Introduction
to Catchment Hydraulics (CIVL3110)Introduction
to Catchment Hydraulics (CIVL3110)Catchment processes: precipitation, evapotranspiration, infiltration & runoff; generation of flows from catchements; statistical analysis of hydrological data; behaviour of flows in channels; open channel flow.
Subject rationale: The term 'Hydraulics' is related to the application of the Fluid Mechanics principles to water engineering structures, civil and environmental engineering facilities: e.g., canal, river, dam, reservoir, water treatment plant.In the subject, the students are introduced to the hydraulics of a catchment : rainfall, runoff and streamflow. The section "Introduction to Open channel flows" applies the basic principles of fluid mechanics to open channel flows. Examples of open channels are natural streams and rivers. Man-made channels include irrigation and navigation canals, drainage ditches, sewer and culvert pipes running partially full, and spillways. The lecture draws upon the students' expertise in catchment hydrology and water runoff gained in Hydrology Part of the subject. The teaching is focused on the application of the fundamental principles to open channel flow and sediment transport. The interactions between hydrology and hydraulics (e.g. rainfall and river discharge) are further discussed and the students are introduced to real-world engineering situations including failures.
The subject is the first of a series of three subjects (CIVL3110, CIVL3120 and CIVL4120) dealing with hydraulic structures and their interactions with the environment.
The subject outline file may be downloaded : Click here (Word format) [Version 1, 12/2/2001].Timetable : Click there (Excel format) [Version 1, 18/2/2001]
+ CHANSON, H. (1999). "The Hydraulics of Open Channel Flows : An Introduction." Butterworth-Heinemann, Oxford, UK, 512 pages (ISBN 0 340 74067 1). {Support website : http://www.bh.com/companions/0340740671} [Bookshop order of book] Corrections & Updates [Newsletters No. 1, No. 2]
Reviews :+ Advanced Hydraulics, CIVL3120 website
{1} Professor P. BATES, University of Bristol. "Changing a winning formula: the hydraulics of open channel flow: an introduction." in Hydrological Processes, Vol. 15, No. 1, Special Issue, 2001, pp. 159-161. {Read Full Review}
"Hubert Chanson's book meet some of the needs for an open channel text in environmental hydraulics. [...] When discussing hydraulics or sediment transport, each section is structured in highly logical manner. Physical properties are discussed initially, followed by a consideration of the basic dynamic equations. In both cases, these descriptions are extremely clear. These sections are also both admirably comprehensive.
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 I can think of no better recommendation than this. This is an excellent book for undergraduate and graduate students in civil engineering interested in open channel flow, and a very useful resource text for those interested in hydraulics outside engineering field."
{2} Professor S.N. LANE, University of Leeds, Environmental Conservation, Volume 27 2000, Issue 3, pp 314-315. {Read Full Review}
"Without a doubt, this is the best introduction to the introduction of 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 flow, I would find it difficult to recommend anything that could improve upon the approach adopted. My overwhelming conclusion is that as an introduction to the hydraulics of open channel flow, it would be impossible to produce a better result. This will appear on both my undergraduate and postgraduate reading lists as the core text. It is rare for me to be so readily persuaded, and Dr Chanson deserves full credit for an outstanding teaching resource."
{3} Professor D.A. ERVINE, Univwersity of Glasgow, Chemical Engineering Research and Design, Trans IChemE, Part A, Vol 78, Number A7, Oct. 2000, pp 1055.{Read Full Review}
"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."
{4} Professor W.H. HAGER, ETH-Zürich (Switz.), Wasser, Energie & Luft, Switzerland, 2000, No. 1/2, p. 55
"The author has succeeded in producing yet another excellent piece of work. [...] All in all, this is a well-written and carefully illustrated book which is useful for all building and environmental engineers. [...] It easily meets highest expectations."
{5}WEBER, L.J. (2001), Jl of Hyd. Engrg., ASCE, Vol. 127, No. 3, pp. 246-247. {Read Full Review}
"The strength of the book is its breadth of coverage. Containing a wealth of information, as well as being appropriate for an advanced undergraduate course on open channel hydraulics, the book delivers a very good cross section of topics. The number of exercises is very impressive and worth the book's cost."
{6} Professor M. JOVANOVIC, University of Belgrade, Urban Water, Vol. 1, No. 3, p. 270. {Read Full Review}
"This book stands apart from similar previously published textbooks in two ways. Firstly, its scope has significantly been extended toward applications. Secondly, by including many exercises,notes, discussions, relevant photographs,and appendices with additional information, it has an original, hand-book-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."
{7} RAJARATNAM, N. (1999), Review for Edward Arnold, University of Alberta, Canada : "This manuscript is well written ans covers : the basics of open channel flows; uniforme and gradually varied flows; sediment transport; physical modelling and has a very good treatment of Hydraulic Structures. It has also numerous interesting historical notes. There also [are a] number of interesting problems."
{8} MONTES, J.S., and HOLLOWAY, D. (1999), Review for Edward Arnold, University of Tasmania, Australia : "[The book] is an Introduction to a very complex subject, and as such we think that it [will] be developed into a very distinct and useful text.[ ...]. It has undeniable unity and character and, with its unusual analysis of historic cases of Hydraulic Design, it [will] provide the student with a very attractive first view of this topic. The book is [....] quite different from the well known textbooks (Ven Te Chow, Henderson and French). It contains some great new material, in the form of a glossary, symbol list, many interesting photos and biographical notes, as well as additional notes that elucidate particular points within each Chapter."
+ Environmental Hydraulics, CIVL4120 website
+ Softwares : HydroChan by Hydrotools software
3. Froude Number
The Froude number is proportional to the square
root of the ratio of the inertial forces over the weight of fluid. The
Froude number is used generally for scaling free surface flows, open
channels
and hydraulic structures. Although the dimensionless number was named
after
William FROUDE, several French researchers used it before. DUPUIT
(1848)
and BRESSE (1860) highlighted the significance of the number to
differentiate
the open channel flow regimes. BAZIN (1865a) confirmed experimentally
the
findings. Ferdinand REECH introduced the dimensionless number for
testing
ships and propellers in 1852. The number is called the Reech-Froude
number
in France (CHANSON
1999, pp. 39-46).
In rectangular channels, the Froude number is
commonly
defined as the ratio of the flow velocity to the square root of the
product
of g times d, where d is the flow depth and g is the gravity
acceleration.
4. Properties of Common Open-Channel Shapes
In practice, natural and man-made channels do not
have often a rectangular cross-section. Critical flow conditions are
defined
as the flow conditions for which the mean specific energy is minimum (CHANSON
1999, pp. 46-48). In a horizontal channel and assuming hydrostatic
pressure distribution, critical flow conditions imply :
Applications of the Momentum Principle : Hydraulic Jump, Surge,
Flow
Resistance in Open Channels
2. Hydraulic jump
A hydraulic jump is a stationary transition from
a rapid (supercritical flow) to a slow flow motion (subcritical flow).
Although the hydraulic jump was described by LEONARDO DA VINCI, the
first
experimental investigations were published by Giorgio BIDONE in 1820.
It
is extremely turbulent and characterised by the development of
large-scale
turbulence, surface waves and spray, energy dissipation and air
entrainment
(eg CHANSON
and BRATTBERG 2000). The large-scale turbulence region is usually
called
the 'roller'. Experimental observations highlight different types of
hydraulic
jumps, depending upon the Froude number of the upstream flow. An
undular
hydraulic jump is observed at low Froude numbers (1< Fr <3):
looking
downstream (Fr=1.2) and sideview (Fr=1.6).
With increasing Froude numbers, other types of jumps include weak jump,
oscillating jump (3.5< Fr <4.5), steady
jump and
strong jump (Fr >10).
These photographs show surfers riding on a hydraulic
jump roller in a river in Munich, Germany (Photo
No. 1 : flow from right to left, Photo
No. 2: looking downstream, Courtesy of Dale YOUNG).
3. Surges and Tidal Bores
A surge in an open channel is a sudden change of
flow depth (i.e. abrupt increase or decrease in depth). An abrupt
increase
in flow depth is called a positive surge while a sudden decrease in
depth
is termed a negative surge. This picture shows an undular
surge (propagation from left to right).
A positive surge looks like a moving hydraulic jump.
The application of the momentum principle to the unsteady flow is based
upon a quasi-steady flow situation analogy (CHANSON
1999, pp. 67-71).
A bore is a positive surge of tidal origin. Tidal
bores occur as the tidal flow turns to rising (e.g. Lynch
1982). Famous ones include the Hangchow (or Hangzhou) bore on the Qiantang
river (photo: (1),
(2) ), the
Amazon bore called pororoca (photo: (1),
(2)
, (3) ;
info:
see below ), the tidal bore on the Seine river (mascaret)
(photo:
(1)
; info: (2) ), the Hoogly (or Hooghly)
bore
on the Gange, the bore on the Mekong river. Smaller tidal bores occur
on
the Severn river near Gloucester, England (photo :
(1),
(2)
, (3) ), on
the
Trent river (aegir) (photo: (1)),
on the Garonne and Dordogne rivers, France (photo: (1),
(2)
; info: (3) ), at Turnagain Arm and Knik Arm,
Cook
Inlet (Alaska) (info:
(1)
; photo: (2) , (3)
), the bores in the Bay of Fundy (New Brunswick, Nova Scotia) like at
Petitcodiac
(info:
(1)
), tidal bores on the Styx river QLD and on the Daly river NT
(Australia),
the tidal bore called benak at Batang Lupar (Malaysia) (photo (1)).
The front of a positive surge absorbs random
disturbances
on both sides of the surge and this makes the positive surge stable and
self-perpetuating. With appropriate boundary conditions, a tidal bore
may
travel long distances upsteam of the river mouth. For example, the
tidal
bore on the Pungue river (Mozambique) is still about 0.7 m high about
50
km upstream of the mouth and it may reach 80 km inland.
Hubert Chanson observed the tidal bore of the
Dordogne
river on 27 Sept. 2000 (5:00pm). The bore propagates first in the
Gironde
before separating and continuing both in the Garonne and in the
Dordogne
(Map).
At St Pardon, the tidal bore was an undular bore on the 27 Sept. 2000.
Photographs No. 1 and 3 illustrate the undular nature of the positive
surge.
Photo
No. 1 shows the arriving bore.
Photo
No. 2 illustrates kayacks and surfers riding the bore.
Photo
No. 3 was taken just downstream of St Pardon while Photo
No. 4 was shot in front of St Pardon.
More pictures of tidal bores are here.More about the tidal bore (mascaret) of the Seine river ...
4. Flow resistance in open channel
flows
In open channel flows, flow resistance can be
neglected
over a short transition as a first approximation, and the
continuity
and Bernoulli equations can be applied to estimate the downstream flow
properties as functions of the upstream flow conditions and boundary
conditions.
But the approximation of frictionless flow is no longer valid for long
channels. Considering a water supply canal extending over several
kilometres,
the bottom and sidewall friction retards the fluid, and, at
equilibrium,
the friction force counterbalances exactly the weight force component
in
the flow direction.
The laws of flow resistance in open channels are
essentially the same as those in closed pipes. In an open channel, the
calculations of the boundary shear stress are complicated
by the existence of the free surface and the wide variety of possible
cross-sectional shapes. The boundary shear stress equals :
to
=
f/8 * r * V2
where f is the Darcy-Weisbach friction factor and V is the mean flow
velocity (HENDERSON 1966, CHANSON
1999).
As for pipe flows, the flow regime in open channels can be either
laminar
or turbulent. In industrial applications, it is commonly accepted that
the flow becomes turbulent for Reynolds numbers larger than 2000 to
3000,
the Reynolds number being defined for pipe and open channel flows as Re
= V*DH/n where DH is
the
hydraulic diameter or equivalent pipe diameter.
The Darcy friction factor f may be calculated as a function of the
relative
roughness ks/DH and Reynolds number from the
Moody
diagram
In open channels, the Darcy-Weisbach friction
equation
(see above) is valid using the hydraulic diameter as equivalent pipe
diameter.
It is the only sound method to estimate the energy loss. For various
reasons
(mainly historical reasons), empirical resistance coefficients (e.g.
Chézy
coefficient) were and are still used. The Chézy coefficient was
introduced in 1768 while the Gauckler-Manning coefficient was first
presented
in 1865 : i.e., well before the classical pipe flow resistance
experiments
in the 1930s. Historically both the Chézy and the
Gauckler-Manning
coefficients were expected to be constant and functions of the
roughness
only. But it is now well recognised that these coefficients are only
constant
for a range of flow rates. Most friction coefficients (except perhaps
the
Darcy friction factor) are estimated 100%-empirically and they apply
only
to fully-rough turbulent water flows (CHANSON
1999).
Note : The Gauckler-Manning equation is often called improperly the
Manning
equation. In fact it was first proposed by the Frenchman P.G. GAUCKLER
in 1867 (GAUCKLER 1867) based upon the re-analysis of experimental data
obtained by H.P.G. DARCY and H. BAZIN (DARCY and BAZIN 1865). Robert
MANNING
(1816-1897), chief-engineer at the Office of Public Works, Ireland,
presented
two flow resitance formula in 1890. One was the 'Gauckler-Manning'
formula
but Robert MANNING did prefer to use his second formula.
Open channel hydraulics - Text book exercises with solutions:
http://www.bh.com/companions/0340740671/exercises/ (or http://www.bh.com/companions/0340740671/exercises/exercisesP1.htm).Tutorial No. 1 : Fluid properties and basic equations. Bernoulli principle (1) (version 8/3/01).
Tutorial No. 2 : Bernoulli principle (2). Momentum principle. Hydraulic jump, surges, flow resistance (version 16/5/01).
Tutorial No. 3 : Uniform equilibrium and gradually-varied flows (version 10/5/01).
Tidal bore on the Dordogne river (27/9/2000)Open channel hydraulicsGeneral information - Experiment description
Two experiments are performed. : a study of a broad-crested weir overflow (photo) and the hydraulic jump (photo). The former (broad-crested weir) is a smooth transition from an upstream sub-critical flow to a downstream supercritical flow. The latter (hydraulic jump) is the transition from an upstream supercritical flow to a downstream subcritical flow.
Rating : [***] = superb, must see - [**] = excellent
Rivers Seen from Space [**]
EPA Multimedia projects (USA) (computations, remote sensing)
Structurae, International Database and Gallery of Structures [**]
Gallery of Photographs in Fluid Mechanics, Hydraulic & Environmental Engineering and Engineering History
Aerial photographs of American rivers and valleys [**]The Formal Water Garden
Unesco World Heritage Listing (for Virtual Tours, click here [**])
Gallery of photographs in fluid dynamics by Mark Kramer [**]
SoftwaresHydrochan (TM) [**] Gradually-varied flows (1D)
US Army Corps of Engineers HEC Softwares
California 1997 Flood Images
Chicago Calumet waterway: sidestream aeration cascades
Petit-saut dam (French Guyana)
US Army Corps of Engineers, Walla Walla district [Photographs are listed Here]
US Army Corps of Engineers, Portland district, Photofile [**]History of arch dams
The Rideau Canal (Canada) incl. the 1831 Jones Falls arch dam [*]
Steel damsTimber Crib Weirs in Queensland, Australia
Air entrainment on chutes spillways
Rubber dams
Minimum Energy Loss (MEL) culverts and bridge waterways
Embankment overflow stepped spillways: earth dam spillways with precast concrete blocks
Spillway Aeration Devices to prevent Cavitation Damage in high-head chutes {http://www.uq.edu.au/~e2hchans/aer_dev.html}
LacusCurtius - Roman Waterworks and Hydraulic Engineering [***]
Roman Aqueducts and Water Systems (Rome aqueduct system)
Ostia - Harbour of Ancient Rome (Italy)
Gorze Aqueduct at Metz (France) [**]
The Aqueduct in Caesarea (Israel)
Aqueduc de Cahors (in French)Hydraulics of Roman Aqueducts : Steep Chutes, Cascades and Dropshafts, AJA, 2000
Dr Lockington's CIVL3110 home page
El Niño Information in California
The tidal bore of the Seine river
Chicago Calumet waterway: sidestream aeration cascades
Petit-saut dam (French Guyana): aeration cascade
Petit-Saut dam : photographs, dam details
Bureau of Meteorology
Goulburn-Murray Water
Hydro-Electric Corporation (Tasmania)
Murray-Darling Basin Commission
NSW Department of Land and Water Conservation
QLD Department of Natural Resources [Water, Storages]
Mount St. Helens (USA), debris and mud flows, Photofile [**]
French Naval and Hydrographic Service SHOM [**]
Tidal bore (mascaret) of the Seine river
Photographs of tidal bores (incl. mascaret, pororoca)Tide calculations worldwide (in French)
Coastal engineering web page of Dr Robert A. Dalrymple
Tsunami : Information - Photographs
University of Queensland LibraryThis page was visited :Measurement systems : SI Units and significant figures
Reprints of Research Papers in Water enginering
ICEnet: The Institution of Civil Engineers Homepage
Japan Society of Civil Engineers
ASCE - American Society of Civil Engineers Homepage
ASME Meetings & Exhibits Frames IndexENPC
Welcome to the IAHR homepageUS Geological Survey
Civil Engineering Resources on the Internet (GuideMe.com)Highlights in the History of Hydraulics by Hunter ROUSE
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Chanson's Home Page
