Hc3113741382

Inyiama, Obota / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 3, Issue 1, January -February 2013, pp.1374-1382
Designing Flood Control Systems Using Wireless Sensor
Networks
Inyiama H. C., Obota M. E.
*Dept Of Electronic And Computer Engineering Nnadi Azikiwe University, Awka, Anambra State, Nigeria
**Dept Of Electronic And Computer Engineering Nnadi Azikiwe University, Awka, Anambra State, Nigeria

Abstract
Recent advancement in information and Nigeria, the incident of flood disaster is becoming
communication technology (ICT) and wireless increasingly worrisome; hence the menace cannot
sensor networks have made new trends to emerge be left unchecked. Although, in recent years, risk-
in flood control practice. Proper prevention and based approaches and other measures have
management of flood is more needed now for continued to receive increasing attention as means to
sustainable socio-economic conditions of the manage flood hazards but all have not yielded the
people. The paper presents an automated flood desired results. It is strongly believed that this
control system based on supervisory control, project when fully implemented would go a long
wired and wireless communication. Efficient way in preventing incessant flood hazards in Nigeria
monitoring and control of water level which and the world at large.
however represents an important input on flood
prevention and control is realised. This Basic Control Concepts
technology, if wisely deployed, could prevent or A control system is a device or system that
reduce the incessant flooding and its attendant maintains or alters the operation of a process. The
hazards on the populace. The benefit of this whole system consists of: (i) the process being
design can be extended to other control systems controlled; (ii) the sensing system (to measure the
e.g. irrigation control, oil spillage control etc. process response if feedback is required); and (iii)
the controller (which incorporates both the software
KEY WORDS: Flood, Control, Sensor, System, and hardware required to control the process).
Controller. Control systems may be either open-loop or closed-
loop: an open-loop control system uses known
INTRODUCTION relationships between the process input and output
According to “oxford dictionary”, “flood” to adjust the controller parameters, while a closed-
is a large quantity of water covering an area that is loop control system measures the output of the
usually dry. Flood may occur as a result of: a heavy process and adjusts the controller parameters to
rainfall, a river flowed over its banks, a burst of minimise the `error signal' which is the difference
water pipes, etc. Flood hazards are the most between the input and the measured output.
common and destructive of all natural disasters. However, difference between these is that closed
Each year, flood disasters cause tremendous loss of loop control systems have feedback from sensors,
lives and property, thereby causing devastating make decisions and apply decisions to the system.
impact on the socio-economic conditions of the On the other hand, open loop control systems apply
people. At least 25 million people living in coastal a preset action, as is done with timers. Since the
regions of Nigeria are at risk of the devastation of controller is the brain behind control system, the
floods before the end of the year [NEMA report]. type of controller used determines control system
The coastal areas of Lagos, Ondo, Delta, Rivers, [1].
Akwa Ibom and Cross River states have already
experienced severe flooding impact since the Open Loop Control Systems
beginning of this year, due to factors such as Open loop control systems use duration or
absence of surface drains and blockage of existing applied volume for control purpose. In this type of
drains, refuse and eroded soil sediment; the plateau controller, the basic control parameters are how
experience of July being the worst in the recent often and how long is the water to be pumped. This
months. Frankly speaking, a flood can devastate type of system is based on a pre-defined control
homes, commercial buildings, agricultural and concept, with no feedback from the controlled
pastoral lands, public goods and other physical object. The user sets the time to start, the time to end
properties. Health sector is not exempted because and the time for pause intervals and the water
there are always threats to health and safety during pumping periods. These parameters are pre-set for
the flood and aftermath. Floodwaters contain disease the entire session as thus:
causing bacteria, dirty oil, human and animal waste  How long the pumping session should
[Public Health Laboratory Service 2000]. In last

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 How often the pumping period should t o t h e m ea sur em en t s pr ovi ded by t h e
repeat itself. sen sor s and th e pr e - pr ogra mm ed
No checking is done to know whether pa ra m et er s, th e c on tr ol l er dec i des on
water is pumped out or not. Open loop control wh en a n d h ow fa r t o e va cua t e t h e wa t er .
system is said to be time-driven. Open l oop Cl os ed l oop c on t r ol l er s ba se t h ei r
c on tr ol s yst em s h a ve t h e a dva n ta ges t ha t deci si on s on :
t h ey a r e l ow c ost , r ea di l y a va i l a bl e, a n d  Mon i t or in g th e st a t e var i a bl es
m an y va r i at i on s of t h e d e vi c es a r e  Com pa r in g th e st a t e va r i a bl es wi t h th e
m an ufa ct ur ed wi t h di ffer en t degr ees of desi r ed va r i a bl es or t a r get sta t e.
fl exi bi l i t y r el a t ed t o t h e n um ber of  De ci di n g wh a t a ct i on s ar e n ecessa r y
st a t i on s a n d sch edul e spe ci fi ca t i on . This t o ch a n ge th e st at e of t h e s yst em .
type of control system, though relatively simple and  Ca rr yi n g out t h e n ecessa r y a ct i on s. A
cheap but in most cases does not provide the optimal cl osed l oop c on t r ol s yst em i s e ven t -
solution to the problem. Howe ver , i t does n ot dr i ven an d h en ce r esp on ds
r espon d a ut om a t i ca l l y to pr eva i l i n g a ut om a t i ca l l y t o pr e va i l i n g ch an ges
ch an ges a n d r equir e fr equen t r eset t i n g t o t h er eby a ch i evi n g h i gh l evel of
a ch i eve h i gh l evel s of e ffi ci en c y [2]. e ffi ci en c y [3].

Cl ose L oop C ontr ol Syste m MATERIALS AND METHODS
T h ese a r e ba sed on a com bi n a t i on of Components requirement: sensor probes
pr e-defi n ed c on t r ol c on cept ( fe ed - (water-level sensors), wireless sensor network (wsn)
for wa r d) a n d fe ed ba ck fr om t h e con t r ol l ed node, poles, controller, water pump for evacuating
obje ct . In th i s t ype of c on t r ol l er , th er e i s water, water channels, software component,
a feed ba ck of t h e n ec e ssa r y da t a t o supervisory component (i.e. SCADA). Generally,
det er m in e wh en t o e va cua t e wa t er . Th e the project is realised in units or modules as thus:
c on tr ol l er r ecei ve s fe ed ba ck fr om on e or water level sensor unit, wireless sensor network
m or e s en sor s in the fi el d that node unit, control unit, actuator unit, and
c on t in uousl y pr ovi de upda t ed da t a t o th e supervisory unit. Fig1 shows the schematic diagram
c on tr ol l er a bou t t h e pa r am et er s t ha t of the automated system.
i n fl uen ce t h e s yst em beh a vi or . Acc or di n g

Water level sensor:
Poles are mounted at various strategic points in the area prone to flooding. The number of poles to be used
depends on the size of the area. A sensor probe is fixed on each pole. The dept in which the probe is hung

on the pole is categorised into two levels {i.e. level 1 and level 2}. Some set of probes are located at lower level,
level1, while other probes are located at the higher level, level 2. The connection between the sensors and the

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wireless sensor network (wsn) node is made by The wireless sensor network node is located at the
coaxial cable. The water level sensor probes are the higher ground outside the flood-prone area. Each
slave sensors while the wireless sensor network wireless device also known as NODE has one or
node is regarded as the master sensor. more sensors integrated in it. Fig 2 shows wsn node
Wireless sensor network (wsn) node: architecture.

Fig 2 wsn node architecture

In addition to sensors, a node is also equipped with to an encoder that carry a unique ID which in turn
transceiver (transmitter and receiver), actuators, will feed its output to a wireless transmitter that
analogue-to-digital and/or digital-to-analogue will transmit the ID of the transmitter and the data
converters, microcomputer and battery. The sensors that indicate the need for flood to be evacuated.
cooperatively continuously monitor water level The node is powered by a 5 V, 1000mAh NiCd
data (water level signal coming from water-level battery. The nodes are programmed to remain most
sensor probe). The actuator provides the control of the time in a sleep mode and wake up only when
function desired (i.e. a switch that turns a motor on the water level goes above the preset value and
or off). The transceiver (transmitter and receiver), then communication with the central controller
is used for wireless communication with other (base station) occurs.
nodes or directly with gateway. The transceiver
modulates and transmits, receives and demodulates Base station (Control unit):
digital data. The gateway in the transceiver is The control logic of the project is
responsible for transmitting sensor data from sensor implemented in the controller, which also has the
patch to remote base station (the central controller). function of integrating all elements of the system.
The microcontroller reads the sensor data and, after Normally, the type of acquisition system is chosen
processing and formatting, outputs the data to the to be optimal for the control algorithm to be used.
wireless transceiver. The microcontroller is also The choice of programming language used in the
responsible for any control command directed to controller is Assembly language. However, any
the actuator. A resistive wireless sensor network other language could be used depending on the
node is designed and built to fit of a wooden plate designer’s choice since the controller used,
measuring 5cm wide and 10cm long. This piece is At89c51 is in the family of 8051. Fi g 3 i s t h e
attached to the technology circuitry, sealed inside a pr oce ss fl owch ar t sh owi n g con t r ol
plastic case with the antenna installed at its top. a l gor i thm . Th e pseud o c ode i s a s fol l ows :
The antenna is a dBi gain double dipole. The sensor i. i ni t i al i z e th e syst em
node circuit board consists of the sensor interface ii. ch eck t h e wa t er l evel
and signal conditioning circuits. The sensor is i i i . ch eck th e com m un i ca t i on syst em
driven by a 200 KHz square wave. The frequency i v. r ea d th e wa t er l evel va l ue
will be changed according to the water level sensor v. com pa r e wa t er l evel wi t h l ower
signal value and the DC output of the filter will limit
indicate the water level. The water level will be vi . s wi t ch on t h e pum p i f gr ea t er or
between 2 and 3.5 V indicating 0-100% water level equa l
in accordance to scale chosen. The output of the vi i . c om pa r e t h e wa t er l e vel wi t h upper
filter is fed to a comparator whose output will be limit
active only when the measured water level is less vi i i . s wi t ch on th e a l ar m i f gr ea t er or
that the pre-set value. The output of the comparator equa l
will activate a low frequency generator circuit that
produces a square wave of 0.1 Hz. This will be fed

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Start

Water level
(WL)

N
Communication ok Motor drives
ok disable

Y

WL < Lower Limit
N < = WL < N WL= >
Lower Upper Limit Upper N
Limit limit

Y Y
Y

Motor Motor Alarm
drive drive Manual
action
disable full v/f required

Fig 3 Controller flowchart

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This controller uses event-based data sampling communication with the supervisor fails, the
technique as against the time-based ones. The controller starts to operate in stand-alone mode,
commonest controller used is a gain scheduling PI with a subroutine based on default parameters. The
scheme where the controller parameters are mode of communication between the controller and
changed based on some disturbances. Controller the supervisory system is wireless and is done by a
receives information from the sensors and sends the GSM Modem in DNP3 protocol. Fig 4 shows
commands to the drives of the pumps. Supervision schematic diagram of communication system.
is established through the SCADA, which can
monitor the situation of the controlled object. If the

SCADA USER

PNEUMATIC
GSM SYSTEM
N/W

PC
INTERFACED SENSOR
WITH GSM INPUT PORT
MODEM
CONTROLLER
Fig 4 Schematic diagram of the communication system

The choice of these standards is justified by the large number of modules for serial communication
consolidated use of GSM/DNP3 applications in ports.
power systems, such as operation of switches and
remote controlled substations. Pumps and Drives
The DNP3 protocol has time stamped variants of A water pump is used to evacuate water
all data so that even with communication failure from the flooded area to a sectioned area via a
between the controller and SCADA, it is still channel. The pumps are normally at low-speed and
possible to recover data to correctly reconstruct the therefore should be coupled to motors by pulleys
sequence of events after the communication is and belts for higher efficiency. Fig 5 shows
restored. A particular feature of this controller, pneumatic diagram of the system.
which is important to this specific application, is a

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120V, 60HZ

STEPDOWN TRANSFORMER 5:1

24V, 60HZ
OUTPUT CONTROLLER
CONNECTED IN
PARALLEL TO 5V SIGNAL TO
POWER THE OPEN THE
RELAY 1
PNUMATIC
SYSTEM
5V SIGNAL
TO OPEN THE
RELAY 2

F. INVERTER
S.S. RELAY 1 S.S RELAY 2

DRVE 2
DRVE 1

PUMP 2
PUMP 1

Fig 5 Pneumatic diagram of the system

The speed of the pumps is controlled by frequency During the maintaining of the water level, the
inverters. It receives the command from the frequency of the drives is adjusted according to the
controller through 5V, 4-20mA channels. The difference between the reference value of water
irrigation pump system uses three-phase AC power level and the value measured by the sensors. A
supply. Due to supply constraints at the some hysteresis loop based on limits of water level is
certain sites, the inverters also have the capability established to prevent the pumps from switching on
of converting the single phase local grid to three- or off at undue situation. Above the lower limit, the
phase. It adopts three-phase solid state relay (SSR) drives are fully activated, according to the rated
SSR-24V, 5A to the controller. Singlechip is values of V and f to evacuate water from the
connected to the SSR. When system receives flood flooded zone. The upper limit of water level is used
evacuation command, control signal will be low to trigger an alarm that requires manual
and open SSR to power the pump to evacuate water intervention to open up sections of the field,
out of the flood area. When the system receives a because the action can no longer be controlled
stop command, control signal becomes high and the automatically.
system stops pumping.

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GSM Modem Medium or High. These levels can be used for
The wireless telemetry unit, model G24 filtering and sorting messages.
(Motorola / Itech) is used to establish
communication between the controller and OPERATION OF THE SYSTEM
supervisory system. This model has the ability to When the water level in the field begins to
automatically manage the GSM connection and rise, a time may reach when it touches two or more
perform the compatibility of this technology to the probes at the lower level. The affected probes are
DPN3 protocol transparently (without protocol now bridged. The bridged probes now send signals
conversion) with the supervisory system used. to the base station (central controller) via wsn node.
Fig 6 shows the architectural diagram of the entire
Supervisory Control and Data Acquisition project. The control logic is implemented in the
(SCADA) base station by articulating and integrating all
The SCADA software allows monitoring elements of the system based on the pre-set
of the controlled object, flood. It also provides a parameters, controlled object and the deployed
friendly interface for the user and allows access to programme. The controller however sends
parameters and control variables of the flood command to the drives of the pump. The water
especially at a critical situation e.g. flood rising to pumps will continue to evacuate water from the
bridge sensor probes of level 2. This critical field in as much as the water level has not dropped
situation can be addressed through the capability of below the lower limit. In a case where the rate of
the alarm screen of the developed system. An water rising outweighs the volume of water being
important SCADA feature is the alarm evacuated, the flood may get to the upper limit
management. It has an application which contains sensors. The signals sent due to the bridge of the
all information on all warning conditions. For each probes at this level triggers alarm which is
source of alarm it is possible to set limits, the accompanied by colour change to be seen from the
message on the event occurrence, its priority and SCADA by the user. The alarm signifies that the
the acknowledgment requisition. The priority flood has gone beyond the control of the system
indicates how important the occurred alarm is. It and hence needs immediate external support or
may assume one of the following levels: Low, intervention before flood hazards occur.

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GSM
MODEM

SCADA
120V,
60HZ
SERIAL PORT CONNECTING PC UNIT
AND CONTROLLER

STEPDOWN TRANSFORMER

24, 60HZ PC
CONTROLLER
OUTPUT
CONNECTED IN 5V SIGNAL TO
PARALLEL TO OPEN THE 10 BIT ADC ON
RELAY 1
POWER THE CONTROLLER
PNUMATIC
SYSTEM 5V SIGNAL
TO OPEN THE
RELAY 2

1O BIT ADC
S.S. RELAY 1 S.S RELAY 2
F. INVERTER SIGNAL
AMPLIFIE
D FROM 0-
1.15V TO 0-
AMP
DRVE 2 5V
DRVE 1

SENSOR
PUMP 2
OUTPUT ANALOG
PUMP 1 OUTPUT
0-1.15V

Fig 6 Architectural diagram of the entire project

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CONCLUSION (10) THOMAS L..D., (2005). Electronic
The work presented in this paper has fundamentals Circuits, Devices and
demonstrated ability to automatically control flood Applications, Prentice-Hall International
based on the water level using water level sensor INC fourth edition
probe and wireless sensor network (WSN). The (11) Peatman, J., (1988). Design with
system technique has provided more supervision Microcontrollers, McGraw-Hill, New
and control than in traditional method of flood York,
control. Available equipment especially water level (12) Horowitz, P., (1996) “The Art
monitoring devices provided needed information to Programming” Cambridge University
the control system. The developed system gives a press,
framework for further research on the quality of (13) Microchip Technology Inc.,(2001).
flood control through the intersection of historical www.microchip.com.
water level data and whether data. The control
system has met all the desired objectives.

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