. Characteristic bed-forms
include ripples, dunes and antidunes (e.g. Plates 3,4 and 22).
Bed-load Sediment material transported by rolling, sliding and saltation motion along the bed.
Belanger Jean-Baptiste Ch. Belanger (1789-1874) was a French hydraulician and Professor at the Ecole
Nationale Superieure des Ponts-et-Chaussees (Paris). He suggested first the application of the momen
tum principle to hydraulic jump flow (Belanger, 1828). In the same book, he presented the first 'back
water' calculation for open channel flow.
Belanger equation Momentum equation applied across a hydraulic jump in a horizontal channel (named
after J.B.C. Belanger).
Belidor Bertrand Foret de Belidor (1693-1761) was a teacher at the Ecole Nationale des Ponts-et-
Chaussees. His treatise Architecture Hydraulique (Belidor, 1737-1753) was a well-known hydraulic
textbook in Europe during the 18th and 19th centuries.
Bernoulli Daniel Bernoulli (1700-1782) was a Swiss mathematician, physicist and botanist who developed
the Bernoulli equation in his Hydrodynamica, de viribus et motibus fluidorum textbook (first draft in
1733, first publication in 1738, Strasbourg).
Bessel Friedrich Wilhelm Bessel (1784-1846) was a German astronomer and mathematician. In 1810
he computed the orbit of Halley's comet. As a mathematician he introduced the Bessel functions (or cir
cular functions) which have found wide use in physics, engineering and mathematical astronomy.
Bidone Giorgio Bidone (1781-1839) was an Italian hydraulician. His experimental investigations on the
hydraulic jump were published between 1820 and 1826.