Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
INTRODUCTION................................................................Pages 1-3
HYDROLOGY OF THE TONLE SAP REGION........................Pages 4-5
TOWNS SURROUNDING THE TONLE SAP LAKE................Pages 6-7
MOUNTAINS SURROUNDING THE TONLE SAP LAKE........Pages 8-9
TRIBUTARIES OF THE TONLESAP LAKE.............................Pages 10-12
CONCLUSION....................................................................Pages 13-14
REFERNCES.......................................................................Pages 15-17
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
INTRODUCTION
Professionals such as doctors and nurses have made it very clear what they can do to help, we know
what teachers can do to help, but for the disadvantaged people which constitute the communities
living on and around the Tonle Sap Lake in Cambodia, what can we, as Professional Engineers do to
help? It is our obligation to sustain the expansion and growth of these communities (Refer to Figure
1). It is that which is our profession, to think of ideas and solutions to solve the many problems and
concerns experienced by any person, group of people or community alike, in this case those
surrounding the Tonle Sap Lake, and then to ultimately outlive these solutions.
“Amongst the greatest challenges we face in the world today are those of delivering growing, secure
and affordable supplies of clean water and energy to meet the needs of an expanding population,
whilst reducing our CO2 emissions and the human contribution to climate change. The
implementation of innovative engineering solutions is fundamental to addressing these challenges.”
– Professor Julia E. King. Chair of the Educating Engineers for the 21st Century Working Party.
In concurrence with the views expressed by Professor Julia E. King, providing clean and
inexpensive supplies of energy is a key consideration for the Tonle Sap communities. The fact that in
rural areas of Cambodia, only 9% of households have access to electricity and that they pay some of
largest prices in Asia (US $0.35-0.9kWh) (World Bank (2003), Renewable Electricity Action Plan
(REAP)) gives reason to believe that providing environmentally friendly solutions to Cambodia’s lack
of energy supply is a desperate area for investigation.
The Tonle Sap Lake basin takes up around 80000km2 ( Live & Learn Environmental Education
(2007)), and is fed by many tributaries, the main river which flows into the Tonle Sap being the
Mekong River via the Tonle Sap River. The Cardamom Mountains lie south east of the Tonle Sap Lake
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
and the Dangrek Mountains to the north, both of which have water (mainly from monsoonal rains)
which flow into surrounding rivers and by extension into the Tonle Sap Lake.
A vast majority of Cambodia’s energy supply is provided by wood and charcoal whilst the
rest comes from petroleum products, all of which produce unwanted and environmentally harmful
pollutants. Consideration of such energy issues in addition to the enormous amounts of water which
flow into and retreat from the Tonle Sap Lake each year, would naturally lead one to the idea of
Hydropower.
Thorough consideration of hydropower has led to the suggestion of a mini hydroelectric
generator. The core concept of this will involve the spinning of an axle in which copper wire is forced
to cut magnetic flux between two plates of magnets thereby inducing a current and producing
electrical energy and power. The driving force for rotation of this axle is that which has provoked
this particular investigation, water flow. In due course, this has motivated the questions of where
the water flow will come from and thus where the mini hydroelectric generators ought to be
located, whether or not the flow will have enough force to produce electrical energy, and in the case
that it is, how many people will it supply energy to?
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
Figure 1
(Sourced fromArchipelago, 2009)
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
HYDROLOGY OF THE TONLE SAP REGION
It is important to identify the main flow of water associated with the Tonle Sap Lake because this is
the foremost idea of whether there is enough flow to consider implementing a mini hydroelectric
generator.
Just like most countries which are within close proximity to the equator, Cambodia
experiences two distinct seasons, a dry season and a wet season. The dry season occurs from
November to May and during this time, water drains from the Tonle Sap Lake into the Tonle Sap
River until Phnom Penh, at which the Tonle Sap River diverts into the Mekong River (Refer to Figure
2). During this dry time of the year the equatorial low pressure system moves north and the region is
now predominantly influenced by the sub-tropical high pressure system, bringing cool dry air back
into the region. The total outflow of water from the region is 72.9×109 m3 per year (Kosal 1998).
In the wet season, the sub-tropical high pressure system moves south and the Tonle Sap
region is predominantly affected by the equatorial low pressure system which causes climatic
conditions to become hot and wet due to the hot humid air. In this time the Tonle Sap River which is
the main connection between the Mekong River and the Tonle Sap Lake, reverses its flow due to
monsoonal rains in the Mekong River (Refer to Figure 2). This massive excess of water flows from
the Mekong River into the Tonle Sap River and then into the Tonle Sap Lake. As a result the surface
area of the Tonle Sap Lake changes from 2500-3000 km2 to 10000-15000 km2 and the depth of the
lake increases from 1m to around 10 m (Wright, Moffatt, Wager, 2004). The flow into the Tonle Sap
Lake is estimated to be around 45×109 m3 per year (Kosal 1998).
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
Figure 2
(Seasonal variations in hydrology of the Mekong and Tonle Sap Rivers: Helsinki University of Technology)
This is of particular interest to the investigation because it addresses the question of where
the flow comes from. Since the Mekong River passes around 45×109 m3 of water per year (Kosal
1998) into the Tonle Sap Lake, it is evident that flow exists and that more detailed investigation will
reveal if it is possible to use such flow to generate electricity.
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
TOWNS SURROUNDING THE TONLE SAP LAKE
The main towns which surround the Tonle Sap Lake include Chong Khneas, Kampong Phluck,
Kampong Khleang, Moat Kla, Prek Kram, Kbul Toal and Prek Toal (Refer to figure 3). Siem Reap is one
of the largest towns near the Tonle Sap Lake and the Stung Siem Reap (river) meets the Tonle Sap
Lake at a floating village called Chong Khneas which has a population of around 3000 (Kosal 1998).
The flow of water into the lake from Siem Reap would make a significant difference if it were able to
generate electricity because the people which live in floating villages are of those who have access
to not a lot of electricity.
Prek Toal is another village located at the north west side of the Tonle Sap Lake and is of
great interest to the investigation. The Stung Sangkar (river) which receives water from the Stoeng
Mongkol Borei at the town of Bakprea, flows next to the Prek Toal Community. With 337 households
and a population of 2124 (there is a total of 934 households and 5493 people living along the Stung
Sangkar between Prek Toal and the Tonle Sap Lake) (Source: Ear-Dupuy, et al, 1997, Sourced by
Kosal 1998), being able to supply electricity for these people is of high interest.
Kampong Phluck is located on the north east side of the lake and has around 440 families
(2800 people) (Wright 2004) and whilst it would be worth while providing electricity for this
community, the fact that the river which connects this village to the Tonle Sap Lake is not very wide
nor has much flow suggests that this is perhaps an implausible idea.
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
MOUNTAINS AROUND THE TONLE SAP
It is well known all over the world that mountains provide outstanding water flow whether it be
from melt water or merely from rainfall. Upon research of Cambodia’s geography (and as previously
mentioned), it is evident that to the south east of the Tonle Sap Lake lies the Cardamom Mountains,
which has a highest peak of 1771m (Refer to Figure 4). On the east side of these mountains, around
1500mm of rain falls each year (Library of Congress Country Studies 1999). With a distance of about
65km (measured on Google Maps) between the base of the Cardamom Mountains and the nearest
edge of the Tonle Sap Lake, consideration of locating a hydroelectric generator for communities on
the lake there is simply unfeasible since it would require vast amounts of money and material to
transfer generated electricity the 65km back to the communities.
The Dangrek Mountains (Refer to Figure 4), whilst not as elevated as the Cardamom
Mountains, does receive more rain, estimated at around 1600-2000mm per year (Library of
Congress Country Studies 1999). However since the nearest base of the Dangrek Mountains to the
Tonle Sap Lake is almost double the distance of the Cardamom Mountains to the lake, it seems even
less plausible to locate a hydroelectric generator at the base of these mountains. For the intents and
purposes of this investigation, a conclusion has ultimately been reached that any water flow to be
used in this energy application will be that of the surrounding river systems and not run-off water
from the surrounding mountains.
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
TRIBUTARIES OF THE TONLE SAP
This leads to the discussion of the main tributaries of the Tonle Sap Lake. “Tributaries are the
capillaries of river systems” (North Cascades Glossary). The Tonle Sap Lake has several surrounding
tributaries and as a result receives a vast amount of water not only from the Mekong River but from
other water systems described in Table 1. Of course the chief tributary is the Mekong River which
liberates more than 475 km3 of water each year into the Tonle Sap River (Wright, Moffatt, Wager,
2004) via the Kratie hydrological system with an average of 13700 m3/s reaching the Tonle Sap Lake.
It is important to note however that this figure refers to the water dispensed through all of the rivers
which connect the Mekong River to the Tonle Sap Lake and not to a direct flow from the Mekong
into the lake. The next most prominent tributary is the Tonle Sap River itself, which has a maximum
and minimum flow of 2860 m3/s and 680 m3/s respectively into the Tonle Sap Lake (Wright, Moffatt,
Wager 2004).
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
The following table describes the many tributaries and their flow properties.
Table 1
RIVER
WATER FLOW INTO THE TONLE SAP LAKE (m3/s)
Stung Chinit
Stung Sen
Stung Stoung
Stung Chickreng
Stung Sreng
Stung Sisophen
Stung Borbo
Stung Mongkal Borey
Stung Krang Ponley
Stung Battambong
Stung Daontri
Stung Sangkar
Stung Pheas
Stung Svay
Stung Preah Neat Preah
Stung Kampong Krasaing
Stung Siem Reap
Stung Rolous
Preak Tunal Dack
Oleu
Stung Neang Sa Sngeh
Stung Sraka Moan
Stung Taing Krasaing
6711
11685
4486
4326
9732
6590
2876
6666
2943
5683
2826
5679
6590
3464
3724
1262
2902
2347
1838
1962
3388
3622
3384
(Figures compiled from information from CNMC, 2003, site in reference list)
With a modest flow rate, the Stung Chinit (highlighted in Table 1) seems appealing for the location of
the hydrological generator. It has a length of 264 km, a basin area of 4504 km2 and 1590mm of
rainfall each year. There is an increase in flow from June and rapid decrease in October. The actual
side profile elevation of the Chinit River (Figure 5) suggests that the speed of the water flow would
be increased due to a decrease in potential energy (or increase in kinetic energy) upon displacing
around 160m vertically down. The Chinit River system meets the Tonle Sap down near the Stung Sen
Biosphere Reserve core area which is a long way from any of the villages surrounding the Tonle Sap
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
Lake. So despite it being a good location in terms of water flow, its location is not ideal for delivering
power to people.
Figure 5
(Source from Unknown Author, available from http://flood.dpri.kyoto-u.ac.jp/ihp_rsc/riverCatalogue/Vol_02/02_Cambodia-2.pdf)
Whilst Table 1 suggests that the Stung Sen and Stung Sren would provide the biggest driving
force due to their very large water flow, their location relative to the Tonle Sap Lake is south east
and there are no major villages nearby. This eliminates any practical purposes of locating a
hydroelectric generator here.
Of all of the tributaries displayed in Table 1 it seems that the most appealing is the Stung
Sangkar River. It flows through several communities, the largest being Prek Toal, and it has a
relatively large flow rate.
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
CONCLUSION
The Stung Sangkar River (Figure 2) has an average flow of water into the Tonle Sap Lake of 5679 m3/s
(CNMC, 2003). This converts to a weight force of 55700kN which is sufficient for rotating the main
axle of the hydroelectric generator. As the specific design of the generator is still being developed, a
quantitative analysis of the amounts of electrical power this flow will be able to produce is yet to be
determined. With around 5493 people living alongside the river (Kosal 1998) between the village of
Prek Toal and the Tonle Sap Lake, the prosperity of the Stung Sangkar River for the location of the
mini hydroelectric generator is unmistakable, and for likewise reasons, as is optimising energy
production.
Prek Toal is made up of four villages. In the dry season the houses all line up along the
riverbanks and in the wet season when the water level rises above the level of the riverbanks, the
houses spread out on the lake. The income of the people in Prek Toal is variable, ranging from about
US $1 up to US $10 (Malin Meinander, Helsinki University of Technology). On the whole however,
the people of Prek Toal are relatively poor, so whilst the hydroelectric generator will do much good
for the community it may also pose solutions other than providing electricity. If the people able to
gain an basic education of how the generator works, they could use it as a form of livelihood,
perhaps they might charge people to recharge their car batteries.
The other major consideration which must be made here is the fact that the water level rises
so much in the wet season, so the generator will have to be designed in some kind of unit that is
ultimately portable. Methods of directing flow into the generator are currently being developed but
what is certain is that in places such as Prek Toal where the water level rises above the original level
of the houses in the wet season, the method used to direct flow to the generator will have to be able
to return to its natural state once inhibited by water.
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
For reasons discussed previously, the location for the hydroelectric generator(s) will be
located along the Stung Sangkar River (Figure 6), at Prek Toal which is near to where the river meets
the Tonle Sap Lake.
Figure 6
(Stung Sangkar River at Prek Toal; Photo by Malin Meiander)
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
MAIN REFERENCES

Engineers Without Borders Australia, 2009, Tonle Sap 09 Living on the Water (Design Brief). Available from: <www.ewb.org.au/ewbchallenge>. [6th
August 2009]

World Bank, 2003, Renewable Electricity Action Plan (REAP), Cambodia. Available from: <www.reacambodia.org>. [8th August 2009]

Map of the Tonle Sap Lake, 2006. Available from: <http://www.cambodia-map.com/map_pdf_TonleSap-map.png>. [8th August 2009]

Map of the Tonle Sap River and Mekong River and Tonle Sap Lake. Available from: <www.osmosetonlesap.net/en/tonle_sap_lake.html>. [8th August
2009]

Cambodia Topography, 2008. Available from: <http://countrystudies.us/cambodia/36.htm>. [7th August 2009]

Cambodia: Climate and Weather 2009, tourism travel guide, Cambodia Travel Guides. Available from:
<http://www.canbypublications.com/cambodia/climate.htm>. [8th August 2009]

Ritter, Michael E. The Physical Environment: an Introduction to Physical Geography,
2009, Tropical Monsoon Climate. Available from:
<http://www.uwsp.edu/gEo/faculty/ritter/geog101/textbook/climate_systems/tropical_monsoon_1.html > [8th August 2009]

Unknown Author, Stung Chinit. Available from <http://flood.dpri.kyoto-u.ac.jp/ihp_rsc/riverCatalogue/Vol_02/02_Cambodia-2.pdf>. [10th August
2009]

Lamberts, D. Part 1: Tonle Sap Ecosystem, 2001, Case Study. Available from <http://www.fao.org/docrep/004/ab561e/ab561e06.htm#bm06.1>
[10th August 2009]
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis

Tonle Sap, Cambodia 2008, Traveljournals.net. Available from: <http://www.traveljournals.net/explore/cambodia/map/m1527461/tonle_sap.html
>. [10th August 2009]

Cambodia 2009, world atlas, WorldAtlas.com. Available from: <http://www.worldatlas.com/webimage/countrys/asia/kh.htm>. [11th August 2009]

Geography of Cambodia, 2007. Available from: <http://motherearthtravel.com/cambodia/geography.htm> . [12th August 2009]

North Cascades Glossary. Available from: <http://www.nps.gov/archive/noca/glossary.htm>. [14th August 2009]

CNMC, 2003, Tributaries of the Tonle Sap Lake. Available from: < http://www.wepa-db.net/policies/state/cambodia/river2_2_4.htm>. [14th August
2009]

May, A (ed.) 2005, A Student’s Guide to the 2006 Geography TEE, Geographical Association of Western Australia.

Live & Learn Environmental Education (2007), Tonle Sap Information Guide, Phnom Penh, Cambodia.

Dr. Geoff Wright, Dr. David Moffatt, Dr. Jonathon Wager, March 2004, Establishment of the Tonle Sap Basin Management Organization, Cambodia
National Mekong Committee. Available from: <http://www.adb.org/Projects/Tonle_Sap/tonle-sap-basin-profile.pdf> [14th August 2009]

Mr Kosal, Mam, 1998, Social Implication of Conservation of the Designated "Prek Toal" Core Area of the Tonle Sap Biosphere, Reserve, cambodia
UNESCO-MAB Young Scientists Research Award Report. Available from: <http://www.unesco.org/mab/doc/mys/98/kosal/kosalrep.pdf>. [15th
August 2009]

Malin Meinander, 2009, Livelihood Sustainablilty Analysis of the Floating Villages of the Tonle Sap Lake, Cambodia, Helsinki University of
Technology. Available from: <http://civil.tkk.fi/fi/tutkimus/vesitalous/opinnaytteet/meinander2009.pdf>. [15th August 2009]
Introduction to Professional Engineering Group 27
Investigative Report: Location of Hydroelectric Generator
Todd Dennis
IMAGE REFERENCES

TravelBlog Travel Guide, 2009. Available from: <http://www.travelblog.org/Travel-Guide/>. [15th August 2009]

Canby publications, 2009. Available from: < http://www.canbypublications.com/maps/srtonlesapmap.htm>

Unknown Author, Stung Chinit. Available from <http://flood.dpri.kyoto-u.ac.jp/ihp_rsc/riverCatalogue/Vol_02/02_Cambodia-2.pdf>. [10th August
2009]

Malin Meinander, 2009, Livelihood Sustainablilty Analysis of the Floating Villages of the Tonle Sap Lake, Cambodia, Helsinki University of
Technology. Available from: <http://civil.tkk.fi/fi/tutkimus/vesitalous/opinnaytteet/meinander2009.pdf>. [15th August 2009]

Google Maps. Available from: <www.maps.google.com.au>. [August 16th 2009]