IJERD – International Journal of Environmental and Rural Development (2015) 6-2

Research articleerd

Micro Hydroelectricity Using Irrigation Ponds for Better
Water Management
KATSUYUKI SHIMIZU*
Faculty of Agriculture, Tottori University, Tottori, Japan
Email: shimizu@muses.tottori-u.ac.jp

YASUYUKI KUSAKA
Sanyu Consultants INC, Nagoya, JapanYOSHINOBU KITAMURA
Arid Land Research Center, Tottori University, Tottori, Japan
Received 22 January 2015

Accepted 15 July 2015(*Corresponding Author)

Abstract This paper discusses estimates of hydroelectricity potential using irrigation ponds inmountainous areas. Hydroelectric power output is calculated from hydrological observations
such as discharge from the ponds and water level at two irrigation ponds. Although these ponds
have almost the same water storage capacity, water discharge patterns differ due to differencesin the command areas. Results show that water management influences the pattern ofhydroelectric power generation. The use of electricity is also important to consider sinceirrigation ponds in mountainous areas are distant from villages, which have no electricity
infrastructure. In most cases, the irrigation ponds in mountainous areas are difficult to access. In
addition, most of the water managers are aging and are having difficulty maintaining irrigation
ponds and its water management. Therefore, using hydroelectric power to support the operationand maintenance of irrigation ponds would be one of the best ways to use the hydroelectric
power generated at irrigation ponds. Finally, a field experiment of a micro-hydroelectricity
system is conducted at an irrigation pond and the pond monitoring system is installed.
Keywords renewable energy, siphon intake, automatic control, monitoring system

INTRODUCTION
Irrigation ponds are used as supplemental irrigation for paddy rice fields in Japan. Recently, thegeneration of micro hydroelectricity using irrigation facilities as a form of renewable energy hasreceived much attention due to encouragement by the Japanese government and the significant priceincreases in electric power. Irrigation ponds, especially those located in mountainous areas, can easily
generate the gravitational drop, which is necessary for hydroelectricity generation and gives advantage
to ponds in these areas more than the ones in flat areas.
Lots of investigations have been conducted by the government and local governments so thegovernments can estimate hydroelectricity potential in mountainous areas in Japan. However, most ofthem were calculated only by using topographic information and rainfall data without considering
actual water management. Ueda et al. (2013) have reviewed small-scale hydropower generation using
irrigation water in Japan. Ueda et al. (2015) had conducted a scenario analysis to propose a water
management scheme to balance two objectives, irrigation and hydropower. There is no research onhydropower generation using small irrigation ponds, as there are many in mountainous areas especiallyin western part of Japan.
Therefore, this paper discussed and estimated hydroelectricity potential using Nanatani pond andMatsutani irrigation ponds in Tottori, Japan and the use of electricity by considering current waterⒸISERD73

IJERD – International Journal of Environmental and Rural Development (2015) 6-2

management practices. Moreover, field experiment of hydroelectricity was conducted at Yanaka pondin Tottori.
METHODOLOGY
Irrigation ponds are categorized into two groups, including ponds in mountainous areas and in flat
areas. In this paper, siphon intake is assumed to estimate the hydroelectricity potential using irrigation
ponds in mountainous areas. There are advantages of employing siphon intake, such as preventing dust
entering, making use of water head for hydroelectricity, reducing initial investment for hydroelectricity,and easier water management than conventional practices.
Study Areas
Two irrigation ponds, Nanatani and Matsutani, were selected in this study. Both of them are located in
mountainous areas of Tottori Prefecture, Japan. Storage capacities of the two ponds are more than
200,000 m3 and the height of both ponds are over 12 m. Considering more than 50% of irrigation
ponds in Tottori, the ponds have less than 10,000 m3 of water storage capacity, which are relatively
big ponds. Besides, there were significant differences in beneficiary areas and catchment areas.
Catchment areas of Nanatani pond were about half of the Matsutani’s one while beneficiary areas ofNanatani were more than 3 times of the Matsutani’s one. Water was collected from runoff of eachcatchment area only and there was no water supply from river water. General descriptions of theselected irrigation ponds are summarized in Table 1.
Table 1 General information about observed ponds
Name of Pond
Storage capacity (10,000 m3)
Dam height (m)Catchment area (ha)Beneficiary area (ha)Water resource

Nanatani
210.0
12.0
30.0
44.5
RunoffMatsutani
259.2
16.5
62.0
13.0
RunoffHydrological Observation and Estimation of Hydroelectricity
Siphon intake was assumed in this study instead of conventional operation. The opening and closing
bulbs on inclined inlet pipe were employed to make use of advantages of siphon for hydroelectricity
such as avoiding trash intake, easier operation of open and close gate, and getting water head and lower
cost. The outlines of hydroelectric system are illustrated in Fig. 1.
Also, hydroelectric power output (kW) is calculated as following Eq. 1.
𝑃 = 𝜌𝑔𝐻𝑒 𝑄 𝜂(1)3Where, P is electric output (kW), 𝜌 is density of water (1,000kg/m ), g is gravity acceleration (9.8m/s2), He is effective head (m), Q is discharge (m3/s), 𝜂 is efficiency (0.601).
Water levels of irrigation ponds and canals were monitored in every 10 minutes during irrigationseason in 2010 and 2011. A level survey was conducted to determine the head and for hydrologicalobservations such as discharge from the ponds and water level. Height-volume curves of irrigations
ponds and height- discharge curves of irrigation canals were also prepared for the two ponds based on
the field survey.

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IJERD – International Journal of Environmental and Rural Development (2015) 6-2Fig. 1 Outlines of hydroelectric system
Field Experiment
Field experiment of siphon intake and hydroelectricity was conducted at Yanaka pond in Tottori during
non-irrigation period. Usage of generated electricity was also demonstrated such as installing electricbulb for easier water management and or monitoring system to inform water managers for the waterlevel of the ponds.
RESULTS AND DISCUSSION
Estimated Hydroelectricity
Fig. 2 (a) shows the estimated power output of Nanatani pond in 2010. Irrigation period is 106 days
from May 30 to September 12. Water discharge varied daily because water managers conventionally
opened the gate at 6 a.m. and close at 6 p.m. Water manager also adjusted the discharge according torainfall events. If it rained at 6 a.m., the water manager would not discharge water. If it rained atdaytime, the manager would go to the pond to decrease and/or stop discharge.
Fig. 2 (b) shows estimated power output of Matsutani pond in 2010. Irrigation period is 104 days
from June 1 to September 12. Compared with Natanani pond, Water level and discharge at Matsutani
pond were more stable. Irrigation water was released 24 hours and water discharge was adjusted every
3-4 days at Matsutani pond.
Table 2 Summary of the estimated output, 2011
Pond
Gross generation (kWh)Total discharge (103 m3)
Maximum output (kW)Average output (kW)Monitoring time (h)Discharge time (h)Generating time (h)CO2 conversion (kgCO2)
Oil conversion (L)NanataniMatsutani

1,821.0
199.7
5.0
1.7
2,538.0
1,080.0
1,080.0
1,011.0462.6

3,443.0
265.2
3.6
1.3
2,610.0
2,610.0
2,610.0
1,911.0
874.5

Table 2 shows the results of estimated hydroelectricity of two ponds for the year of 2011. The
maximum electric power output and electric power were 4.92 kW and 1,420 kWh at Nanatani pondand 3.57 kW and 3,000 kWh at Matsutani pond. Although these ponds had almost the same water
storage capacity, water discharge patterns differed due to differences in the command areas. NanataniⒸISERD75

IJERD – International Journal of Environmental and Rural Development (2015) 6-2

pond had larger command area than Matsutani pond; therefore, strict water management was practiced
at Nanatani pond. The water manager at Nanatani pond usually opened the gate at 6 a.m. and closed at
6 p.m., and the water gate was closed when it rained. On the other hands, the water manager at
Matsutani pond usually kept the gate opened and the discharge was controlled twice a week during theirrigation period. Therefore, the water level of the pond decreased continuously at Matsutani pond
while the water level of the pond slowly decreased at Nanatani pond due to its strict water management.
As a result, hydroelectric power was continuously generated at Matsutani pond compared withNanatani pond. It shows that water management influences the pattern of hydroelectric powergeneration.
Result of Field Experiment
A field experiment of a micro-hydroelectricity system was conducted at Yanaka irrigation pond inTottori, Japan. Electricity output was also continuously monitored in two weeks to examine thestability of output. Fig. 3 shows the results of field experiment. Stable output about 1.2 kW wasobserved during the first 10 days from February 1 to 10. Then the output decreased according to thelowering of water level in the pond.

(a) Nanatani
pond ParkNanataniPondHigashiyama(b) Matsutani pond
Fig. 2 Estimated power output at observed ponds, 2010 (Kusaka et al., 2011)(Discharge: 52 L/s, Generating efficiency: 45~50%)

Fig. 3 Power output of the field experimentⒸISERD76

IJERD – International Journal of Environmental and Rural Development (2015) 6-2

Usage of Generated Electricity
The usageof the electricity was also important since irrigation ponds in mountainous areas were distantfrom villages and had no electricity infrastructure. Consequently, the electricity generated at ponds
could not be readily used by villagers and farmers. In most cases, it was observed that the farm ponds
in mountainous areas were difficult to access. In addition, most of the water managers were aging, over
65 years old, and were having difficulty in maintaining farm ponds and their water management(Taniguchi et al., 2011). Using hydroelectric power to support the operation and maintenance anirrigation pond, replacing manpower, and fuel with electricity would be one of the best ways to togenerate electricity at a farm pond. Moreover, some water managers havd problems with illegal
disposal of cabbages into the ponds and illegal fishing by fishermen who deliberately discharged water
to lower the water level in the ponds for easier fishing. However, since the location of irrigation ponds
were far from the villages, water managers could not check the ponds often.

Pic. 1 Installation of an electric bulb
(Left: outlines of hydroelectric system)

Pic. 2 Outlines of the monitoringsystem

Pic. 3 View of a live camera throughsmartphoneⒸISERD77

IJERD – International Journal of Environmental and Rural Development (2015) 6-2

Considering those conditions, an electric bulb and monitoring system with water level sensor andlive view camera was installed. Through the monitoring system, water managers could check the waterlevel of their irrigation ponds and also watch the conditions of water intake and its surroundings
through a computer or smart phone if the internet connection was available. A monitoring system wasinstalled at Yanaka irrigation pond, which had a water level sensor and live view camera. Users could
check the water level and view of the irrigation pond through the internet connection. The system
required 200W for its operation.
Pictures 1, 2, and 3, show the electric bulb, monitoring system, and the view of irrigation pond
through smart phone, respectively.
CONCLUSION
Hydropower potential using irrigation pond was estimated. Estimated electric power output andelectric power were different at the ponds with similar storage capacity due to different watermanagement. Field experiment of siphon intake generation was also conducted and constant power
output was generated. Using hydroelectric power to support the operation and maintenance of a farm
pond, replacing manpower and fuel with electricity, would be one of the best ways to generate electricity
at a farm pond.
ACKNOWLEDGEMENTS
The authors gratefully acknowledge financial support from “Community Contribution SupportActivities”, Tottori University and technical supports from Tottori Institute of Industrial Technologyand Asahi Organic Chemical Industry Co. Ltd.
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