WATER SUPPLY REMOTE MONITORING SYSTEM:

A CASE STUDY

Henrique Proença, Fernando Ribeiro, José Carlos Metrôlho

Departamento de Engenharia Informática – Escola Superior de Tecnologia de Castelo Branco,

Av. Do Empresário,6000-767Castelo Branco, Portugal

Ricardo Oliveira

Matsushita Electric Works

Av. Adelino Amaro da Costa, nº 728, R/C J - 2750-277 CASCAIS

Keywords: Remote Monitoring, water supply, GSM, Programmable Logic Controller

Abstract: In recent years, there has been enormous research interest in natural resources monitoring. So, there is a

need to develop easily accessible, cheap and reliable information systems for monitoring and early warning,

which could be used in most natural resources. This paper presents an ongoing information system

development that aims at the monitoring and supervising of some parameters on water supply, such as

quality and quantity. To implement our system we use several technologies in order to monitoring about 100

water tanks in an area of ±1000 Km

. Included in these technologies are GSM communication, web

infrastructure and sensing equipment that allows the access of information from any part of the world. In

paper sections the main blocks of the system architecture are described in detail.

1 INTRODUCTION

Water quality is an important indicator of our quality

of life. Is important to guarantee that water never

lacks or loses quality. Monitoring and controlling

levels of some contaminants in drinking water are

important steps towards preventing human health

problems. Even though drinking water, including

bottled water, may reasonably be expected to

contain at least small amounts of some contaminants

this does not necessarily indicate that the water

poses a health hazard. However, high levels of some

contaminants can improve the risk of infection,

particularly in people who are more vulnerable to

contaminants in drinking water than the general

population, such as immuno-compromised people

with cancer undergoing chemotherapy, people who

have undergone organ transplants and people with

immune system disorders. (University of Notre

Dame, 2003)

Today water quality is a real concern to both

opulation and water suppliers. They are concerned

with questions like: How good is the water I drink

today? Is the water quality becoming better or

worse? What is making the water quality better or

worse, and how can that be improved? What does a

water treatment plant need to do to make the

incoming water drinkable?

Even though most cities usually have good-

uality water, there are several concerns:

– Co

ncentrations of metals and acids in the water

are high risk.

– Hi

gh nutrient levels in water can cause algae

blooms and lower the amount of oxygen in

water. This causes the water (even when

treated) to taste strange.

– Hi

gh amounts of sediment (sand, gravel, or ash

from a burned area) clog the gills of fish and the

filters of drinking water treatment plants.

Water supply to different populations in

fficient quantities, with the best quality and the

most reasonable costs, must be one of the great

concerns of the people responsible for this area. The

major difficulties are the situation of the water tanks,

access difficulty, electric power supply and

294

Proença H., Ribeiro F., Carlos Metrôlho J. and Oliveira R. (2004).

WATER SUPPLY REMOTE MONITORING SYSTEM: A CASE STUDY.

In Proceedings of the First International Conference on Informatics in Control, Automation and Robotics, pages 296-300

DOI: 10.5220/0001137602960300

 SciTePress

communication difficulty between some stations and

those responsible for the water supply. Some remote

stations (one or more water tanks) can be in isolated

places, with difficult access, and often do not have

power supply. On the other hand, the distance

between the station and the responsible entity can be

huge. For the responsible entity to have reliable and

up-to-date information about each water tank, as

well as the amount and quality of the water, it is

necessary to implement a system that answers these

questions.

The work presented in this paper was guided by

the design and implementation of an information

system to monitor some parameters related to water

supply.

This work has been developed under an

academic research project driven by undergraduate

students in collaboration with water supplier.

In order to model the information system

developed, an object-oriented approach was

followed, namely the UML - Unified Modelling

Language (Booch et al., 1999).

This paper is structured as follows. The

following section describes the problem. An

overview of the main requirements for the system

developed is presented in section three, and our

prototype is presented in section four Finally, we

will summarise our results and make a brief

reference to some topics for future work.

2 THE PROBLEM

In some cases water quality monitoring is done by

an individual that visits each water tank and takes

samples. Often these water tanks are in places with

difficult access, making the procedure difficult and

expensive and results unreliable.

In this case we have just about one hundred

water tanks dispersed in an area of approximately

1000 Km2. Obtaining samples of all water tanks

manually, analysing each sample and making

changes in water quality control, if needed, is a slow

and expensive task that may not guarantees reliable

results. Sampling results obtained with a big delay

doesn’t allow for making corrections in time. One

way to minimize this problem is through an

information system that allows remote monitoring of

some water properties.

Real time remote sensing of the water

parameters provides information that enables

effective monitoring and control of water quality at

low cost. All this information is periodically

transmitted to the head office and stored in a

database. The system may be equipped with decision

support algorithms and applied to identifying and

controlling changes in each water tank’s properties

that are significant in improving water quality. The

consultation and administration of the data will be

carried out through the Internet.

The information system will allow real time

monitoring and detection of some atypical situations.

With real time information, it will be possible to

prevent the supply imperfections of impure water to

the populations, as well as to report on and

statistically analyse the water levels.

We have split this project into two different

stages. In stage 1 we aim to remotely monitoring the

water and pH levels in each tank. In the second stage

the main goal is to enlarge the range of controlling

fields, such as chlorine.

Having a continuous monitoring of the water

properties of each water tanks it is possible to act

much more quickly and with better results.

3 OVERVIEW OF SYSTEM

REQUIREMENTS

3.1 Main System Requirements

The developed system should deliver the required

functionality and performance to the user and should

be maintainable, dependable and usable. In the

remote monitoring environment, it is crucial to

provide fast, reliable and on-time responses when

dealing with unexpected events. These are the most

important high-level and general requirements to be

fulfilled by the system.

System requirements are usually divided into

two classes – functional requirements and non-

functional requirements. The first describe what the

system should do and is perceptible to the user,

while the second describe constraints on how the

functional requirements are implemented, and is not

necessarily perceptible to the user (Sommerville and

Sawyer, 1997).

3.2 Functional Requirements

Remote configuration. Through this requirement it

is possible to configure some parameters of the

stations remotely, namely the frequency sampling of

each sensor.

Event Notification. This feature is considered a

very important requirement, because it allows

notification in real-time if disruptive events occur in

one station, e.g. if the water level of one tank falls

below the set-point, the system sends an alert to the

person in charge of the maintenance.

WATER SUPPLY REMOTE MONITORING SYSTEM: A CASE STUDY

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Update Information. The system must allow

inquiry into stations in order to attain current data.

This will allow information of the status of any

station and its sensors in real-time.

System Management - Stations

Insert new

Station

Edit Station

Erase Station

{

}

Data Base

Administrator

{

}

Update

Station's List

{

}

PC Modem

Change time

samplings

Update station

configuration

Insert new Sensor

Erase/Deactivate

Sensor

Monitoring stations status. One efficient

strategy to reduce the risk of problems in water

supply is by better controlling aspects such as the

level and quality of the water. Monitoring the

stations brings two major benefits, namely real-time

analysis of these parameters and using the data to

produce statistical reports.

3.3 Non-Functional requirements

Performance. The system response time depends on

how sophisticated the sensors are. If the sensors are

rough (level sensors), the system will be cheaper but

not so accurate when using sophisticated sensors

(ultra-sonic).

Figure 1: Use Case diagram for Management Package.

Flexibility. The system must be flexible in order

to allow the user to insert, remove or edit elements,

such as new stations, more sensors or adding mobile

phone numbers to deliver alerts.

4 PROTOTYPE

4.1 Architecture

Usability. A friendly interface, flexible, with

strong graphical capabilities and succinct and clear

messages can raise the system efficiency.

The proposed system uses commercial hardware to

allow the acquisition of data from several sensors

(water level, pH) placed inside/near the water-tank

(properly protected against dust and other bad

effects of the environment). After the data

acquisition, with a defined sampling period, this data

is stored and sent by a remote station to the head

office station, placed in the central services office.

The person responsible for the water resources

maintenance is advised each time a disruptive event

occurs (ex. water fault in a water-tank). There are

several ways to get information about the tanks

status. The first is by a messages sent to a mobile

phone, through Short Message Service (SMS) using

Global System Mobile Communications (GSM)

technology, every time that a disruptive event

occurs. The user can also get data in real-time by

polling the desire remote stations. Finally it is also

possible to consult data stored in the database

making possible the analyses and reports of the

historical acquired data.

Power supply. In order to solve the problem of

remote stations located in isolated places, with

difficult access, and without power supply, all these

stations need to be equipped with a solar panel and a

battery.

3.4 Use Case diagram

One of the first steps considered in the modelling

was to describe the system as a number of use cases

that are performed by a set of actors.

A Use Case diagram presents a set of use cases,

actors and their relations. Their common

applications are usually divided into two - system

context modelling and system requirements

modelling. The former gives emphasis to the

identification of the boundary system, their actors

and the meaning of their functions, while the second

consist of the identification of what the system

should do, no matter how. Figure 1 illustrate some of

the Use Case diagrams considered for the system.

All these features can be accessed at any time

from a remote place, even from outside Portugal by

the World Wide Web site, through an Internet link.

To implement this feature we used PHP technology.

With this access the user can consult the data stored

in the host PC, located in the central monitoring

office and define the set-points for the controlled

variables. The architecture of the implemented

system is shown in Fig. 2.

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Central PC

Modem

GSM

RDBS

WWW Server

GSM

RS232

Intranet

Internet

Remote user

Head Office

Remote Station 1

...

GSM

Modem

Sensor 1 Sensor n

Remote Station n

...

GSM

Modem

Sensor 1 Sensor n

Figure 2: Architecture of the proposal system.

4.2 System Implementation

To implement the proposed system, commercial

hardware was used and software was developed to

reach the desired goals. In the next part of this paper

we will summarise the main blocks.

Hardware

To acquire data we use a Programmable

Controller (FPO-T32CP, 2003) that acts as an

interface between the sensors, physic world, and a

GSM modem. The used programmable controller

will allow, in a future stage of the system

development, digital control over actuators like

valves or other such features. Some features of the

used controller are:

– 32 I/O points (16 Input and 16 Output) with

expansion until 128 I/O points;

– Program capacity of 10K steps;

– Operation speed (central value/step) of 0.9ms ;

– Programme memory uses EEPROM or RAM;

– 100 subroutines;

– Several special functions;

– self-diagnosis functions;

– Password setting;

– Run time editing;

– Built-in functions for interrupt processing, high

speed counting and pulse output;

– 24 VDC operating voltage;

– RS232 serial port for connection to intelligent

devices or modems for telemetry applications.

In this acquisition stage commercial level

sensors had been used to read the water level values

inside the water tank.

To allow the communication between remote

places and the central system two types of GSM

modem were used. One from Matsuhita (Fastrack,

2004) and one from siemens (M20, 1999) whose

features are detailed in the referenced documents

and web sites.

The implemented remote station prototype is

shown in the following photo:

Figure 3: Photo of the implemented remote station

prototype.

Software

The software component of the system uses

several different languages/technologies: mySQL

(MySQL, 2004), PHP (PHP, 2004), HTML, Control

FPWIN Pro (Control FPWIN Pro, 2003) Its usage is:

– MySQL is used as support of the database,

where the data read by the PLC is stored, but

also to allow queries to the database, for its

manipulation. The data manipulation is

WATER SUPPLY REMOTE MONITORING SYSTEM: A CASE STUDY

297

basically the actions of average calculation,

maximum value calculation, minimum value

detection, data sort, etc.

– PHP is used to allow the connection with the

database. The connection is done using an

ODBC redirected to the database.

– HTML was used to build a WEB page. This

page allows in “real time” the graphical

presentation of the data read by the logger.

HTML also uses PHP to accede to the database,

using SQL queries embedded in PHP.

– FPWIN Pro is used in the remote acquisition

station to allow the acquisition of data from

sensors and transmission of the sampled data to

the central system. This tool is Matsushita

programming software. It allows 5 different

languages (instruction list. Ladder diagram,

structured text, function block diagram and

sequential function chart).

5 CONCLUSIONS AND FURTHER

WORK

The results of the stage one of the described work

are encouraging.

Tests have been made regarding the remote

station based on the defined message protocol. With

also test alarm conditions scenarios, namely lack of

water and high pH level. The results have been

excellent.

On the head office block of the system the data

storage, the SMS communication and the reports

analyses have also been implemented.

Further work will involve the refinement of the

remote stations, namely stage two, i.e. adding more

sensing and actuation equipment. We aim to test the

system under full charge (critical conditions).

We plan to have the full developed system in

July 2004.

REFERENCES

Booch, G., Rumbaugh, J. and Jacobson, I. (1999). The

Unified Modeling Language User Guide, Addison

Wesley.

Control FPWIN Pro, Programmable Controller FPO

catalogue, Matsuhita Electric Works, 2003. [online]

Available: www.matsuhita.es, catalogue page 19.

Fastrack M1203A-ON GSM/GPRS Modem,

www.wavecom.com [website consulted in 26-

February-2004].

FPO-T32CP, Programmable Controller FPO datasheet,

Matsuhita Electric Works, 2003. [Online] Available:

www.matsuhita.es, catalogue page 17.

M20 Cellular Engine Siemens terminal, Siemens

Information and Communication products, Version 5,

1999.

MySql Ab. [online]. Available: http://www.mysql.com/

PHP. [online]. Available: http://www.php.net/

Sommerville, I. and Sawyer, P. (1997). Requirements

Engineering: A Good Practice Guide, John Wiley &

Sons. Chichester.

University of Notre Dame (2003), Annual Drinking Water

Quality Report, Consumer Confidence Report 2003,

available: www.nd.edu/~riskman/manuals/documents/

waterqualityrpt2002_000.doc

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