Key Engineering Materials Vol 605 (2014) pp 47-50 Online: 2014-04-03

© (2014) Trans Tech Publications, Switzerland

doi:10.4028/www.scientific.net/KEM.605.47

Wireless Sensor Network-based Water Quality Monitoring System

Gurkan Tuna1,a, Bilel Nefzi2,b , Orhan Arkoc3,c and Stelios M. Potirakis4, d
1
Department of Computer Programming, Trakya University, Edirne, Turkey
2
Independent Research, Paris, France
3
School of Technical Sciences, Kirklareli University, Kirklareli, Turkey
4
Department of Electronics Engineering, Technological Education Institute (TEI) of Piraeus,
Aigaleo, Greece
a b c d
gurkantuna@trakya.edu.tr, bilel.nefzi@live.com, orhan.arkoc@kirklareli.edu.tr, spoti@teipir.gr

Keywords: Water quality, WSN-based water quality monitoring, web-based online interface.

Abstract. Water is vital for both nature and human beings. The construction of dams and
embankments, the irrigation practices, and the anthropogenic activities influence water quality. In
order to control water quality, it is essential to understand the sources of pollutants. Water quality
monitoring requires the collection of large numbers of samples and long delays until the results are
available. Therefore, rapid monitoring of water quality is very important. In this respect, numerous
systems exist for this kind of automatic monitoring. In this study, we propose a wireless sensor
network (WSN)-based monitoring system controlled by a web-based online interface which allows
the remote monitoring via Internet. This brings advantages over traditional monitoring systems in
terms of cost effectiveness, portability and applicability. Field tests in the water reservoir of
Kirklareli (Kirklareli dam), Turkey, are in progress.

Introduction
The demand for good quality drinking water has increased rapidly nowadays [1]. The usage of
water depends on its suitability for the different intended purposes. Therefore, the quality of
groundwater is very important as well as its quantity [2]. It is well known that contaminated inflows
degrade the water quality of lakes and reservoirs in many countries. Therefore, the continuous
monitoring of water quality is essential to ascertain the sources of pollutants in order to take
measures to prevent pollution. European Water Framework Directive (WFD) is the main reference
guide for preserving aquatic environment in Europe. Dissolved oxygen (DO), pH, electrical
conductivity (EC), temperature, turbidity and nitrate are the main parameters for determining the
water quality as stated by WFD [3] and US EPA [4]. Generally, water quality assessment chemical
analyses are done at laboratories, causing considerable delays in water quality monitoring. In this
respect, the real time monitoring is important for the on-time warning of authorities and people.
Due to the offered advantages, portable water quality analysis systems have drawn the attention
of research communities during the last years. Multi-probe Sondes with sensors for measuring water
quality parameters were used to analyze water quality in different case studies, e.g., [5,6]. Due to the
increasing interest in wireless sensor networks (WSNs), the use of WSNs in water quality
monitoring systems has been proposed in several studies, e.g., [7-9]. Since WSNs consist of battery-
operated wireless sensor nodes, to deal with the need for battery replacement and maintenance, the
use of energy harvesting techniques [10-11], attract the attention of researchers.
In this paper, a WSN-based monitoring system is proposed to assess water quality. The proposed
system consists of several portable water quality monitoring nodes with wireless interfaces and
periodically measures major water quality parameters such as EC, DO, pH, temperature, turbidity
and nitrate. In the proposed system, the nodes form a WSN and send their measurements to a web
server through a gateway. The system has many advantages over traditional laboratory-based water
quality analyses including cost-effectiveness, accuracy, portability and rapid assessment.

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48 Materials and Applications for Sensors and Transducers III

WSN-based Water Quality Monitoring System

A wireless sensor node principally consists of a microcontroller, a storage unit, A/D converters, a
radio transceiver module, a battery, and sensors for measuring different environmental parameters.
It converts data frames carrying measurements to radio messages and sends these frames to a
gateway, generally called “sink”. A wireless sensor network (WSN) is composed of several wireless
sensor nodes distributed over an area in order to observe some phenomenon. In WSNs, nodes
automatically establish and maintain connectivity by using mesh-networking protocols. The sensor
gateway and its associated middleware enable the WSN to communicate with the outside world.
In this study, water quality parameters including EC, DO, pH, temperature, turbidity and nitrate
are monitored by a WSN. In this system, portable water quality monitoring nodes with probes for
water analyses mounted on buoys monitor water quality at specified time intervals. The nodes form
a WSN and send their measurements to the web server through the gateway. Similar to the system
proposed in [12], the gateway provides connection between the WSN and a web server which is
located at the control center of a utility provider. The web server provides a data repository to store
the measurements and render the measurements available to Internet users.

Web-based Online Interface

Fig. 1. Online interface of the water quality monitoring system. Note that the details of a specific
node can also be shown by clicking the corresponding mark on the map.

A web-based interface has been developed for the WSN-based water quality monitoring system.
Through this interface, utility providers and subscribers can easily check the quality of their water.
Depending on the configuration of the water quality monitoring nodes, the measurements shown on
the interface are refreshed at specified time intervals such as 15 min, 30 min, 1 hour, 6 hours, 12
hours, and 1 day. Since the web server stores all the data, the utility providers and customers can
also look at the measurements referring to a specific time. Through the administration screen, the
interface also allows to adding new nodes and new water quality parameters. Fig.1 shows a
characteristic screen of the developed online interface.

Performance Evaluation
A set of performance evaluation scenarios was run on emulated hardware to investigate how the
different parameters of the WSN are affecting its efficiency in terms of network performance. The
emulated scenarios revealed that there is a trade-off between the parameters of the WSNs, like
packet generation interval, packet length, packet reception rate, average percentage of time during
which the nodes are active, transmit, or receive, etc. Therefore, it is necessary to evaluate the
 Key Engineering Materials Vol. 605 49

parameters and balance the trade-off between them before real-world deployments are attempted.
An example of the obtained results is shown in Fig. 2. The specific scenario involved a group of
water quality monitoring nodes and its objective was to evaluate the performance of the WSN when
the number of nodes varies.

Fig. 2. As the number of nodes increases: (a) the packet reception rate reduces, and (b) the average
percentage of time during which the WSN nodes transmit/receive increases. All the nodes in this
scenario are within 1 hop. Main parameters of this scenario: Packet generation interval = 5s
(periodic with a different random offset for each node), Application packet length = 23 octets, MAC
: CSMA/CA and contikiMAC with an 8 Hz check rate, Radio Model : MRM, Tx: not directional,
Rx Sensitivity = -85 dB.

Fig. 3. Nitrate analysis of the case study.

Furthermore, a sample dataset was created in order to show the practical use of the proposed system.
Using this dataset, a set of Geographic Information System (GIS)-based simulation studies was
conducted. An example of the results of these simulation studies is given in Fig. 3. From this figure,
it is evident that the proposed system provides eloquent water quality color-maps to utility providers
and customers and in this way helps to visualize different water quality parameters.

Conclusions
This paper presents the details of a WSN-based water quality monitoring system and presents
results from simulation studies conducted in order to show the associated design challenges which
affect the overall effectiveness of the proposed system. The proposed system eliminates the need for
50 Materials and Applications for Sensors and Transducers III

periodical time-consuming water quality analyses and helps the improvement of the quality of the
supplied water through continuous monitoring. At the same time, it brings cost advantages to utility
providers by eliminating periodical laboratory expenses. The proposed system utilizes a group of
portable Sondes with solar panels for energy harvesting and IEEE 802.15.4–based wireless
interfaces mounted on buoys. The Sondes form a WSN to communicate over and send their
measurements at regular time intervals to a central PC over the WSN. As proven by the presented
simulation results, the applicability of the proposed system depends on several parameters such as
transmission frequency, transmission power, packet size and node-related parameters. Our future
work concerns the conduction of field tests at a drinking water reservoir.

References
[1] S. Chakrabarty, H. P. Sarma, Heavy metal contamination of drinking water in Kamrup district,
Assam, India, Environmental Monitoring and Assessment. 179 (2011) 479-486.
doi:10.1007/s10661-010-1750-7.
[2] O. Arkoç, Assessment of scaling properties of groundwater with elevated sulfate concentration:
a case study from Ergene Basin, Turkey, Arabian Journal of Geosciences. (2012)
doi:10.1007/s12517-012-0704-5
[3] Directive 2000/60/EC (2000). Water Framework Directive of the European Parliament and of
the Council of 23 October 2000 establishing a framework for community action in the field of water
policy. Official Journal L, 327 Available at: http://eur-lex.europa.eu/LexUriServ/
LexUriServ.do?uri=CELEX:32000L0060:EN:NOT (accessed 11/03/2013)
[4] US EPA (2003). Groundwater and drinking water, drinking water standards. United States
Environmental Protection Agency. Available at: http://www.epa.gov/safewater (accessed
11/03/2013)
[5] J. Wang, L. Zhu, G. Daut. J. Ju, X. Lin, Y. Wang, X. Zhen, Investigation of bathymetry and
water quality of Lake Nam Co, the largest lake on the central Tibetan Plateau, China, Limnology. 10
(2009) 149-158.
[6] D. R. Lapen, E. Topp, M. Edwards, L. Sabourin, W. Curnoe, N. Gottschall, P. Bolton, S.
Rahman, B. Ball-Coelho, M. Payne, S. Kleywegt, N. McLaughlin, Effect of Liquid Municipal
Biosolid Application Method on Tile and Ground Water Quality, Journal of Environmental Quality.
37 (2008) 925-936.
[7] J. V. Capella, A. Bonastre, R. Ors, M. Peris, In line river monitoring of nitrate concentration by
means of a Wireless Sensor Network with energy harvesting, Sensors and Actuators B. 177 (2013)
419-427.
[8] J. V. Capella, A. Bonastre, R. Ors, M. Peris, A Wireless Sensor Network approach for
distributed in-line chemical analysis of water, Talanta, 80 (2010) 1789-1798.
[9] F. Regan, A. Lawlor, A. McCarthy, SmartCoast Project – Smart Water Quality Monitoring
System (STRIVE Report Series No. 30). http://www.epa.ie/downloads/pubs/research/tech/
STRIVE_30_Regan_SmartCoast_syn_web.pdf (accessed 11/03/2013)
[10] H. A. Ma, J. Q. Liu, G. Tang, C. S. Yang, Y. G. Li, D. N. He, A broadband frequency
piezoelectric vibration energy harvester, Key Engineering Materials. 483 (2011) 626-630.
[11] K. Zhou, F. Xie, T. Yi, Piezoelectric energy harvester for wireless sensors, Key Engineering
Materials. 546 (2013) 147-149.
[12] J. Tomić, M. B. Živanov, M. Kušljević, Đ. Obradović, J. Szatmari, Realization of measurement
Station for remote environmental monitoring, Key Engineering Materials. 543 (2013) 105-108.
Materials and Applications for Sensors and Transducers III
10.4028/www.scientific.net/KEM.605

Wireless Sensor Network-Based Water Quality Monitoring System

10.4028/www.scientific.net/KEM.605.47

DOI References
[1] S. Chakrabarty, H. P. Sarma, Heavy metal contamination of drinking water in Kamrup district, Assam,
India, Environmental Monitoring and Assessment. 179 (2011) 479-486. doi: 10. 1007/s10661-010-1750-7.
http://dx.doi.org/10.1007/s10661-010-1750-7
[5] J. Wang, L. Zhu, G. Daut. J. Ju, X. Lin, Y. Wang, X. Zhen, Investigation of bathymetry and water quality
of Lake Nam Co, the largest lake on the central Tibetan Plateau, China, Limnology. 10 (2009) 149-158.
http://dx.doi.org/10.1007/s10201-009-0266-8
[7] J. V. Capella, A. Bonastre, R. Ors, M. Peris, In line river monitoring of nitrate concentration by means of
a Wireless Sensor Network with energy harvesting, Sensors and Actuators B. 177 (2013) 419-427.
http://dx.doi.org/10.1016/j.snb.2012.11.034
[10] H. A. Ma, J. Q. Liu, G. Tang, C. S. Yang, Y. G. Li, D. N. He, A broadband frequency piezoelectric
vibration energy harvester, Key Engineering Materials. 483 (2011) 626-630.
http://dx.doi.org/10.4028/www.scientific.net/KEM.483.626
[11] K. Zhou, F. Xie, T. Yi, Piezoelectric energy harvester for wireless sensors, Key Engineering Materials.
546 (2013) 147-149.
http://dx.doi.org/10.4028/www.scientific.net/KEM.546.147
[12] J. Tomić, M. B. Živanov, M. Kušljević, Đ. Obradović, J. Szatmari, Realization of measurement Station
for remote environmental monitoring, Key Engineering Materials. 543 (2013) 105-108.
http://dx.doi.org/10.4028/www.scientific.net/KEM.543.105