Produced by Chris Curnow, Wayne Hammond and the Online
Distributed Proofreading Team at http://www.pgdp.net (This
file was produced from images generously made available
by The Internet Archive)
[Transcriber’s Note:
Italic text delimited by underscores, bold text delimited by equal
signs.
Single underscore followed by text enclosed by braces indicates
subscript.
Caret followed by single character or text enclosed by braces text is
superscript text.]
RIVER AND CANAL ENGINEERING
_By the Same Author_
HYDRAULICS WITH WORKING TABLES. Second Edition. 160 illustrations,
xii + 311 pp., 8vo (1911).
=12/-= net.
PUNJAB RIVERS AND WORKS. Second Edition. 47 illustrations, viii +64
pp., folio (1912).
=8/-= net.
IRRIGATION WORKS (in the press). 27 illustrations, vi + 130 pp.,
8vo (1913).
=6/-= net.
THE SUCTION CAUSED BY SHIPS. Explained in Popular Language. 2
plates, 26 pp., 8vo, sewed (1912).
1/- net.
E. & F. N. SPON, LTD., LONDON
RIVER AND CANAL
ENGINEERING
THE CHARACTERISTICS OF OPEN FLOWING
STREAMS, AND THE PRINCIPLES
AND METHODS TO BE FOLLOWED IN
DEALING WITH THEM
BY
E. S. BELLASIS, M.INST.C.E.
RECENTLY SUPERINTENDING ENGINEER IN THE IRRIGATION BRANCH OF
THE PUBLIC WORKS DEPARTMENT OF INDIA
_72 ILLUSTRATIONS_
[Illustration]
London
E. & F. N. SPON, LTD., 57 HAYMARKET, S.W.
New York
SPON & CHAMBERLAIN, 123 LIBERTY STREET
1913
TABLE OF CONTENTS
CHAPTER I
INTRODUCTION
ARTICLE PAGE
1. Preliminary Remarks 1
2. Résumé of the Subject 1
3. Design and Execution of Works 3
4. The Hydraulics of Open Streams 4
CHAPTER II
RAINFALL
1. Rainfall Statistics 6
2. Available Rainfall 9
3. Measurement of Rainfall 13
4. Influence of Forests and Vegetation 14
5. Heavy Falls in Short Periods 15
CHAPTER III
COLLECTION OF INFORMATION CONCERNING STREAMS
1. Preliminary Remarks 18
2. Stream Gauges 19
3. Plan and Sections 21
4. Discharge Observations 21
5. Discharge Curves and Tables 23
6. Small Streams 24
7. Intermittent Streams 25
8. Remarks 26
CHAPTER IV
THE SILTING AND SCOURING ACTION OF STREAMS
1. Preliminary Remarks 27
2. Rolled Material 29
3. Materials carried in Suspension 31
4. Methods of Investigation 33
5. Quantity and Distribution of Silt 35
6. Practical Formulæ and Figures 37
7. Action on the Sides of a Channel 40
8. Action at Bends 42
9. General Tendencies of Streams 45
CHAPTER V
METHODS OF INCREASING OR REDUCING SILTING OR SCOUR
1. Preliminary Remarks 48
2. Increase of Scour or Reduction of Silting 48
3. Production of Silt Deposit 51
4. Arrangements at Bifurcations 53
5. A Canal with Headworks in a River 54
6. Protection of the Bed 58
CHAPTER VI
WORKS FOR THE PROTECTION OF BANKS
1. Preliminary Remarks 60
2. Spurs 61
3. Continuous Lining of the Bank 64
4. Heavy Stone Pitching with Apron 71
CHAPTER VII
DIVERSIONS AND CLOSURES OF STREAMS
1. Diversions 73
2. Closure of a Flowing Stream 75
3. Instances of Closures of Streams 80
CHAPTER VIII
THE TRAINING AND CANALISATION OF RIVERS
1. Preliminary Remarks 84
2. Dredging and Excavating 84
3. Reduction of Width 85
4. Alteration of Depth or Water-Level 88
5. Training and Canalising 89
CHAPTER IX
CANALS AND CONDUITS
1. Banks 92
2. Navigation Canals 93
3. Locks 96
4. Other Artificial Channels 100
CHAPTER X
WEIRS AND SLUICES
1. Preliminary Remarks 102
2. General Design of a Weir 105
3. Weirs on Sandy or Porous Soil 106
4. Various Types of Weirs 111
5. Weirs with Sluices 115
6. Falling Shutters 121
7. Adjustable Weirs 126
8. Remarks on Sluices 128
CHAPTER XI
BRIDGES AND SYPHONS
1. Bridges 132
2. Syphons and Culverts 135
3. Training Works 136
CHAPTER XII
DRAINAGE AND FLOODS
1. Preliminary Remarks 141
2. Small Streams 141
3. Rivers 146
4. Prediction of Floods 150
5. Prevention of Floods 153
6. Lowering the Water-Level 154
7. Flood Embankments 156
CHAPTER XIII
RESERVOIRS AND DAMS
1. Reservoirs 162
2. Capacity of Reservoirs 167
3. Earthen Dams 174
4. Masonry Dams 181
CHAPTER XIV
TIDAL WATERS AND WORKS
1. Tides 190
2. Tidal Rivers 192
3. Works in Tidal Rivers 196
4. Tidal Estuaries 197
5. Works in Tidal Estuaries 198
CHAPTER XV
RIVER BARS
1. Deltaic Rivers 203
2. Other Rivers 205
APPENDIX A. Fallacies in the Hydraulics of Streams 209
” B. Pitching and Bed Protection 212
INDEX 213
PREFACE
The object of this book is to describe the principles and practice
adopted in the Engineering of Open Streams. If the book seems to be
somewhat small for its object, it will, it is hoped, be found that this
is due to care in the arrangement and wording.
Sources of information have been acknowledged in the text, but special
mention may be made of lectures given by Professor Unwin at Coopers
Hill College, of Harcourt’s large work on _Rivers and Canals_, of the
papers[1] by Binnie on rainfall, by Shaw on the closing of the river
Tista, by Harcourt on movable weirs and on estuaries, by Strange on
reservoirs, and by Ottley and Brightmore, Gore and Wilson, and Hill
on the stresses in masonry dams; of the articles by Bligh[2] on weirs
with porous foundations and by Deacon[3] on reservoir capacity, of
the Indian Government paper by Spring on “River Control on the Guide
Bank System,” and of the Punjab Government paper containing Kennedy’s
remarks on silting and scour in the Sirhind Canal. The two papers last
mentioned are not easily accessible, and they contain matter of great
interest. The important points, often obscured by masses of detail or
figures, have been extracted.[4]
Silting and scour (CHAP. IV.) had already been dealt with in
_Hydraulics_,[5] but some further information has since come to light
and the subject has been treated afresh and the matter re-written.
E. S. B.
CHELTENHAM, _1st May 1913_.
RIVER AND CANAL ENGINEERING
CHAPTER I
INTRODUCTION
1. =Preliminary Remarks.=--River and Canal Engineering is that branch
of engineering science which deals with the characteristics of streams
flowing in open channels, and with the principles and methods which
should be followed in dealing with, altering, and controlling them.
It is not necessary to make a general distinction between natural and
artificial streams; some irrigation canals or other artificial channels
are as large as rivers and have many of the same characteristics. Any
special remarks applicable to either class will be given as occasion
requires.
2. =Résumé of the Subject.=--CHAP. II. of this book deals with the
collection of information concerning streams, a procedure which is
necessary before any considerable work in connection with a stream can
be undertaken, and often before it can even be decided whether or not
it is to be undertaken. CHAP. III. deals with rainfall, and describes
how rainfall figures and statistics can be utilised by the engineer in
dealing with streams.
CHAP. IV. explains the laws of silting and scouring action, a subject
of great importance and one to which the attention ordinarily given
is insufficient. The general characteristics of streams, being due
entirely to silting or scouring tendencies, are included in this
chapter. CHAP. V. describes how silting or scouring may be, under some
circumstances, artificially induced or retarded.
CHAP. VI. deals with various methods of protecting banks against
erosion or damage. CHAP. VII. treats of diversions or the opening
out of new channels, and with the opposite of this, viz. the closing
of channels, a feat which, when the stream is flowing, is sometimes
very difficult to achieve. This chapter also deals with dredging and
excavation.
CHAP. VIII. discusses the subject of the training of streams, a class
of work which is generally undertaken in order to make them navigable
or to improve their existing capacities for navigation, but may be
undertaken for other reasons. The main features of this kind of work
are the narrowing and deepening of the stream, often the reduction of
the velocity and slope, and generally the raising of the water-level.
In this kind of work a channel may be completely remodelled and even
new reaches constructed. CHAP. IX. deals with artificial channels of
earth or masonry, and includes navigation canals.[6]
In CHAPS. X. and XI. the chief masonry works or isolated structures--as
distinguished from general works which extend over considerable
lengths of channel--are dealt with, and those principles of design
discussed which affect the works in their hydraulic capacities. General
principles of design applicable to all kinds of works, such as the
thicknesses of arches or retaining walls, are not considered; they can
be found in books on general engineering design.
CHAP. XII. treats of storm waters and river floods, and shows how works
can be designed for getting rid of flood water and how floods can be
mitigated or prevented, one of the chief measures, the widening of the
channel and the lowering of the water-level, being the opposite of that
adopted for training works. Embankments for stopping flooding are also
dealt with. CHAP. XIII. deals with reservoirs, including the design of
earthen and masonry dams.
CHAPS. XIV. and XV. deal with tidal waters, river mouths and estuaries,
and works in connection with them, viz. the training of estuaries and
the methods of dealing with bars, the object being in all cases the
improvement of the navigable capacities of the channels.
3. =Design and Execution of Works.=--After obtaining full information
concerning the stream to be dealt with, careful calculations are,
in the case of any large and important work, made as to the effects
which will be produced by it. These effects cannot always be exactly
foreseen. Sometimes matters can be arranged so that the work can be
stopped short at some stage without destroying the utility of the
portion done, or so that the completed work can be altered to some
extent.
In works for controlling streams there is, as will appear in due
course, a considerable choice of types of work and methods of
construction. In practice it will generally be found that there are,
in any particular locality, reasons for giving preference to one
particular type or kind of work or, at all events, that the choice is
limited to a few of them, either because certain kinds of materials
and appliances can be obtained more cheaply and readily than others,
or because works of a particular type have already been successfully
adopted there, or because the people of the district are accustomed to
certain classes of work or methods of construction. In out-of-the-way
places it is often undesirable to avoid any type of work which cannot
be quickly repaired or readily kept in order by such means as exist
near the spot.
It is sometimes said that perishable materials, such as trees,
stakes, and brushwood, cannot produce permanent results. They can
produce results which will last for a long time and which may even be
permanent. By the time the materials have decayed, the changes wrought
may have been very great, deposits of shingle or silt may have occurred
and become covered with vegetation, and there may be little tendency
for matters to revert to their former condition. If the expense of
using more lasting materials had had to be incurred, the works might
never have been carried out at all. On the Mississippi enormous
quantities of work have been done with fascines.
4. =The Hydraulics of Open Streams.=--When any reach of a stream
is altered, say by widening, narrowing, or deepening, so that the
water-level is changed, there will also be a change in the water-level,
a gradually diminishing change, for some distance upstream of the
reach. Also in the lowest portion of the reach the change will
gradually diminish and it will vanish at the extreme downstream end
of the reach. In the next lowest reach there is no change. Thus if it
is desired that the change in the water-level shall take full effect
throughout the whole of a reach, the change in the channel must be
carried further down. If a weir is built there is no change in the
water-level downstream of it except such as may be due to loss of
water in the reach upstream of it. The above points are mentioned here
because, although they are really questions of hydraulics, they are of
much importance and of very general application.
Matters connected with the hydraulics of open streams seem to lend
themselves in a peculiar way to loosely expressed remarks and
fallacious opinions. The set of a stream towards a bank is sometimes
supposed to profoundly affect the discharge of a diversion or branch.
Its effect is simply that of “velocity of approach,” which, as is
well known, is quite small with ordinary velocities, and is merely
equivalent to a very small increase of head. Narrow bridges or other
works are sometimes said to seriously “obstruct” a stream without any
observations being made of the fall in the water surface through the
bridge. This fall is the only measure of the real obstruction.[7]