This document provides an overview of hydrographic surveying. It defines key terms like hydrography, soundings, and horizontal and vertical controls. It describes common equipment used for hydrographic surveys like sounding boats, poles, lead lines, sounding machines, and echo sounders. It explains methods for locating soundings, such as using a cross rope, ranges and time intervals, or ranges with angular observations from shore or boat. The goal of hydrographic surveying is to accurately map bodies of water by taking depth measurements and positioning them spatially.
Hydrographic survey is the survey of physical features present underwater.
This slide briefs you about the definition of the survey, its application, use, etc. It also discusses the sounding process used in the hydrographic survey.
Hydrographic surveying or bathymetric surveying is the survey of physical features present underwater. It is the science of measuring all factors beneath water that affect all the marine activities like dredging, marine constructions, offshore drilling etc.
In this report, I shall discuss the importance and applications of hydrographic surveying, the devices used for the hydrographic survivor, how he uses them, and how do they work.
Hydrographic survey is the survey of physical features present underwater.
This slide briefs you about the definition of the survey, its application, use, etc. It also discusses the sounding process used in the hydrographic survey.
Hydrographic surveying or bathymetric surveying is the survey of physical features present underwater. It is the science of measuring all factors beneath water that affect all the marine activities like dredging, marine constructions, offshore drilling etc.
In this report, I shall discuss the importance and applications of hydrographic surveying, the devices used for the hydrographic survivor, how he uses them, and how do they work.
Definition of Surveying
Objects of Surveying
Uses of Surveying
Primary Divisions of Surveying
Principles of Surveying
List of Classification of Surveying
Definitions : Plan and Map, scales :Plain Scale and Diagonal Scale,
Methods of Shore Observations for Horizontal position FixingNzar Braim
This report is about the methods of observations of the shore for fixing the horizontal
control position, I will try to explain the hydrographic engineering science within its
advantages and applications and the most common methods used in hydrography
briefly.
We knew that the depths of the water bodies at various points and will be changed
and unstable so Depths are determined by making sounding which is determining the
depth of water from the stationary boat and the positions of sounding can be determined
either from the boat from shore or both of them.
If we want to make a survey Project or let's say if a surveyor wants to make a survey
project for hydrographic surveying and observation for this project so he needs
many processes many preparations many techniques many tools equipment and
So For establishing horizontal control and vertical control points, we have many
methods either offshore or onshore or both I mean from a boat or shore or both
consequently, I wrote a report about this important t subject and In this report I
mention all methods and explain the three applicable and using methods that have
been used in hydrographic surveying and also mention which method is good or
better than the other and the advantages and disadvantages of these methods.At the end
my aim for preparing this report is to show the importance of hydrographic surveying
and how these methods can be used and all require and need for these methods and
also mention all steps, all equations that must be used for these methods.
Finally most important point I should mention it is a co-ordinated system or finding the
coordinates .the surveyor deals with the coordinates, so we make all these processes,
learning all methods, equations, formulas, steps, establishing control points, all above
just for one purpose which is finding the or calculating coordinate, and the most
the important thing in coordinate is accuracy, avoiding errors and uncertainty.
2013 PLSC Track, Hydrographic Surveying and GIS by Carlos CaceresGIS in the Rockies
This presentation is to inform the audience about hydrographic surveying done at Denver Water’s reservoirs. In this presentation, I will show how we collect, process, and use the data. I will discuss the software used such as Hypack software, AutoCAD Civil 3D, and most importantly ArcGIS. We are able to map the depths of the reservoirs to determine water volumes that will be used by Water Recourses Analysis Division.
Definition of Surveying
Objects of Surveying
Uses of Surveying
Primary Divisions of Surveying
Principles of Surveying
List of Classification of Surveying
Definitions : Plan and Map, scales :Plain Scale and Diagonal Scale,
Methods of Shore Observations for Horizontal position FixingNzar Braim
This report is about the methods of observations of the shore for fixing the horizontal
control position, I will try to explain the hydrographic engineering science within its
advantages and applications and the most common methods used in hydrography
briefly.
We knew that the depths of the water bodies at various points and will be changed
and unstable so Depths are determined by making sounding which is determining the
depth of water from the stationary boat and the positions of sounding can be determined
either from the boat from shore or both of them.
If we want to make a survey Project or let's say if a surveyor wants to make a survey
project for hydrographic surveying and observation for this project so he needs
many processes many preparations many techniques many tools equipment and
So For establishing horizontal control and vertical control points, we have many
methods either offshore or onshore or both I mean from a boat or shore or both
consequently, I wrote a report about this important t subject and In this report I
mention all methods and explain the three applicable and using methods that have
been used in hydrographic surveying and also mention which method is good or
better than the other and the advantages and disadvantages of these methods.At the end
my aim for preparing this report is to show the importance of hydrographic surveying
and how these methods can be used and all require and need for these methods and
also mention all steps, all equations that must be used for these methods.
Finally most important point I should mention it is a co-ordinated system or finding the
coordinates .the surveyor deals with the coordinates, so we make all these processes,
learning all methods, equations, formulas, steps, establishing control points, all above
just for one purpose which is finding the or calculating coordinate, and the most
the important thing in coordinate is accuracy, avoiding errors and uncertainty.
2013 PLSC Track, Hydrographic Surveying and GIS by Carlos CaceresGIS in the Rockies
This presentation is to inform the audience about hydrographic surveying done at Denver Water’s reservoirs. In this presentation, I will show how we collect, process, and use the data. I will discuss the software used such as Hypack software, AutoCAD Civil 3D, and most importantly ArcGIS. We are able to map the depths of the reservoirs to determine water volumes that will be used by Water Recourses Analysis Division.
It’s hard to get a highly Paid Job without any information & Skills. All the corporate culture needs prior experience. They don’t want to waste their resources to the people who don’t know. SO come to us, Get yourself trained by knowing the history of the field, business structure, your route of finding a place in one of the biggest job producing markets of the world with just a little effort to develop the skills. TSK- Training For skills and knowledge is the best institute in Rawalpindi Islamabad Pakistan for trainings and courses which leads you towards highly paid jobs. For more info visit www.trainingcourses.com.pk
Top 10 hydrographic surveyor interview questions and answersbutlerrhett166
In this file, you can ref interview materials for hydrographic surveyor such as types of interview questions, hydrographic surveyor situational interview, hydrographic surveyor behavioral interview…
By Sander Terwee, Sales Engineer Geometius bv
Remotely operated boats offer convenience for hydrographic surveyors conducting shallow water inshore bathymetric surveys. Oceanscience Z-Boat 1800 offers a “turn key” solution and is particularly suited for fast and convenient volume surveys in industrial water storage ponds, tailing ponds, construction sites or hazardous locations. Instead of mobilizing a manned boat for a small survey area, simply launch the Z- boat and start surveying immediately. A single operator can conduct a survey at a much lower cost than a full survey crew. In addition, safety is maintained by not having personnel on the water.
A log book of Hydrographic Survey presentationsPeter McCready
Applications and Research in Hydrographic Surveying:
Notes from Hydrographic Survey talks provided by various companies and people of various levels of employment within the industry.
Produced in fulfilment of MSc Geospatial & Mapping Sciences at the University of Glasgow (2015).
The energy of sea waves can be absorbed by wave energy converters in a variety of manners, but in every case
the transferred power is highly fluctuating in several time-scales, especially the wave-to-wave or the wave group
time-scales. In most devices developed or considered so far, the final product is electrical energy to be supplied
to a grid. This paper discusses the use of sea wave energy with the help of oscillating column. The mechanism
converts the wave energy in to electrical power by converting the oscillating motion of waves in to rotary
motion. Using compression ring we can store the power produced by the impact. This stored energy can be
utilized in other strokes. The sea, which covers three quarters of the world’s surface, has been little utilized to
meet the peoples’ energy needs.
Hydrographic surveying
It is the branch of surveying which deals with water bodies e.g. Lake, river etc.
The usual fundamental principles of surveying and levelling are adopted for acquiring data for determination of :
Water volume
Rate of flow
To determine the shape of the area underlying the water surface etc.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
C OMPREHENSIVE S TUDY OF A COUSTIC C HANNEL M ODELS FOR U NDERWATER W I...IJCI JOURNAL
In underwater acoustic communication, shallow water
and deep water are two different mediums which
exhibit many challenges to deal with due to the tim
e varying multipath and Doppler Effect in the forme
r
case and multipath propagation in the latter case.
In this paper, the characteristics of the acoustic
propagation are described in detail and channel mod
els based on the various propagation phenomena in
shallow water channel and deep water channel as wel
l are presented and the transmission losses incurre
d
in each model are thoroughly investigated. Signal t
o noise ratio (SNR) at the receiver is thoroughly
analyzed. Numerical results obtained through analyt
ical simulations carried out in MATLAB bring to lig
ht
the important issues to be considered so as to deve
lop suitable communication protocols for Underwater
Wireless Communication Networks (UWCNs) to provide
effective and reliable communication.
Acoustics and vibrations of marine renewables- Mark-Paul Buckinghamrebeccalynam
Xi Engineering Consultants will share their expertise in this field and discuss their latest research on the noise effects of operational offshore wind turbines on marine species that commonly occur in the Irish Sea.
Reservoir Characterization from Abnormal Pressure in Parts of Eleme, Southea...Scientific Review SR
Pressure in Geophysics is mostly explained in terms of hydrostatics. It is a three dimensional stress
state in which the magnitude of stress is the same in all directions. The pressure of a fluid is said to be “abnormal
pressure” if it is greater or lower than normal. Normal pressure is regarded as the rate of increase of formation
density where the pore pressure remains hydrostatic. The determination of zones of abnormal pressure was done
using geophysical well log method in the Eleme area. Sonic log and density log formed the porosity log and
consequently the porosity data. The logs were interpreted and plotted against depth. The trends were analysed for
wells and abnormal pressure. Overpressure was determined in between particular depths. For the two wells used,
it is found between 2185m and 2785m for well A and 1805m to 2525m for well B. Abnornally high pressure
zones have density of formation greater than 1.07kg/cm
3
. They also have pressure gradients exceeding
hydrostatic pressure gradients of 0.433psi/ft to 0.435psi/ft for fresh and brackish water with less than 20000ppm
of salt and 0.465psi/ft for salt water with about 80000ppm salt content. The determined abnormal pressure can be
taken as a guide in the Eleme area of Nigeria when oil wells are to be dr illed
Powerpoint presentation on Hydrographic Surveying..
It's include the all basic information on Hydrographic survey which can be useful in learning and as an imp. points for exam
—Laboratory experiments on local scour process at wing wall bridge abutments were conducted for different hydraulic conditions and compared with measurements on local scour depths around vertical wall abutments, under the same flow and sediment transport conditions. The study reports an extensive experimental investigation performed in a laboratory flume in the Technological Educational Institute of Thessaly, whose findings are used to describe the effects of different hydraulic parameters on local scour depth variation in the vicinity of the constructions. Three different sizes of wing wall abutment's lengths, transverse to the flow direction, were used in order to investigate the impact of this parameter to local scour variation. The expected bed erosion and the maximum scour depth at the upstream edge of the wing wall abutments are satisfactorily simulated by the experimental procedure. All the experimental results are graphically presented and comparisons between clear-water scour depths around the vertical wall and the wing wall abutments show lower values of scour depths in the vicinity of the wing wall abutments, under the same hydraulic and sediment transport conditions and for the same abutment widths. The experimental data of clear-water scour conditions were used to determine an equation of maximum equilibrium scour depth through regression analysis. The estimated scour depths were in agreement with the experimental values for each abutment geometry.
Similar to Hydrographic survey for std not print (20)
1. CHAPTER 3 : HYDROGRAPHIC
SURVEY
Prepared By:
Asst. Prof. Pramesh Hada
MSC in Urban Planning
B.E In Civil
Asst. Professor, Civil Engineering Dept.
Nepal Engineering College
2. CONTENTS
3.1 Introduction, Definition of Basic Terms(pu08)
3.2 Vertical & Horizontal Controls
3.3 Equipment & Methods of
Sounding(pu06,07,09,10,11,14)
3.4 Measurement of Cross-Section
3.5 Measurement of Velocity & Flow (pu07,09)
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
3.5 Measurement of Velocity & Flow (pu07,09)
3.6 Instruction on Field Works
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
3. 3.1 INTRODUCTION, DEFINITION OF BASIC TERMS
HYDROGRAPHY
Branch of science that deals with the
measurement of bodies of water.
Is the branch of applied sciences which
deals with the measurement and
description of the physical features of
oceans, seas, coastal areas, lakes and
rivers, as well as with the prediction of
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
rivers, as well as with the prediction of
their change over time, for the primary
purpose of safety of navigation and in
support of all other marine activities,
including economic development,
security and defence, scientific research,
and environmental protection.
Is a important tool for hydrologic
studies.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
4. HYDROGRAPHY
Hydrographic surveying deals with the configuration
of the bottom and adjacent land areas of oceans,
lakes, rivers, harbors and other water forms on
Earth.
In strict sense, it is defined merely as the surveying
of a water area; however, in modern usage it may
include a wide variety of other objectives.
- such as measurements of tides, current, gravity, earth
magnetism, and determinations of the physical and
ada,Asst.Prof,civil
artment,nec
magnetism, and determinations of the physical and
chemical properties of water.
The principal objective of most hydrographic surveys,
is to obtain basic data for the compilation of nautical
charts with emphasis on the features that may affect safe
navigation.
Other objectives include acquiring the information
necessary for related marine navigational products and
for coastal zone management, engineering, and science
Er.Pramesh
Engineering
5. SIGNIFICANCE OF HYDROGRAPHIC SURVEY
PU 2006,2007,2008
The Purpose of hydrographic survey are as follows:
Used for controlling and planning of engineering projects
like bridge,dams,tunnels,reservoirs,harbours etc.
To determine mean sea level and observation of tides.
For the measurement of discharge of rivers.
For the measurement of areas subjected to scour or silting
ada,Asst.Prof,civil
artment,nec
For the measurement of areas subjected to scour or silting
and to ascertain the quantities of degraded material.
For the determination of shore lines.
For making subsequent investigation to secure information
needed for the construction, development & improvement
of port facilities.
Determination of coastal erosion, silting.
Determination of site of construction of harbours,
dockyards.
Er.Pramesh
Engineering
8. BASIC TERMS
Sounding : A Measurement of depth of water.
Harbour : A place where ships are parked for cargo
& others.
Reef : A submerged ridge of rock near the surface of
the water
M.S.L (Mean Sea level) : Average of Sea level,
Height according to mean sea level
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
Height according to mean sea level
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
12. 3.2 VERTICAL & HORIZONTAL CONTROLS
Vertical control – Depth Calculated (R.l calculated)
Horizontal control – Northing and Easting calculated (X & Y)
The main objective in hydrographic surveying is to determine the
depth of water at a certain point.
Hence Sounding is the measurement of depth below the water
surface.
For Sounding, A vertical control is needed and to locate the
sounding, a horizontal control is needed.
Horizontal control may consist of either a triangulation or a
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
Horizontal control may consist of either a triangulation or a
traverse. Triangulation may have to be employed for horizontal
connection of widely seperated points.
Traverse may be done by chain,tape, plane tabling or by theodolite,
depending upon the stations.
Hence the underwater & near water points may be located with
reference to the traverse or triangulation.
Vertical connection may be affected by the determination of the
depth of the point below the water surface. Such determinations are
known as “Soundings”.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
13. 3.3 EQUIPMENTS NEEDED FOR SOUNDING (IMP)
Sounding Boat
Sounding Poles
Lead lines
Sounding Machine
Eco – Sounding (Fathometer)
Sounding Boat
Used for taking sounding.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
Used for taking sounding.
should be sufficiently spacious and stable.
For quiet water. a flat bottom boat is more suitable, but
for rough water round-bottomed boat is more suitable.
For regular soundings, a row boat may be provided with
a well through which soundings are taken.
Should be extended far enough over the side to prevent
the line from striking the boat.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
15. SOUNDING POLES/RODS
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
Is a pole of a sound straight-grained well
seasoned tough timber usually 5 to 8 cm in
diameter and 5 to 8 metre long.
Suitable for shallow and quiet waters.
An arrow or lead shoe of sufficient weight
is fitted at the end.
Helps in holding them upright in water.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
Helps in holding them upright in water.
lead or weight should be of sufficient area
so that it may not sink in mud or sand.
Pole of 6 m can be used to depths upto 4
metres.
17. LEAD LINES
lead line or a sounding line is usually a length of a
such cord, or a brass chain with a sounding lead
attached to the end.
Due to prolonged use, a line of hemp or cotton is liable
to get stretched.
It should be soaked in water for about one hour before
it is used for taking soundings.
length of the line should be tested frequently with a
tape.
Er.PrameshHada
EngineeringDepartment,nec
tape.
For regular sounding. a chain of brass, steel or iron is
preferred.
usually used for depths over about 6 metres.
Sounding lead is a weight (made of lead) attached
to the line.
weight is conical in shape and varies from 4 to 12 kg
depending upon the depth of water and the strength
of the current.
often has cup-shaped cavity at the bottom.
Hada,Asst.Prof,civil
Department,nec
19. SOUNDING MACHINE
Where much of sounding is to be done, a
sounding machine as very useful.
May either be hand driven or automatic. Fig.
1 shows a typical hand driven Weddele’s
sounding machine.
lead weight is carried at the end of a flexible
wire cord attached to the barrel and can be
lowered at any desired rate, the speed of the
drum being controlled by means of a brake.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
drum being controlled by means of a brake.
Readings are indicated in two dials — the
outer dial showing the depth in feet and the
inner showing tenths of a foot.
Handle is used to raise the level which can be
suspended at any height.
Is mounted in a sounding boat and can be
used up to a maximum depth of 100 ft.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
21. ECO – SOUNDING (FATHOMETER) (V.V.IMP)
Echo sounder is used for measuring depths of
large rivers, in excess of 10 m, and those of
seas.
Eco sounding is a technique of using sound
pulse to find the depth of water.
Is an electrical instrument, in which a sound
impulse from the surface of water is Sent
towards the bottom of the river or sea (Fig.
13.8).
Sound waves are reflected back From the
bed in the form of an echo which is arrested
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
Sound waves are reflected back From the
bed in the form of an echo which is arrested
by the receiver.
There is an automatic recording of the time
of onward and backward travel of the sound
wave.
Taking the velocity of sound in water to be
approximately 1470 m/s, the depth of water
can be computed.
Generally the echo sounder is placed just at
the water level to eliminate transmission loss
and obtain an accurate result.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
22. ECO – SOUNDING (FATHOMETER)
Uses for Ocean sounding where depth is too
much.
It is adjusted to read depth in accordance with
the velocity of sound in the type of water in
which it is being used.
For Eco sounding Instrument called
“Fathometer” is used.
A fathometer may indicate the depth visually
or indicate graphically on a roll which
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
or indicate graphically on a roll which
continuously goes on revolving and provide a
virtual of the lake or sea.
The main parts of echo-sounding apparatus
are :
1. Transmitting and receiving oscillator.
2. Recorder Unit
3. Transmitter/Power unit
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
23. PRINCIPLE OF ECO SOUNDING
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
•Fig Below illustrates, the principle of
echo sounding.
•Consists in recording the interval of
time between the emission of a sound
impulse direct to the bottom of the sea
and the reception of the wave or echo
reflected from the bottom.
•If the speed of sound in that water is V
and time interval between the
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
and time interval between the
transmitter and receiver is t, then the
depth is given by , h = 1/2(Vt)
•Velocity varies with salinity & temp. of
sea water, so accoustic velocity in sea
water is -
S – in terms of per 1000.
24. ADVANTAGES OF ECO SOUNDING
It has the following advantages over the older method of lead
line and rod :
Used when a strong current is running and when the
weather is unsuitable for the soundings to be taken with the
lead line & other methods.
Is more accurate as a truly vertical sounding is obtained.
Under normal water conditions in ports and harbours an
accuracy of 7.5 cm may be obtained.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
accuracy of 7.5 cm may be obtained.
Is more sensitive than the lead line.
Record of the depth is plotted immediately and provides a
continuous record of the bottom as the vessel moves forward.
Speed of sounding and plotting is increased.
Error due to estimation of water level in a choppy
sea(irregular) is reduced owing to the instability of the boat.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
26. METHODS OF LOCATING SOUNDING
Soundings are located with reference to the shore traverse
by observations made
(I) entirely from the boat, (ii) entirely from the shore or (iii)
from both,
The following are the methods of location
1. By cross rope
2. By range and time intervals
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
2. By range and time intervals
3. By range and one angle from the shore
4. By range and one angle from the boat
5. By two angles from the shore
6. By two angles from the boat
7. By one angle from shore and one from boat
8. By Intersecting ranges
9. By tacheometric Observation
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
27. 1. Location by Cross Rope
most accurate method of locating the soundings and may be used for
rivers, narrow lakes and for harbors.
Used to determine the quantity of materials removed by dredging,
the soundings being taken before and after the dredging work is
done. (dredging - Remove with a power shovel, usually from a bottom of a body of
water)
Single wire or rope is stretched across the channel and is marked by
metal tags at appropriate known distance along the wire from a
reference point or zero station on shore.
Er.PrameshHada,A
EngineeringDepartm
Methods of Locating Sounding
reference point or zero station on shore.
The soundings are then taken by a weighted pole.
The position of the pole during a Sounding is given by the
graduated rope or line.
,Asst.Prof,civil
rtment,nec
28. 2) Location by range and time interval :
Method used when the width of channel is small and when
great degree of accuracy is not required.
In this method, boat is kept in range with the two signals on
the shore and is rowed along it at constant speed.
soundings are taken at different time intervals, knowing the
constant speed and the total time elapsed at the instant of
sounding.
Distance of the total point can be known along the range.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
Methods of Locating Sounding
3. By range and one angle from the shore
Boat is ranged in line with the two shore signals and rowed
along the ranges.
Point where sounding is taken is fixed on the range by
observation of the angle from the shore.
As the boat proceeds along the shore, other soundings are
also fixed by the observation of angles from the shore.
contd……..
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
29. Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
•Let “B” is the instrument station, A1-A2 is the
range along which the boat is rowed and α1, α2, α3
etc. are the angles measured at B to points 1, 2, 3
etc.
•This method is very accurate and very convenient
for plotting.
•If the angle at the sounding point is less than 30°,
a new instrument station must be chosen.
By range and one angle from the shore
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
a new instrument station must be chosen.
•After first and last soundings & every tenth
soundings are fixed by angular observations and
intermediate points are fixed by time interval.
30. 4. Location by range and one angle
from the boat
Is similar to the previous one except that the
angular fix is made by angular observation from
the boat.
Boat is kept in range with the two shore signals
and is rowed along it.
At the instant the sounding is taken, the angle
subtended at the point between the range and
some prominent point B on the shore is
measured.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
Methods of Locating Sounding
some prominent point B on the shore is
measured.
This method has the following advantages :
Since all the observations are taken from the boat,
the surveyor has better control over the operations.
Mistakes are reduced since the recorder books the
readings directly.
On important fixes, check may be obtained by
measuring a second angle towards some other signal
on the shore.
To obtain good intersections throughout, different
shore objects may be used for reference to measure
the angles.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
31. 5) Location by two angles from the shore
In this method, a point is fixed independent of the
range by angular observations from two points on
the shore.
Used to locate some isolated points.
Two instruments & two surveyor are required &
instrument is selected with accuracy.
If A & B are two instrument station and ‘d’ is
measured accurately.
Instrument stations A and B are precisely connected
to the ground and their positions on plan are known.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
Methods of Locating Sounding
to the ground and their positions on plan are known.
Surveyor on the boat holds a flag for a few seconds,
and on the fall of the flag the sounding and the
angles are observed Simultaneously.
co-ordinates of the position P of the sounding may be
computed from the relations :
Method has the following advantages
Preliminary work of setting out and erecting range
signals is eliminated..
Suitable for strong current of water due to which it
is difficult to row the boat a1on the range line.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
32. 6. LOCATION BY TWO ANGLES FROM THE BOAT
In this method, the position of the boat can be
located by the solution of the three-point
problem by observing the two angles
subtended at the boat by three suitable shore
objects of known position.
Three-shore points should be well-defined and
clearly visible.
Prominent natural objects such as church
spire, lighthouse, flagstaff, buoys etc. are
selected for this purpose.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
spire, lighthouse, flagstaff, buoys etc. are
selected for this purpose.
Let A, B and C are the shore objects and P is
the position of the boat from which the angles
α and β are measured.
Both the angles should be observed
simultaneously with the help of two sextants,
at the instant the sounding is taken.
The method is used to take the soundings at
isolated points.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
33. 7. Location by one angle from shore and
one from boat
This method is used to locate the isolated
points where soundings are taken.
Let two points A and B are chosen on the
shore, one of the points (say A) is the
instrument station where a theodolite is set
up, and the other (say B) is a shore signal or
any other prominent object.
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EngineeringDepartment,nec
Methods of Locating Sounding
any other prominent object.
Sounding is taken at P, the angle α at A is
measured with a theodolite while the angle β
at the boat is measured with the help of a
sextant.
Knowing distance d between the two points A
and B by ground survey, the position of P can
be located by calculating the two co-ordinates
x and y.
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34. 8. Location by Intersecting Ranges
Method is used when it is required to
determine by periodical sounding at the
same points, the rate at which silting or
scouring is taking place.
This is very essential on the harbors
and reservoirs.
The position of sounding is located by
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EngineeringDepartment,nec
Methods of Locating Sounding
The position of sounding is located by
the intersection of two ranges, thus
completely avoiding the angular
observations.
Suitable signals are erected at the shore.
The boat is rowed along a range
perpendicular to the shore and
soundings are taken at the points in
which inclined ranges intersect the
range.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
35. 9. Location by Tacheometric Observations
Method is very much useful in smooth
waters.
Position of the boat is located by
tachometric observations from the shore
on a staff kept vertically on the boat.
Observing the staff intercepts at the
instant the sounding is taken, the
horizontal distance between the
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EngineeringDepartment,nec
Methods of Locating Sounding
horizontal distance between the
instrument stations and the boat is
calculated by :
Direction of the boat (P) is established by
observing the angle (α) at the instrument
station B with reference to any prominent
object A.
Er.PrameshHada,Asst.Prof,civil
EngineeringDepartment,nec
36. 3.4 MEASUREMENT OF CROSS-SECTION
Case I – When the River is small
Two poles are fixed on both banks of the river & a rope is
stretched between them.
The water width of the river is divided into several
compartments of equal width (say b) and the points are
marked by hanging tags or pendants.
Depth of water corresponding to each pendant is measured
by a sounding rod or sounding cable.
Let the depths of water be d0,d1,d2…..Considering the end
compartments as traing1es and other compartments as
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compartments as traing1es and other compartments as
trapeziums, the area is calculated as follows.
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EngineeringDepartment,nec
37. CASE II – WHEN THE AREA IS LARGE
Two centre line AB is taken perpendicular to
the river.
Two stout pegs T1,T2 are fixed on AB.
Then following procedure is adopted:
1. At station A, a theodolite is set up and the
line is ranged properly. The width of the
river is measured by stadia method.
2. The width is divided into equal parts, and
the widths of these compartments are fixed.
Thus the distances AP1, P1P2, P2P3,... are
fixed.
3. Another theodolite is set up at C, so that
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3. Another theodolite is set up at C, so that
AC is perpendicular to AB. The distance AC
is measured (say it is equal to D).
4. Then the angles ( α1, α2… are calculated,
in the following manner.
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5. The calculated angles α1, α2, ... arc set out from the theodolite at C.
Thus, the line of sight of the theodolite at A and that of the theodolite at C
coincide at the points P1, P2, P3, ... which are the points along the cross
section where soundings are to be taken.
6. The depths of water at these points arc measured by a sounding cable or
echo—sounder mounted on a boat.
7. Then the cross—sectional area of the water section is calculated in the
usual manner.
38. MEASUREMENT OF VELOCITY
Measurement of velocity is an important aspect of many direct
stream flow measurement techniques.
Different methods used for the measurement of velocity:
1. Surface float method
2. Sub-surface float method
3. Velocity rod method
4. Pitot tube method
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EngineeringDepartment,nec
5. Current meter method
1. Surface float method
Surface floats are made of cork. and can easily float on water.
Are generally in the form of 10 cm cubes.
The floats are painted red or white and have a small flag
attached on top [Fig. (a)].
(cork –cap or Outer bark of the cork oak; used for stoppers for bottles etc)
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EngineeringDepartment,nec
39. 1. SURFACE FLOAT METHOD
Velocity is measured in the following way:
(a) At the discharge site, a rope is stretched
between two poles fixed on both banks of
the river and the water section is divide d
into several compartments by hanging tags
from a rope [Fig. 13.9(b)].
b)velocity of each compartment is
measured by the float, which is released
slightly ahead of C/S-1. When the float
just crosses the section, the stop watch is
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just crosses the section, the stop watch is
started. When it just crosses C/S-2, the
stopwatch is closed. The time taken by
the float to cover the ‘run’ (known
distance) is noted, and from this the
velocity is calculated [Fig. I3.9(c)j.
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EngineeringDepartment,nec
40. 2. SUB-SURFACE FLOAT METHOD
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EngineeringDepartment,nec
Sub-surface float is a hollow cylinder which is attached
by a cord to a surface float.
Position of the sub-surface float is adjusted according to
the depth of the river. Generally, it is kept 0.2D meters
above the bottom.
In this case, the measured velocity is equal to the mean
velocity.
The procedure of measurement is the same as that in the
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EngineeringDepartment,nec
The procedure of measurement is the same as that in the
surface float method (Fig. 13.10). Here, D is the depth of
water.
41. 3. VELOCITY ROD METHOD
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EngineeringDepartment,nec
Velocity rod made of hollow metal or wood. Its
diameter is about 2.5 to 5 cm.
Weight provided at the bottom of the rod to keep it
vertical. length of the rod is adjustable.
Rod is generally submerged to the extent of O.6D.
The procedure of measurement is exactly similar to
that in the surface float method (Fig. 13.11).
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Department,nec
that in the surface float method (Fig. 13.11).
42. 4. THE PITOT TUBE
Pitot tube is a glass tube bent at an
angle of 90° at the lower end.
Upper end is open and kept above the
water level. The lower end is in the
form of a nozzle, and is directed
upstream.
Due to the velocity of water, the
water column rises in the right limb
(Fig. 13.12). Let the rise in water
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EngineeringDepartment,nec
(Fig. 13.12). Let the rise in water
level be h. Then applying Bernoulli’s
theorem between points A and B.
Measuring the rise of water column
the velocity can be calculated.
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Department,nec
43. 5. CURRENT METER METHOD
Commonly used for measuring the velocity of water.
It consists of the following components.
(a) A tail which keeps the meter in the direction of
alignment,
(b) A system of conical buckets fitted to a spindle
which rotates due to current,
(c) A counterweight which keeps the meter vertical,
and
(d) A headphone for registering the sound produced
by the spindle at every revolution.
Current meter is lowered to a depth of 0.6 D (DCurrent meter is lowered to a depth of 0.6 D (D
being the depth of water) by a suspension cable.
Conical buckets is kept on the upstream side and
the tail on the downstream side.
Due to the velocity of water, the system of conical
buckets rotates about the spindle and a ‘tick’ sound
is emitted once for every revolution. Thus, a
continuous “tick-tick” sound is heard through the
headphone. The number of revolutions per minute
15 counted with the help of a stopwatch.
velocity can be ascertained from the rating table
(supplied by the manufacturer with the meter). This
velocity gives the mean velocity of flow.
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EngineeringDepartment,nec
45. Different structures like notch,weirs,sluice gates are used for
measuring flow or discharge.
Notch – device used for measuring the rate of flow of liquid
through a small channel or a tank.
Weir – concrete or masonary structure placed in an open channel
over which the flow occurs.
A/c to the shape of the opening, it is classified as:
Rectangular weir or notch
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EngineeringDepartment,nec
3.4 Measurement of Flow
Rectangular weir or notch
Triangular weir or notch
Trapezoidal weir or notch
Broad crested weir
Discharge over a Rectangular weir or notch
Discharge through a Triangular weir or notch
Discharge through a Trapezoidal weir or notch
Discharge through a Broad crested weir
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EngineeringDepartment,nec
49. TUTORIAL 1 – HYDROGRAPHIC SURVEY(IMP PU QUESTIONS)
What is Sounding? Explain two most accurate methods of locating sounding
Position. (7)
What is the significance of underwater mapping in hydrographic survey?
Explain Rectangular weir & V-notch methods to find the volume of water in
the river?(8)
Write the purposes of hydrographic survey & Explain the methods of locating
sounding positions.(9)
Explain the terms i)Sounding ii)Echo-sounding iii)sextant (6)
Explain various methods used in the measurement of flow.(6)
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Explain various methods used in the measurement of flow.(6)
What is Echo sounding? Enlist the advantages of Echo Sounding.(7)
What is Sounding ? Explain any three methods of sounding.(7)
Define hydrographic survey. Write the purpose of hydrographic survey . (8)
How do you find the discharge of a river in Hydrographic survey. Describe at
least two methods.(8)
What is Eco-sounding? How it measures the depth of water bodies?
Discuss. (7)
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Department,nec