Water level sensors repot

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STUDY ON WATER LEVEL SENSORS
Under the guidance of
Dr. Sai Bhaskar Reddy,
Project Co- ordinator,climaAdapt Project,
WALAMTARI, Hyderabad.
SUBMITTED BY,
HAFISA HAMEED
JOMOL T JOSEPH
Water and Land Management Training and Research Institute,
Himayatsagar, Hyderabad - 500030.

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CERTIFICATE
Certified that this project report entitled “STUDY ON WATER LEVEL
SENSORS” is a record of project work done independently by Hafisa Hameed and Jomol T
Joseph under my guidance and supervision and has successfully completed their internship
under ClimaAdapt Project.
30/5/2014 Dr. Sai Bhasker Reddy
Project Coordinator,ClimaAdapt
WALAMTARI, Hyderabad.

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ACKNOWLEDGEMENT
We would like to express our deep sense of gratitude to Dr.Leven K.V Asst.
Professor, Department of Irrigation and Drainage Engineering, K.C.A.E.T., for providing
such an wonderful training opportunity at WALAMTARI. We express our sincere gratitude
to Dr. M. Sivaswami, Dean, K.C.A.E.T, Tavanur for his support during the course of
training.
We thank Dr. Sai Bhasker Reddy for his support, valuable guidance, profound
suggestions, constant backing, prolific encouragement and advice throughout this project
work at WALAMTARI. With deep respect, we sincerely acknowledge, Dr. Yella Reddy, for
providing the necessary information and related data and for the timely help rendered by him.
We express our heartfelt gratitude to Sravanthi, water manager,
WALAMTARI, Pranith, WALAMTARI for providing relevant data and necessary help and
support for field data collection. We offer our hearty thanks to Vanitha ,AE (Irrigation and
CAD Dept.), Ramesh, FTC for their sincere and timely help in getting the necessary
information for the study.
We express our heartfelt thanks to Krishna Reddy for his help extended
towards us in course of this work.
Above all we bow our head before the God Almighty whose blessings
empowered us to complete this work successfully.
HAFISA HAMEED
JOMOL T JOSEPH

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CONTENTS
CHAPTER NO: TITLE PAGE NO:
1 INTRODUCTION 5
2 LITERATURE REVIEW 8
3 SITE SELECTION 10
4 ULTRASONIC SENSORS 15
5 RADAR SENSORS 20
6 MOBILE CANAL CONTROL 25
7 LEVEL DISCHARGE CONVERSION 27
8 DISCUSSION WITH HYDROVISION 29
9 FIELD STUDY 33
10 RESULTS AND DISCUSSIONS 36
11 CONCLUSIONS 42
REFERENCES

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CHAPTER 1
INTRODUCTION
1.1 Level Measurements
Measurement is the estimation of the magnitude of some attribute of an object,such
as its length or weight, relative to a unit of measurement. Measurement usually involves
using a measuring instrument, such as a ruler or scale, which is calibrated to compare the
object to some standard, such as a meter or a kilogram. Measurements are crucial in purposes
such as in science and in engineering. Since accurate measurement is essential in many fields,
and since all measurements are necessarily approximations, a great deal of effort must be
taken to make measurements as accurate as possible.
1.2 Sensor
Sensor or transducers is defined as a device that receives energy from one system
and transmit it to another, like physical variable into signal variable. Broadly defined, the
sensor is a device which capable of being actuated by energising input from one or more
transmission media and in turn generating a related signals to one or more transmission
systems. It provides a usable output in response to specified input measured, which may be
physical or mechanical quantity, property, or conditions. The energy transmitted by these
systems may be electrical, mechanical or acoustical. The nature of electrical output from
the transducers depends on the basic principle involved in the design. The output may be
analog, digital or frequency modulated.

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1.3 Selecting a Sensor
The sensor has to be physically compatible with its intended applications. There
have eights specification that should be considered while selecting a sensor.
1) Operating range: Chosen to maintain range requirements and good resolution.
2) Sensitivity: Chosen to allow sufficient output.
3) Frequency response and resonant frequency: Flat over the entire desired range.
4) Environment compatibility: Temperature range, corrosive fluids, pressure, shocks,
interaction, size and mounting restrictions.
5) Minimum sensitivity: To expected stimulus, other than measured.
6) Accuracy: Repeatability and calibration errors as well as errors expected due to sensitivity
to other stimuli.
7) Usage and ruggedness: Ruggedness, both of mechanical and electrical intensities versus
size and weight.
8) Electrical parameters: Length and type of cable required, signal to noise ratio when
combined with amplifiers, and frequency response limitations.
1.4 Types of Level Measurement Sensors.
Various systems in sensors developments have been introduced to assist in crucial
measurements of level. These sensors are most likely incorporates business obligation though

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there are certain sensors provided for non-business or profitable usage and for the usage in
education purposes. There are many physical and application variables that affect the
selection of the optimal level monitoring solution for industrial and / or commercial
processes. Selection is categorized to contact and non-contact sensor. The selection criteria
include the physical: state (liquid, solid or slurry),temperature, pressure or vacuum,
chemistry, dielectric constant of medium, density or specific gravity of medium, agitation,
acoustical or electrical noise, vibration, mechanical shock, tank or bin size and shape; and the
application constraints: price, accuracy, appearance, response rate, ease of calibration or
programming, physical size and mounting of the instrument, monitoring or control of
continuous or discrete (point) levels. The selection criteria selected in this project is non-
contact point level detection or continuous monitoring of solids and liquids. The sensor types
to assist in this particular criterion are as follows:
i. Capacitance level sensor (also called RF)
ii. Ultrasound
iii. Radar
iv. Mobile Canal Control
v. Electromagnetic sensor

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CHAPTER 2
LITERATURE REVIEW
Agricultural land management practices are compatible with the preservation of
water resources. Hydrological diagnoses are needed in order to choose the alternative land
uses, cultivation practices and/or their spatial arrangements (Pandey et.al;)
The monitoring water level in a river or in a reservoir is important in the
applications related to agriculture, flood prevention, and fishing industry, etc. The schemes
developed for measuring water level can be categorized as four types based on the measuring
features: pressure, supersonic waves, heat, and image( Jaehyoung Yu and Hernsoo Han).
Human supervision is limited for several hours and the accuracy is almost not
perfect. Sensors introduces a better solution in accurate level measurements and automatic
processing of water levels (Muhd Asran Bin Abdullah).
According to Dana Gardner,By the year 2000, 50% of all engineers will
design with sensors, up from 16% who routinely used them at the beginning of the decade.
”
Although pressure sensor is easy to use, it has a limitation that it should be
calibrated and replaced frequently due to possible breakdown by continuous water pressure.
Supersonic wave sensor is free from water pressure since it measures the time of travel of
supersonic wave pulse from emitter to receiver reflected by the water surface (. B. Y. Lee and
B. Y. Park).
Use of image sensor for measuring water level is the most recent approach.
Different from other types of sensors, it can provide the surrounding information around the
sensor as well as the water level so that the measured data can be confirmed. It also has
an advantage that it is unaffected by weather (Kon et.al;)
Commenting on his experience with the radar sensor the Environment
Agency's Rikk Smith says, 'We have been very pleased with this sensor because it was quick

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and easy to install and we have not had to touch it since it was installed over five months
ago.”
Ultrasound echo ranging transducers can be used in either wetted (contact) or
non wetted (non-contact) configurations for continuous measurements of liquid level. An
interesting application of wetted transducers is as depth finders and fish finders for ships and
boats. Non wetted transducers can also be used with bulk materials such as grains and
powders (Jerry C.Whitaker),

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CHAPTER 3
SITE SELECTION
This section contains information on site selection based on NEMS (National
Environmental Monitoring Standards). It primarily covers the site related variables to
consider when selecting a site. Ensure that the stationarity, accuracy and operating
requirements laid out in this standard are met. By selecting the best available site and/or
installing the best available control structure, data quality will be maximised and work
minimised over the period of the record. The following standards can be found at
www.landandwater.co.nz.
3.1 SOURCES OF INFORMATION
The following sources of information should be used to determine the most
appropriate stretch of river or shoreline (site) for deploying a station:
advice (where available) on access, stability and history

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3.2 PRACTICAL CONTROLS
Satisfactory natural controls are often difficult to find because topography,
geology, and the range and frequency of flows. For instance, gorges cut through bedrock
provide better control sites than riverbeds on alluvial plains. Purpose-built artificial controls
can often provide a stable rating for a small stream site. Where practicable, an existing natural
or artificial control can be altered to improve its sensitivity or stability. The means of doing
this will vary according to the site and other factors.
3.2.1 Safety
Hazards (for observers, the public, livestock, and wildlife) related to the
location and the measurement activity shall be identified and mitigated.
3.2.2 Hazard Review
On selection of a final site, a hazard review shall be carried out in accordance
with relevant guidelines or best practise.
3.2.3 Stationarity of record
It is maintained when variability of the parameter being measured is only caused by
the natural processes associated with the parameter, and ceases when variability is caused or
affected by other processes, moving the station, or adjusting the recording zero height of the
station’s reduced level. Without stationarity, a data record cannot be analysed for changes
over time (such as climate change). While the accuracy of collection processes may change, it
is critical that the methods and instruments used to collect water level record remain without
bias over the lifetime of the record.
3.3 LEVEL STATIONS
The following aspects shall be considered when selecting a site on a reservoir or
lake.
3.3.1 Access and Legal Requirements
The following access issues of a site shall be considered:
Site safe access over the full anticipated range to be measured

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the ability to position machinery and materials during construction
. Safe access is required for reading staff gauges and to carry
out flow measurements
A long-term access agreement with any landowners whose land must be crossed to gain
access to the site
3.3.2 Installation
Aspects to be considered shall include, for example:
Public safety and site security
Constructability and durability. (In particular, consider protection from flood or wave
damage.)
needs to be solid.
Permanent benchmarks should be present.
An adequate power supply from solar, mains or other power sources
Adequate communication for telemetry
3.3.3 Stability for site
Where practicable, one or more of the following features that are relatively resistant
to erosion shall be present as a control:
constriction in the channel between non-erodible banks

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Where practicable, the following features shall be avoided:
Control that is likely to be affected by vegetal growth on the beds and banks
shall be avoided, or its effects mitigated by weed control measures. Also a control that is
likely to be affected by human interference shall be avoided.
3.4 DEPLOYMENT
Once a site has been selected, the design and construction of the installation type and
deployment of equipment follows. Planning a station requires consideration of a number of
factors that can affect the quality, availability and long-term usefulness of the data that is
collected.
These factors are:

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Safe and convenient access to recording stations is crucial for data
collection. Where permission shall be obtained for access over and installation of equipment
on land, whether private, local authority, corporate or government owned. It may be useful to
precede construction work with a site survey for the purposes of design. At the least, a station
history form should be filled out for the site as soon as records begin, updated following
changes, and checked during the annual site inspection
All materials used in installations shall be of adequate strength, thickness
and durability for the purpose. Generally:
Timber should be treated against rot to an appropriate specification (or better)
-dip galvanised or stainless steel
Security gates or systems shall be installed for the safety of anyone who
visits the vicinity, and to protect the station from vandalism. And also to protect installations
vulnerable to interference and damage, including deliration from flora and fauna.

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CHAPTER 4
DETAILED STUDY OF DIFFERENT SENSORS - ULTRASONIC
SENSORS
4.1 INTRODUCTION
Ultrasonic level sensors are used for non-contact level sensing of highly
viscous liquids, as well as bulk solids. They are also widely used in water treatment
applications for pump control and open channel flow measurement. The sensors emit high
frequency (20 kHz to 200 kHz) acoustic waves that are reflected back to and detected by the
emitting transducer.
Ultrasonic level sensors are also affected by the changing speed of sound
due to moisture, temperature, and pressures. Correction factors can be applied to the level
measurement to improve the accuracy of measurement. Turbulence, foam, steam, chemical
mists (vapours), and changes in the concentration of the process material also affect the
ultrasonic sensor’s response. Turbulence and foam prevent the sound wave from being
properly reflected to the sensor; steam and chemical mists and vapours distort or absorb the
sound wave; and variations in concentration cause changes in the amount of energy in the
sound wave that is reflected back to the sensor. Wave guides are used to prevent errors
caused by these factors.
Proper mounting of the transducer is required to ensure best response to
reflected sound. Since the ultrasonic transducer is used both for transmitting and receiving the
acoustic energy, it is subject to a period of mechanical vibration known as “ringing”. This
vibration must attenuate (stop) before the echoed signal can be processed. The net result is a
distance from the face of the transducer that is blind and cannot detect an object. It is known
as the “blanking zone”, typically 150mm – 1m, depending on the range of the transducer.
The requirement for electronic signal processing circuitry can be used to
make the ultrasonic sensor an intelligent device. Ultrasonic sensors can be designed to
provide point level control, continuous monitoring or both. Due to the presence of a
microprocessor and relatively low power consumption, there is also capability for serial

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communication from to other computing devices making this a good technique for adjusting
calibration and filtering of the sensor signal, remote wireless monitoring or plant network
communications. The ultrasonic sensor enjoys wide popularity due to the powerful mix of
low price and high functionality.
4.2 PRINCIPLE OF MEASUREMENT
An ultrasonic level transmitter is fixed at the top of a tank half filled with liquid. The
reference level for all measurements is the bottom of the tank. Level to be detected is marked
as “C”, and “B” is the distance of the ultrasonic sensor from the liquid level. Ultrasonic pulse
signals are transmitted from the transmitter, and it is reflected back to the sensor. Travel time
of the ultrasonic pulse from sensor to target and back is calculated. Level “C” can be found
by multiplying half of this time with the speed of sound in air. The measuring unit final result
can be centimetres, feet, inches etc.
Level = Speed of sound in air x Time delay / 2

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Ultrasonic Sensor is the heart of the ultrasonic level Transmitter instrument. This
sensor will translate electrical energy into ultrasound waves. Piezoelectric crystals are used
for this conversion process. Piezoelectric crystals will oscillate at high frequencies when
electric energy is applied to it. The reverse is also true. These piezoelectric crystals will
generate electrical signals on receipt of ultrasound. These sensors are capable of sending
ultrasound to an object and receive the echo developed by the object. The echo is converted
into electrical energy for onward processing by the control circuit.
4.3 PRACTICAL LIMITATIONS
a. Velocity of sound changes due to the variation of air temperature. An integrated
temperature sensor is used to compensate for changes in velocity of sound due to temperature
variations.
b. There are some interference echoes developed by the edges, welded joints etc. This is
taken care by the software of the transmitter and called interference echo suppression.
c. Calibration of the transmitter is crucial. Accuracy of measurement depends on the
accuracy of calibration.

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4.4 FUNCTIONAL BLOCK DIAGRAM OF A TYPICAL ULTRASONIC
LEVEL TRANSMITTER
A micro-controller based Control Circuit monitors all the activities of the
ultrasonic level transmitter. There are two Pulse Transmission Circuits, one for transmitter
pulse and the other one for receiver pulse. The pulse generated by the transmitter pulse is
converted to Ultrasound pulses by the Ultrasonic Sensor (Transmitter) and targeted toward
the object. This ultrasound pulse is reflected back as an echo pulse to the Ultrasonic Sensor
(Receiver). The receiver converts this Ultrasonic pulse to an electrical signal pulse through
the pulse generator. The time elapsed, or the reflection time is measured by the counter. This
elapsed time has relation to the level to be measured. This elapsed time is converted to level
by the Control Circuit. There is a Timing Generator Circuit which is used to synchronize all
functions in the ultrasonic level measurement system.
The level is finally converted to 4-20mA signal. 4mA is 0% level, and 20mA is
the 100% level. This 4-20mA output signal carrying the level data can be transmitted to long
distance to Process Control Instruments.( 4-20mA output signal depends on model. It may
vary according to manufacturers.)

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4.5 ADVANTAGES OF ULTRASONIC SENSORS
Ultrasonic level transmitter has no moving parts, and it can measure level
without making physical contact with the object. This typical characteristic of the transmitter
is useful for measuring levels in tanks with corrosive, boiling and hazardous chemicals. The
accuracy of the reading remains unaffected even after changes in the chemical composition or
the dielectric constant of the materials in the process fluids.
4.6 LIMITATIONS
Ultrasonic level transmitters are the best level measuring devices where the
received echo of the ultrasound is of acceptable quality. It is not so convenient if the tank
depth is high or the echo is absorbed or dispersed. The object should not be sound absorbing
type. It is also unsuitable for tanks with too much smoke or high density moisture.

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CHAPTER 5
DETAILED STUDY OF DIFFERENT SENSORS - RADAR
SENSORS
5.1 INTRODUCTION
Radar technology is mainly put into use for detection of level in continuous level
measurement applications. Radar level transmitters provide non contact type of level
measurement. They make use of EM i.e. electromagnetic waves usually in the microwave X-
band range which is near about 10 GHz. Hence, they can be also known as microwave level
measurement devices
A radar level detector basically includes:
 A transmitter with an inbuilt solid-state oscillator
 A radar antenna
 A receiver along with a signal processor and an operator interface.

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5.2 PRINCPLE OF OPERATION
Working principle of radar sensor is similar to ultrasonic sensors. The operation of all
radar level detectors involves sending microwave beams emitted by a sensor to the surface of
liquid in a tank. The electromagnetic waves after hitting the fluids surface returns back to the
sensor which is mounted at the top of the tank or vessel. The time taken by the signal to
return back i.e. time of flight (TOF) is then determined to measure the level of fluid in the
tank.
5.3 TYPES OF RADAR SENSORS
5.3.1 GUIDED WAVE RADAR
In this method, a cable or rod is employed which act as a wave guide and
directs the microwave from the sensor to the surface of material in the tank and then straight
to its bottom. “The basis for GWR is time-domain reflectometry (TDR), which has been used
for years to locate breaks in long lengths of cable that are underground or in building walls. A

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TDR generator develops more than 200,000 pulses of electromagnetic energy that travel
down the waveguide and back.
The dielectric constant of the process material will cause variation in impedance and reflects
the wave back to the radar. Time taken by the pulses to go down and reflect back is
determined to measure level of the fluid.
In this method, the degradation of the signal in use is very less since
the waveguide offers extremely efficient course for signal travel. Hence, level measurement
in case of materials having very low dielectric constant can be done effectively. Also in this
invasive measurement method, pulses are directed via a guide; hence factors like surface
turbulence, foams, vapors or tank obstructions do not influence the measurement. GWR
method is capable of working with different specific gravities and material coatings.
However, there is always a danger that the probe or rod used as a waveguide may get
impaired by the agitator blade or corrosiveness of the fluid under measurement. A typical
guided wave radar system is shown in the figure below.

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5.3.2 THROUGH AIR RADAR SYSTEM
They usually employ a horn antenna or a rod antenna for sending
microwave beams onto the surface of the liquid being measured. These antennas mounted at
the top of the tank then receive the reflected microwave signal back from the fluid surface. A
timing circuit is incorporated in the systems which measures the time of flight and hence the
distance between the antenna and the fluid level is determined. These systems can pose
measurement problems if the dielectric constant of the fluid being measured is very low.
“The reason is that the amount of reflected energy at microwave (radar) frequencies is
dependent on the dielectric constant.
5.4 ADVANTAGES
Major advantages of radar level detectors include:
 Radar level measurement technique offer extremely accurate and reliable detection of
level in storage tanks and process vessels.
 The performance of radar level transmitters remains unaffected by heavy vapors and
mostly all other physical properties of the fluid under level measurement (except
dielectric constant of the liquid).
5.5 DISADVANTAGES
Radar level measurement systems incorporate following drawbacks:
 Major disadvantage associated with radar level detectors is their high cost.
 Besides, these systems are not capable of detecting level between interfaces.
 Also their pressure ratings are very restricted.
 In case of pulse radar, one usually faces problem in getting accurate measurement results
if the fluid being measured is very near to the radar antenna. Since, in that case the time
taken by the signal to travel between sensor and process material will be very fast i.e. not
adequate for accurate determination of level.

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 These devices work well with light layer of dirt and dust only. In situations where the
layer of dust or foam gets substantial, they cease to detect the fluid level. Therefore, in
dirty applications the radar level detectors gets replaced by ultrasonic level detectors.

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CHAPTER 6
DETAILED STUDY OF DIFFERENT SENSORS- MOBILE
CANAL CONTROL
6.1 INTRODUCTION
A recent innovation called The MobileTracker can be seen as the
next generation of semi-automatic measurement devices. the MobileTracker is made for the
smart-phone and uses the telephone’s camera and special pattern-recognition software. This
technology makes manual data entry of water variables unnecessary With MCC it is possible
to perform accurate measurements and control of irrigation canals by using smartphones.
The procedure for taking measurements is as simple as taking a photo with a smart-phone. It
can thus also be used by less experienced personnel. In exceptional circumstances it could
even be used by farmers in remote areas or students passing a stream on their way to school.
The only requirement is a smart-phone.
6.2 WORKING
The Mobile Tracker works as follows: When a field operator arrives at a
location, they take the smart-phone and start an application that makes contact with the
central database. The application uses the GPS coordinates and angles of the smart phone to
identify the location and store all the relevant data. For water level measurements these
would usually be the reference level, subsidence of the staff gauge and known impairments
of the staff gauge. For flow measurements these are, for example, width of the gate and
calibration coefficient. For ground water measurements it is the level of the top of the
groundwater pipe. With one click on the app, a photo is taken and from the photo water
variables such as water level, flow and groundwater level can be measured. These values are
then sent to a database and saved including information pertaining to location with a time
check, the field operator on duty, GPS coordinates and camera angles. The photo is also sent
and saved with the other information. The advantage of this procedure is that is faster than
manual data and no data errors can be made. Because the photo is saved, it can be referred to
afterwards using the correct photo at the right place and at the right time to verify concerns

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about inaccurate readings or disputes about a presumed situation. The central system can be
managed from FEWS. The Mobile Tracker is also connected to WISKI and Aquarius.
Methods are available for measuring water levels, gate positions/flows and ground water
levels.

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CHAPTER 7
LEVEL TO DISCHARGE CONVERSION
To transform a water level to water discharge, there are four practical ways:
(i) to measure the flow velocity at the same time as water level
(ii) to use some particular hydraulically controlled section
(iii)to use pre-calibrating rating-curves and
(iv) to use the mean empirical Gauckler-Manning-Strickler law ( simply denoted hereinafter
as Manning’s equation.)
The three first ways need additional heavy sensors or equipments and,
long-term studies under flow conditions. In a given cross-section of a channel, the water level
can be converted to water discharge using the widely used Manning equation. The Manning
equation was developed empirically in laboratory channels with optimal draining conditions
and uniform flow and no downstream influences must be assumed to apply the equation.
However due to lack of a better solution, it is assumed that the equation is also valid for non-
uniform reaches that are invariably encountered in natural channels if the energy gradient is
modified to reflect only the losses due to boundary friction .
The instantaneous flow velocity v [m.s−1
] and discharge Q [m3
.s−1
] in a
channel are estimated as follows:
v= 1/n R 2/3
S 1/2
Q= v . A
where S [dimensionless] denotes the slope of the water surface, which can be approximated
by the slope of the channel.
As slope and cross-section shape being temporally stable, it can be both
estimated from topographic ground survey. The hydraulic radius depends on water level
which is measured by the stage recorder. The term n can be estimated by choosing, in the
abundant literature, the most suitable coefficient, according to cross-section characteristics
(dimensions and shape), bed substrate and cover types (vegetation, concrete, plastic, etc.).
Assuming that Manning’s equation is relevant, the uncertainty in discharge estimation comes

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mainly from the uncertainty around n, i.e., possible values for this parameter. Indeed,
vegetation is a primary factor in the increase of the roughness and resistance in channels.
Hence, a maximum value should be used during periods of low flows and high vegetation
density, and minimum values during high flows and low vegetation density. Therefore,
discharge estimation is associated to an envelope curve which corresponds to an upper and a
lower acceptable limits on discharge estimation. Hence, when the water level sensor is
installed at a catchment outlet, discharge could be estimated with a given uncertainty and
several indicators could be derived to characterize catchment hydrological behaviour.

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CHAPTER 8
“CHALLENGES IN OPEN CHANNEL DISCHARGE
MEASUREMENT AND VARIOUS SOLUTIONS USING AREA
VELOCITY METHOD”
(Discussion with representatives of HYDROVISION)
8.1 TYPICAL VELOCITY DISTRIBUTIONS FOR SEVERAL
CHANNEL PROFILES

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8.2 TYPES OF ULTRASONIC MEASUREMENT TECHNOLOGY
8.2.1 CONTINUOUS WAVE DOPPLER
Continuous wave (CW) Doppler is the older and electronically more simple
of the two kinds. As the name implies, CW Doppler involves continuous generation of
ultrasound waves coupled with continuous ultrasound reception. A two crystal transducer
accomplishes this dual function.
The main disadvantage of CW Doppler is its lack of selectivity or depth
discrimination. CW Doppler measurements are a spot velocity measurement. The sensor is
not able to determine at which level the velocity has been detected. Due to this reason the
flow profile cannot be represented.

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8.2.2 DIGITAL PULSED DOPPLER
Pulsed wave (PW) Doppler systems use a transducer that alternates
transmission and reception of ultrasound. One main advantage of pulsed Doppler is its
ability to provide Doppler shift data selectively from a small segment along the ultrasound
beam, referred to as the “sample volume”. The location of the sample volume is operator
controlled.
CLASSIFICATION OF DIGITAL DOPPLER
8.3 WATER LEVEL MEASUREMENT
>Bubbler
>Hydrostatic
>Shaft Encoders
>Ultrasonic

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>Radar
>Optical /Video processing
Nowadays Bubbler and Shaft encoders are not in use. New technologies
using radar and ultrasonic waves are now prominent in market. Both ultra-sonic and radar
sensors have non-contact type models.

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CHAPTER 9
FIELD STUDY
9.1 LOCATION
Mirialaguda DC 4 circle irrigation canal systems were studied.
9.2 OBSERVATIONS
>Major canals can be automated using high precision sensors; installed along various site
identified.
> Some portion of the canals were unlined. Lining activity is carried out in certain places
of Wazeerabad (L5 major).
> Canals were not maintained properly; wastes and rocks were dumped.
> Cross section of the canals were not constant, especially the minor canals.
> Farmers are unaware of sensors and water level automation system.
>Permanent structures over canals were identified. (Annexure 1).
Plate 1: L5 major Wazeerabad

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Plate 2: DROP 1 at L5 major (Q = 0.87 C/s)
Plate 3: PIPE NO.1 (0.27 Km from L5 Major)

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Plate 4: L6 Minor of Wazeerabad Major
Plate 5: Unlined canal with varying cross section

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CHAPTER 10
RESULTS AND DISCUSSION
10.1 SENSOR EVALUATION
SENSORS WATER
LEVEL
ACCURACY POWER
INPUT
COST/UNIT
(Rs)
SERVICE OF
AGENCY
1) CAMPBELL
SCIENTIFIC
1 year warranty
>RADAR RANGING SENSOR 4275-72585
a)CS475-L 50mm-
20m
± 5mm 9.6-16
Vdc
b)CS476-L 50mm-
30m
±3mm 9.6-16
Vdc
c)CS477-L 400mm-
70m
±15mm 9.6- 16
Vdc
>SONIC RANGING SENSOR 2565-55285
SR50A-L 0.5-10m ±1cm 9-18 Vdc
2) VIRTUAL
ELECTRONICS
>DIGITAL WATER LEVEL RECORDER-RADAR
TYPE
30210-60125
DWLR-R 15m-70m ±2mm 12 v
3)
HYDROVISION
>ULTRASONIC LEVEL
SENSOR
2575-50254
SEP3702 25m ±2% 24 Vdc
SHANGHAI
CX-RLM RADAR
WATER LEVEL
SENSOR WITH
ALARM
30 m <0.1% 4216-60230 1Year warranty

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10.2 SENSOR SELECTION
Based on the study on different sensors, radar sensors was found to be
more accurate when compared to ultrasonic because
 In flow measurement of open channels, the flow measurement error of
ultrasonic sensors, due to temperature error, can amount to more than 20 %.
Local authorities and individual companies will calculate their costs based
on this measurement data, so substantial differences can arise in their
accounting.
 Since radar is independent of external weather conditions such as rain, solar
radiation, wind or fog, radar measurement is actually the more suitable
alternative.
 Another consideration is that adjustment and operation of radar instruments
has become very easy.
4) CHEMINS
WATER LEVEL
SENSOR LKZLD-A
30 m <0.1% 24 Vdc
RADAR WATER
LEVEL SENSPOR
HD
30 m 6000-12000
5) SHANGHAI
CX-RLM-081
PULSE RADAR
INFRARED
WATER LEVEL
SENSOR
20m <0.1% 7000-60230
RRF-15 70m ±5mm 60230-18690
VRPWRD51-56 20m ±10mm 48184-12460
VRPWRD35 20m ±3mm 24 Vdc 48184-12460
SHAANXI CHINA-RADAR WATER LEVEL
SENSOR
YK=RLT01 35m ±2mm 6023-72276

38. 38
 The benefits for users include high accuracy, high reliability, ease of use
and low costs. Previously, the price difference between radar and ultrasonic
instrumentation was very high; today, the price of radar is comparable to
that of ultrasonic.
When considering about large scale installation of sensors there will be a
great variation in cost among radar and ultrasonic. Ultrasonic sensors can be used
successfully in places were temperature variation is less. Temperature sensitivity of sensor
depends on the modl and the manufacturers. Usually they operate between -2 to 45 0
C.
Canals Sensors Type Description Average cost
for complete
installation(Rs)
Installation
Major RADAR Non-
contact
Highly accurate but
coastlier
30000- 60500 Stand alone
poles or by
providing
extension
hangings

39. 39
Major ULTRASONIC Non-
contact
Accurate but
depends on
temperature
variation
15670- 35000 Stand alone
poles or by
providing
extension
hangings
Major Digital doppler Contact Measures velocity
also
6000 – 30000 Mounted to
canal sides
Minor Digital doppler Contact Measures velocity
also
6000 – 30000 Mounted to
canal sides
Minor Pressure sensor Contact Based on weight of
water
5000-25000 Submerged in
canals
Minor Staff guages Contact Human recording 1000 Mounted
along canal
sided
10.3 SITE SELECTION
Permanent structures were sensors can be mounted in field were
evaluated (bridges and drops).
STRUCTURES
DISTANCE FROM
WAZERABAD MAJOR
CHILLAPUR BRIDGE 0.910 km
DILVARPUR BRIDGE 4.68 km
DILWAPUR S.L BRIDGE 10.22 km
S.L BRIDGE 13.20km
S.L BRIDGE 14.80 km
DROP CUM S.L BRIDGE 11 16.977 km
DROP CUM S.L BRIDGE 14 18.41 km

40. 40
Sensors can be installed economically either beneath the bridges or on drops. Cost can be
reduced by providing small poles clamped to the upstream side of drops with an extension
across the canal. The data of drop structures of Wazerabad major includes
DROP NO: 1 0.914 Km
DROP NO: 3 8.045 Km
DROP NO: 5 11.529 Km
DROP CUM REGULATOR 8 15.690 Km
DROP NO: 12 17.160 Km
DROP NO: 16 20.589 Km
DROP CUM REGULATOR 23 22.433 Km
DROP NO: 25 23.622 Km
Sensors can be mounted approximately in these positions considering the environmental
conditions and human interferences.
10.4 FIELD CHALLENGES
 Farmers are unaware of sensors and its applications. They should be made
aware about sensors and its uses.
 Non- continuous flow through canal causes periodic removal and
installation of sensors.
 Chance of theft is higher
 Providing human security will increase the cost of level measurement
project.
 Provision of security gates and periodic inspection of sensors are
recommended.

41. 41
10.5 SENSOR SUPPLIERS IN MARKET
There are many sensor suppliers in market. We contacted them and
broachers were collected.
HYDROVISION ram.warriar@hydrovision.de
VIRTUAL ELECTRONICS athul@virtualweb.co.in
CAMBELLSCIENTIFIC Krishna.Kishora@elcometech.com
JAYCEETECH jayceetech@vsnl.net
PROTOCOL INSTRUMENTS Sales@baseelectronics.in
A number of other industries were contacted through online Shoppe (CHEMIN,
SHANGHAI etc. ).

42. 42
CHAPTER 11
CONCLUSIONS
Agricultural land management practices should compatible with the
preservation of water resources. Hydrological diagnoses are needed in order to choose the
alternative land uses, cultivation practices etc. The proposed hydrological strategy for open
channel monitoring is based on the study on different sensors and its limitations. Low cost
and energy consumption optimization of the proposed sensor allows one to multiply it in
space and to transmit data to any places required. Moreover, its design and properties (handy,
easy to install and uninstall, low-cost, etc.) make the proposed sensor mobile and soft, which
allow one to simultaneously monitor level with high resolution.
 Among the various non-contact sensors studied, radar sensors are found to give high
resolution data. Based on economic considerations, ultrasonic sensors stand ahead of
the radar sensors. Budjet of the project place a major role in selection among radar
and ultrasonic sensors in major canal. Since minor canal requires less accuracy than
major canal, contact Doppler can be used.
 Permanent structures like bridges are found to be best suited for sensor installation. It
reduces the cost of long poles and foundations.
 Sensors can also be installed successfully on drops; an extension to be provided
across the channel.
 The present field situation does not allow to left back the sensors in field. Periodic
monitoring and security system should be provided to prevent theft and to ensure
proper working of the monitoring system.
 Based on evaluation of different sensor suppliers, HYDROVISION and CAMPELL
SCIENTIFIC were found to provide wide varieties and compact model of sensors.
They also provide good service facilities.
 Further studies should be conducted to study about sensors and the data processing
systems.

43. 43
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