This is lesson 6 of IKS taught to Master level students on Indigenous Irrigation Systems at the Faculty of Agriculture, Rajarata University of Sri Lanka

1. Indigenous Knowledge Systems
lesson 6 - Indigenous Irrigation systems (cascade system,
water harvesting concepts) (2hrs)
• P.B. Dharmasena
• 0777 - 613234, 0717 – 613234
• dharmasenapb@ymail.com , dharmasenapb@gmail.com
• Links to publications:
https://independent.academia.edu/PunchiBandageDharmasena
https://www.researchgate.net/profile/Punchi_Bandage_Dharmasena/contribu
tions
http://www.slideshare.net/DharmasenaPb
https://www.youtube.com/channel/UC_PFqwl0OqsrxH1wTm_jZeg
• Course Code: MS 5208 (02:30/00)
• Saturday 3.30 pm – 5.30 pm (ZOOM)

2. Indigenous Knowledge Systems
2. Fundamental features of Sri Lankan Agriculture; climate, Soil, Genetic
resources, agro biodiversity (2 hrs)
3. History and the culture of Sri Lankan agriculture sector development (1 hr)
4. Green revolution and its impact on Sri Lankan traditional agricultural
system (biodiversity deterioration, inorganic substances for pest and disease
controlling, development of hybrid varieties etc.) (1hr)
5. Indigenous soil management practices (2hrs)
6. Indigenous Irrigation systems (cascade system, water harvesting
concepts) (2hrs)
9. Traditional practices for, weather forecasting, plant nutrient supplementing,
pest and disease control and indigenous agricultural machines and tools (2hrs)
13. Cultural dimensions of Agricultural rituals in Sri Lanka (1 hr)
14. Climate change and Indigenous Agricultural knowledge in Sri Lanka(1 hr)
Total: 12 hours)
List of lectures by P.B. Dharmasena

3. Indigenous Water Resources Management – not only
for Irrigation
Water resources management was of multi-
purpose:
• Food production – irrigation;
• Human needs – settlement, drinking
water, bathing, recreation, other domestic
needs;
• Rainwater harvesting systems;
• Existence of the environment (flora,
fauna, environs);
• City planning (Anuradhapura, Sigiriya)
• Parks, landscaping etc. (water springs,
ponds)
• Administrative boundaries
• Natural disaster mitigation (Flood,
drought, cyclone, epidemics)

4. Indigenous Irrigation Systems
Master Plan of Sri Lanka
River basin level
Inter-river basin level
Inter-reservoir level
Sub-watershed level
Village level
Field level

5. Prince Vijaya (543–505 BC) invaded our country
• Sailors entered the country from Alli
Rani Harbour for trading
• Vijaya also came along Western
coastal boarder using NE monsoonal
winds passing Alli Rani Harbour to
Kudiramalai (Thammenna)
• There were 10 regional kings
(including the Prince Kuweni ) ruled
the country at that time
• Prince Vijaya killed most of them with
the support of Prince Kuweni
• That was the end of 10 kingdoms of
Sri Lanka
Alli Rani Harbour
Kudiramalai

6. Kevesastha (Northern)
Upulwangiri (Kala Oya)
Rakungiri (Malwathu Oya)
Mahagiri (Samanala mountain
area) – Kelani, Kalu, Walawe,
Mahaweli
Chalaka (Mi Oya)
Neelagiri (Modaragam Aru) Kawasthalabha (Yan oya)
Dhumaka Kaddeera (Deduru Oya) Indra (Maduru Oya,
Mundeni Aru, Gal oya)
Agni (Kumbukkan Oya,
Menik Ganga, Kirindi Oya
River Basin Level Water Governance (3,000 BC)

7. Sharing water resources in the past
(600 BC – 1200 AD)
• Dambulu Oya -
Malwathu Oya
diversion canal (860
AD)
• Malwathu Oya -
Kanadara Oya diversion
canal (860 AD)
• Yoda Ela - Nachchduwa
feeder canal (540 AD)
Mahakanadarawa
Nachchaduwa
Kalawewa-
Balaluwewa
Dambulu
oya
Malwathu
oya
Kanadara
oya
Kala Oya
Inter-river basin level

8. Manewa cascade
Mahakanumulla cascade
• Single bank canal
• It runs along contour
• Water is collected from upstream
• Water is released to both sides
• Canal moves along tank upstream
• Tank cascade systems are fed
Kalawewa-Thisawewa Giant Canal
Inter-river basin level

9. – Kalawewa - Thisawewa Yodha
Ela (470 AD)
– Nachchaduwa - Nuwarawewa
feeder canal (290 AD)
– Balaluwewa -
Siyambalangamuwa feeder
canal (290 AD)
– Basawakkulama - Maha
Vilachchiya feeder canal (470
AD) Kalawewa-Balaluwewa
Thisawewa
Siyambalangamuwa
Nachchaduwa
Nuwarawewa
Mahavilachchiya
Basawakkulama
Malwathu
oya
Thalawa
oya
Kala oya
Sharing water resources in the past
(600 BC – 1200 AD)
Inter-reservoir level

10. Anicuts to divert water in Deduruoya Basin
Stone anicuts (Ex. Sukara Nijjara Amuna)

11. Anicuts to divert water in Deduruoya Basin
Timber anicuts (Ex. Kotta Badda Amuna) – King Parakramabahu-1

12. Sukara Nijjara Amuna – King Parakramabahu-1

16. Thekkama Amuna –
Malwathuoya by King
Dhatusena (459-477 AD)

17. How did they
locate ancient
reservoirs?
Kantale
Huruluwewa
Minneriya
Giritale
Parakrama Samudra
Maduruoya
Mapakadawewa
Udawalawa
Kalawewa &
Balaluwewa
150 m
contour

18. Network of tanks
and streams
No flood and no
drought

19. Nachchaduwa
Kanadarawewa
Vilachchiya
Kalawewa and
Balaluwewa
Huruluwewa
Main factors:
1. Morphology (landscape)
• Lower elevation,
• Moderate undulation
2. Rainfall
• Bimodality
• ~1500 mm/ year
3. Soil and geology
• Regolith aquifers
• Low infiltration
• RBE – LHG
Network of tanks and streams in the form of cascades

20. Tank clusters or cascades

21. Tank clusters or cascades

22. Tank clusters or cascades

23. Distribution of tank
cascades in Sri Lanka

24. Tank cascades
are found in:
Northern;
North Central;
North Western;
Uva; and
Southern
Provinces

25. Tank cascades
are found in:
Mullaitivu;
Vavuniya;
Anuradhapura;
Trincomalee;
Puttalam;
Kurunegala;
Hambantota;
and
Monaragala

26. Tank cascades
are found at the
elevation range
of 100-500m
amsl

28. DL 1b DL 1e
DL 1f
DL 1c
DL 1b
DL 5
Agro-ecological regions:
DL 1b, DL 1d, DL 1e, DL 1f, DL 5
DL 1d

29. North and North
Central cascade
Zone and North
Western cascade
Zone are located in
the Wanni Complex
South and South
Eastern Cascade
Zone is located in
the Vijayan
Complex

30. Tank cascades
are found mainly
on RBE and
LHG soils and
some on RYP
and IBL

31. Tank cascades
are found mainly
between 800 –
2000 mm
isohyets of
annual rainfall

32. Tank clusters or cascades
• A ‘cascade’ is a connected series of tanks organized within a micro-
catchment (meso catchment) of the dry zone landscape, storing,
conveying and utilizing water from an ephemeral rivulet’. (Madduma
Bandara, 1985)

33. Cascade defines surface water movement
alone
• Cascade ecology (Ecology is the study of the interactions of
living organisms with one another and with their physical
environment).
• Land (extent covered by cascade catchment)
• land use (specific land use systems with natural and
agricultural land uses and commons),
• Soil properties (changed soil properties due to
cultivation, water table and groundwater movement),
• Flora (different floral communities and ecosystems),
• Fauna (different faunal communities and ecosystems),
• Groundwater (water table fluctuation and groundwater
movement with chain of surface storages),
• Human activities

34. New definition of the tank
cascade system
• An ecosystem, where water
and land resources are
organized within the micro-
catchments of the dry zone
landscape, providing basic
needs to human, floral and
faunal communities through
water, soil, air and vegetation
with human intervention on
sustainable basis’
– Dharmasena, 2019

35. Evolution ofTraditional Settlements

36. Tank-village
Tank-village
Olagam tank
Kuluwewa
Kuluwewa
Kuluwewa
Kayanwewa Kayanwewa

37. ATraditional Settlement

38. Traditional Agricultural Practices in adaptation to
climate change
• ‘Bethma’ practice during drought periods
• It is a practice that temporarily redistributes plots of land among
shareholders (paddy landowners) in part of the command area
(territory) of a tank (reservoir) during drought periods
• ‘Pangu’ method – Regular maintenance to avoid disasters
• The tank had to be maintained properly to avoid breach, leak, and
excess seepage. Repair and desiltation of tanks and cleaning of canals
during dry periods are shared tasks assigned to each farmer
proportionately to land ownership.
• ‘Kekulama’ if the low rainfall maha is expected
• Farmers advance the cultivation time using early seasonal rains
whenever they feel that tanks would not get enough water to cultivate
the command area. They have the experience that if September (2nd
inter-monsoonal) rains are high, the total seasonal rainfall is not
adequate to fill the tank.
• ‘Thawalu Govithena’ during extremely dry situation
• Tank bed cultivation using little rains constructing a main soil bund
between deep phase and shallow phase of the tank bed

39. Four strata of tank water body
Madakaluwa – dead storage area
Wewpitiya – deep water area
Waangilma – area between FSL and HFL
Wewthaula – shallow water area
Master bund in Thawulu Govithena to
prevent tank sedimentation

40. Waangilma
Wewthaula
Wewpitiya
Madakaluwa
sluice
Four strata of tank water body

42. Diyaketa pahana - Alishthana

43. ‘Karahan kote’ for distribution of irrigation water
Q1 for
A1
Q2 for
A2
Q3 for
A3
Q = Q1 + Q2 + Q3

44. Giritale Tank - the ancient sluice to which the controlling
gateway under the water surface still remains lost

45. Uru Sita Wewa

46. Rambakan Oya Old Irrigation Canal

47. An interlocking joint of the granite ruins of the ancient
sluice gate

50. Yan Oya pre-historic burial site

51. Ibbankatuwa pre-historic burial site
Sri Lanka has a recorded history since 543 B.C. Although records are not
found of civilizations before 543 B.C., historical facts reveal that a
civilization existed even long before from Rawana Times.
It's believed that an Expelled prince Vijaya to be the first Aryan King of
Sri Lanka. Since then many Kings Ruled Sri Lanka Till 1815.

52. Ancient Sluices
1
2
3
6th century BC
3rd century
BC
459 – 477 AD

55. The spill ways
Source : “ Ancient Ceylon”, H. Parker, 1910”

56. The village tank sluices
Source : “Wewa, U.B. Awesadahamy, 2003”

57. Ridee Bandille
• A system of diverting water from perennial water stream
without building a dam across the water way.

58. Ancient Rainwater Harvesting
Technology
Fountains
Vertical flows
Vertical flows

60. 1 km

63. Sigiriya kings
must had been
in need of clean
drinking water

64. Three water
conveyance systems
• Open water
conveyance canals
• Sealed subsurface
clay pipes
• Sealed subterranean
conveyance canal

65. Octagonal
pond
Water garden 1 – Interconnected garden
complex for bathing
Water garden 2 – Fountain gardens
Water garden 3 - Royal water palaces
surrounded by moats
Water
garden 3
From Western
Entrance

66. Altitude at the lowest point of
Pidurangala rock top: 324 m
Altitude at the water spring
point of Sigiriya: 198 m
Elevation difference: 126 m
Direct Distance: 1225 m
Smooth slope path
distance:1612 m

67. Elevations:
Sigiriya tank: 204 m
Fountain garden: 204 m
Octagonal pond: 212 m
Head difference: 8m (26 ft)
Atapattam Pokuna:
212 m
Fountain ponds
204 m
Octagonal pond relatively at
a higher level

69. Evidence of a
huge explosion
Not a natural
decay

70. Rainwater flow
pitch (convex)

81. Balancing Stone

82. So called
balancing
stone

83. Finally ….
The platform area of Pidurangala rock is about 2 ha. If it is
assumed that 80% of monthly rainfall could be collected from
this flow pitch, the volume, which could be stored monthly
is:
Months Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Total
Rainfall
(mm) at
75%
probability
30.3 12.6 26.0 87.7 31.8 3.1 3.4 4.4 25.9 132.
0
168.3 105.7 631.2
Runoff (m3) 485 202 416 1,403 509 50 54 70 414 2,112 2,693 1,691 10,099

84. • According calculations at least 10,000 m3 of water
can be collected from this system.
• What does it mean?
• This historical perception can be rejected as a myth.
• However, this system if rehabilitated will supply
annual water storage of 10,000 m3 to the people,
who are living around and are threatened with the
chronic renal disease with unknown aetiology.
Then …..

85. • If the daily drinking water requirement is 3
lits./head, the problem of annual drinking
water requirement of 9,000 people can easily
be solved

86. Indigenous Water Resources Management – not only
for Irrigation
Water resources management was of multi-
purpose:
• Food production – irrigation;
• Human needs – settlement, drinking
water, bathing, recreation, other domestic
needs;
• Rainwater harvesting systems;
• Existence of the environment (flora,
fauna, environs);
• City planning (Anuradhapura, Sigiriya)
• Parks, landscaping etc. (water springs,
ponds)
• Administrative boundaries
• Natural disaster mitigation (Flood,
drought, cyclone, epidemics)