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DESIGN AND DEVELOPMENT OF SMART IRRIGATION SYSTEM FOR WATERING
ROOFTOP GARDEN
Rokon Uz Zaman
Agricultural Engineering Division, Bangladesh Agricultural Research
Institute, Bangladesh.
Email: rokonae99@gmail.com
ABSTRACT
Article History
Received: 19 January 2022
Revised: 24 February 2022
Accepted: 10 March 2022
Published: 30 Marh 2022
Keywords
Automatic drip
Smart drip
Rooftop irrigation
Rooftop garden.
Rooftop gardening is one of the famous agricultural technology in urban areas of many
countries including Bangladesh. Crop water requirement is very high in rooftop due to
high temperature and high evapotranspiration. Irrigation as well as water management
is the major limitation for this practice. Considering the necessity of rooftop gardening
in urban areas and irrigation issue, it is essential to develop a low cost efficient irrigation
method that helps to improve production techniques for rooftop garden. From this study,
we developed a smart irrigation system for watering rooftop gardening where mainly
used programmable digital timer, solenoid valve and electric pump operated drip system.
In this irrigation system, programmable digital timer sends a signal to the solenoid valve
and electric pump that leads to open or close the whole irrigation system and crop was
watered the selected interval and frequency wise. From the results, average discharge
(Qavg), distribution efficiency (Ed), application efficiency (Ea), coefficient of variation for
emitter flow (cv) and statistical uniformity coefficient (SUC) were achieved good
performance and was found meeting American Society of Agricultural Engineers (ASAE)
standards. The designed smart irrigation system was operated excellently as the values
of emission uniformity.
Contribution/Originality: This system having small water pump which connected to roof top water tank and
automated off-on the water pump at selectable interval. Automatic system was controlled by digital timer. As a new
concept, the study is original.
1. INTRODUCTION
Rooftop gardening is popularizing day by day in urban areas of world including Bangladesh. Water is a key
element and most vital factor for promoting urban rooftop agriculture [1]. But crop watering method is the major
limitation for this practice. Generally, more than 90% of rooftop gardeners applied traditional irrigation method using
local traditional tools such as mugs, hose pipes, etc. from their own groundwater source [2-5]. The main obstacles
of traditional water application method is manually, time consuming, waste huge valuable water and discourage the
rooftop gardening. There are many research suggested that drip irrigation method is more suitable for watering
rooftop garden than others. Drip irrigation system where applying irrigational water directly to the root zone, could
be an efficient method to increase water use efficiency and irrigation management in the rooftop garden [6, 7]. Drip
irrigation could be an efficient method of irrigation for rooftop gardening which has some advantages like reduces
human effort for irrigation management in the rooftop garden, applies correct water amounts precisely when required
to maintain optimum available soil moisture in the root zone [8] reduces management time required for observing
plant water needs and manually controlling irrigation systems [9]. Drip irrigation systems are classified gravity feed
Review of Plant Studies
2022 Vol. 9, No. 1, pp. 12-18.
ISSN(e): 2410-2970
ISSN(p): 2412-365X
DOI: 10.18488/rps.v9i1.2948
© 2022 Conscientia Beam. All Rights Reserved.
Review of Plant Studies, 2022, 9(1): 12-18
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© 2022 Conscientia Beam. All Rights Reserved.
and forced feed basis on their water feeding system. Recently, a few number of rooftop gardening irrigation systems
are designed by gravity feed system. The main limitation of gravity feed drip irrigation for roof top gardening is
having lower pressure that causes to low emitter discharge and watering less number of plant. Besides, the flow of
water can be changed due to change in water level in the reservoir tank due to positive hydraulic pressure system.
For these motives fixed flow was not possible using conventional drip irrigation system. To get appropriate pressure
for this system required to keep the water tank above the 20 to 60 ft height. It is cost effective and need to constructed
extra-large structure on the building roof for placement of water tank. This extra-large structure causes destroyed
the beatification. Therefore, present study was aimed to design and development of a smart irrigation system for
watering rooftop garden and to evaluate the performance of developed system. This system having small water pump
which connected to roof top water tank and maintained automated off-on the water pump at specific interval.
2. MATERIALS AND METHODS
2.1. Architecture of Smart Irrigation System
The proposed smart irrigation system was designed by the following given flow chart Figure 1. The materials
that were successfully used for construction and installation of smart irrigation systems were: Water tank (plastic),
Electric pump, Solenoid Valve, Programmable timer, Main line pipes, Elbow Joining, Sub main line pipe, lateral pipes,
micro emitters. Digital timer and wi-fi controller switch both are used for controlling solenoid valve and pump. This
study, digital timer is used instead to wi-fi controller switch. The wi-fi controller switch also be used this system
where internet connection is available.
Figure 1. Flow chart of proposed smart irrigation system.
2.2. Water Reservoir Tank
Generally water distribution system of building, main water supply line was connected with water source and
electric pump was used to pump the water to store in a water reservoir tank on rooftop. The water reservoir tank of
this system was placed on a stage or water reservoir basement at rooftop. The basement height is 6 inches. Different
size of water tank was selected for this system. The plastic tank was chosen as a water reservoir to reduce the water
temperature for beater crop performance. Besides, plastic materials are free from the problem of rust due to stagnant
water.
2.3. Electric Pump
In this system electric pump is used to takes water from the source and provides the right pressure for delivery
into the pipe system. This pump was automated off-on by programmable digital timer. The programmable timer
sends a signal to the pump and it to start or off. At this study used to 0.5hp electric pump to supply water for the
plant and connected to water tank.
Review of Plant Studies, 2022, 9(1): 12-18
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© 2022 Conscientia Beam. All Rights Reserved.
2.4. Water Filter
The quality and cleanliness of the water is a major consideration of drip irrigation system designing. For the
dirty water which is coming from ponds, rainwater or any open water catchment tanks must be used water filter.
However, the water coming from a municipal water source or storage container free of debris and thoroughly filtered.
So, there were no needs to used water filter. If we decided to use filter must be used before valve.
2.5. Solenoid Valve
In smart irrigation system, a solenoid valve is designed to be used with a digital timer. Generally, solenoid valves
are used for automatic drip systems having arrow of its side that indicates the direction of the flow of water. The
solenoid valve is always installed horizontally and downstream side of pump and controlled by electrical power, which
is run through the coil. The programmable digital timer sends a signal to the valve telling it to open or close.
Figure 2. Solenoid valve.
2.6. Programmable Digital Timer
The battery (2A) operated programmable digital timer is used at this system that connects directly to the solenoid
valve and electric pump. This timer is manually selector system and simple to program with two dial segments like
irrigation frequency 1-2-3-4-6-8-12 hours or 1-2-3 days and irrigation duration 1-3-5-10-15-20-30-60-90-120
minutes. The timer has 4 terminals where 2 terminals for clock (or Power) and 2 terminals for switch. When the
rated voltage was connected to clock terminals then clock terminals have power and the switch terminals receive NO
power. This simple on-off switch can control any voltage 120V, 240V, 277V, 24V. If connect one hot wire to either
switch terminal, and then connect wire going to load to other switch terminal.
Figure 3. Programmable digitizing timer.
2.7. Main Line and Sub Main Selection
The main line of drip was designed with a 16 mm diameter black flexible low density poly polyethylene (LDPE)
pipe with 1.2mm thickness.
2.8. Laterals Selection
The lateral lines of drip were designed with a 4 mm diameter black flexible low density poly polyethylene (LDPE)
pipe with 1.2mm thickness. The diameter of pipe was reduced to increase the pressure of water flowing through the
laterals in the micro tube emitters.
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© 2022 Conscientia Beam. All Rights Reserved.
2.9. Dripper Selection
Adjustable micro dripper (4mm) was selected at this drip system to easily change the flow rate. Besides,
adjustable micro drippers tend to vary greatly in flow and having little pressure compensation.
3. RESULTS AND DISCUSSIONS
Programmable digital timer controls the total irrigation system Figures 4-5. In this system, at first program was
manually set in the timer, like irrigation frequency and interval based on crop water requirement. Prog rammable
digital timer sends a signal to the solenoid valve and electric pump to open or close and crop was watered selected
interval and frequency wise. The main advantage of this system was there was no need manually off-on the pump
switch. Besides, no need extra labor for irrigation management. The performance of automation function of the digital
timer is excellent. A single sub line is used for one row of peppers (drip lines are therefore also 7 ft apart). Let’s say
our rooftop garden is 70 ft long and 50 ft wide. Each row contains 10 plants and plant to plant, row to row distance
is 7ft and 10ft respectively. The 0.5hp pump is used for this experiment. This system is installed for 50 plants Figures
4-5 and extended to 150 or more plant. Average discharge of emitter should be decreased with increased the number
of plant for constant pump discharge. For this condition, we adjust the irrigation duration and interval by using
digital timer.
3.1. Performance Evaluation of Developed Smart Irrigation System
Developed smart irrigation system for watering rooftop garden is one kind of drip irrigation that controlled by
digital programmable timer. As a result, the performance evaluation method of this system is similar to the drip
system which was evaluated based on the following parameters:
Figure 4. Layout of smart irrigation system for rooftop garden.
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© 2022 Conscientia Beam. All Rights Reserved.
Figure 5. Pictorial view of smart irrigation system for rooftop garden.
3.2. Distribution Efficiency
The distribution efficiency of irrigation system was calculated by used the statistical method which introduced
by Wu and Gitlin [10] and suggested by Christiansen. They gave the following equation:
Where, = Average absolute deviation from the mean discharge rate.
= mean discharge rate, (l/h).
3.3. Application Efficiency
The application efficiency is denoted as the ratio of water required in the root zone to the total amount of water
applied and expressed by;
Where, = application efficiency, %.
= minimum emitter flow rate (l/h).
= average emitter flow rate (l/h).
The uniformity of water application of drip irrigation system expressed by two parameters namely field emission
uniformity (EUf) and absolute emission uniformity (EUa), suggested by Keller and Karmeli [11].
3.4. Field Emission Uniformity (EUf)
This is used to describe the emitter flow variation for a micro irrigation unit. It is expressed by;
Where,
= average of the lowest 1/4 of the emission point discharges for field data, l/h.
= The average of all emitters flow rate (l/h).
Absolute emission uniformity (EUa).
Where,
= minimum flow rate through emitter, l/h.
= average flow rate through emitter (l/h).
= average of the highest 1/8th of the emitters flow rate (l/h).
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© 2022 Conscientia Beam. All Rights Reserved.
3.5. Coefficient of Variation (Cv)
Coefficient of variation for emitter flow is expressed by;
3.6. Statistical Uniformity Coefficient
Statistical uniformity coefficient of emitter flow;
Table 1. Performance parameters to evaluate irrigation system.
Average
emitter
discharge
Q avg (l/h)
Distribution
efficiency
Ed (%)
Application
efficiency
Ea (%)
Field
emission
uniformity
EUf (%)
Absolute
emission
uniformity
EUa (%)
Coefficient
of variation
Cv
Statistical
uniformity
coefficient
SUC (%)
29.55
97.06
93.16
96.85
94.10
0.029
97.05
The results of different parameters Table 1 like distribution efficiency (Ed), application efficiency (Ea), field
emission uniformity (EUf) , absolute emission uniformity (EUa), coefficient of variation for emitter flow (cv) and
statistical uniformity coefficient (SUC) were achieved good performance and was found meeting ASAE standards.
The high value of SUC and low value of Cv was indicated a good performance of the system. The excellent emission
uniformity was observed that indicated water is distributed uniformly.
4. CONCLUSION
From the results of the installed and tested this smart irrigation system will become easy and comfortable for
watering rooftop garden. The electric pump and solenoid valves are successfully OFF-ON by programmable digital
timer. The performance of digital timer is perfect to maintain irrigation interval and duration. This smart irrigation
system can not only be used in a rooftop garden but can be used in garden.
Funding: This research is supported by Bangladesh Agricultural Research Institute (Grant number:
12.21.0000.034.09.004.20.542).
Competing Interests: The author declares that there are no conflicts of interests regarding the publication
of this paper.
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