A Special Lecture has been delivered for Students at the Faculty of Agriculture, Rajarata University of Sri Lanka on the course - Traditional Technology in Sri Lankan Agriculture on 26th July 2021

1. Special Lecture delivered
for Students at the Faculty
of Agriculture, Rajarata
University of Sri Lanka
P.B. Dharmasena
26th July 2021

2. COVID – 19 PANDEMIC
SITUATION
 Up to 26th July 2021:
 Cases: 194,801,209
 Deaths: 4,174,867
 Recovered: 176,749,905
Country Per cent
recovered
USA 83.8
UK 78.1
Russia 89.6
India 97.3
Sri Lanka 90.2
Bhutan 90.1
Nepal 94.6
Food habits
Environment
• Reasons for the death of Covid-19
victims
• Low immunity
• High blood pressure
• Diabetics
• Heart diseases
• Respiratory diseases

3. Human health can be ensured by improving the ecosystem health
Risk reduction impact

4. ANCIENT WATER RESOURCES MANAGEMENT MASTER
PLAN
Country level
Inter-river basin level
Inter-reservoir level
Sub-watershed level
Village level
Field
level

5. 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
Decentralized Governance
Leadership

6. Water resources shared by river basin leaders
(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)
Mahakanadar
awa
Nachchadu
wa
Kalawewa-
Balaluwewa
Dambulu
oya
Malwathu
oya
Kanadara
oya
Kala Oya
Inter-river basin level

7. 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
• Diyakaliya and wewa to ensure
water security
Kalawewa-Thisawewa Giant Canal

8. Left bank
Sedimentation
Diyakaliya
Natural
rock
Soil
mound
Mahailluppal
lama
Amunuk
ole
Diyakaliya
Source: Dr. Ashoka Karunaratne, 2021

9. Upper land and Lower land sluice
gates of Yodha Ela
Position of Upper land
Sluice gates
Position of lower land
Sluice gates
B
A
Aluth
wewa
Amunukole
wewa
Koon
wewa
Wewa
Source: Dr. Ashoka Karunaratne, 2021

10. Diyakaliya Wewa
1 Placed above the canal Placed below the canal
2 Canal has been connected to
the diyakaliya
Constructed the canal running above
the wewa
3 Diyakaliya has been
connected to a natural rock
line or soil ridge
Bund of the wewa has been raised to a
higher contour
4 Issue of water through a
natural process
Release of water to wewa is through
sluice placed on the left bank of Yodha
Ela canal
5 Controlling the Sediment Controlling the sediment and
providing water to paddy tract
6 Providing water to upland
cultivation
Combined with human settlement and
cascade systems
Source: Dr. Ashoka Karunaratne, 2021

11. April – May
2010
“Inconvenient Truth” behind
Engineering Designs of
Irrigation Projects
developed during the Last
Century.
“……….Those days we
thought that the canal was
planned to avoid rock
barriers as the ancient
people did not own the
technology to break them
……..”
- Eng. Mahinda
Panapitiya

12. – 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
Thisawe
wa
Siyambalangamu
wa
Nachchadu
wa
Nuwarawe
wa
Mahavilachchiya
Basawakkulama
Malwathu
oya
Thalawa
oya
Kala oya
Water resources shared by reservoir leaders
(600 BC – 1200 AD)

13. Tank Cascade Systems – Collective
Leadership (Self governing system)
රාල leadership
• ගමරාල - Village leader
• කපුරාල - Leading rituals
• දනුමැතිරාල - Knowledgeable person
• වෙදරාල - Medical practitioner
• නැකැත්රාල - Providing auspicious times
• (සිෙුරාල) - Religious knowledge

14. Self governing system with 10
commandments
1) Èhm;a;dhï ;yxÑh – Regulations for water
security during drought
2) kshu lkafkg f.dú;eka n;a – Correct time of
cultivation to reduce the risk
3) .yfld, i;diSmdjd ìxlf¾ j;=rhs wdhsfndajd –
Use of environment without destroying it
4) wdlfya jeyslefgka jeõ wuqkq mqfrdamka – Harvest
rainwater and store for future use
5) ysf;a biamdiqjg oxmsx lrkakg meámia mrdfka
yodmka jvdmka – Make your mind free to attend
religious events through raising 5 types of
babies

15. 5 types of babies - meámia mrdfka
Child
Calf Kitten
Pup
Chick

16. 6) tl;=mdod fkdù yßyuka jevla
fkdlrka – Work as a team
7) ù l=ryka iïndf¾ wgqfldgq
mqrjka rdf,a – Store excess
grains for future use
8) f;,a meKs we;akka lejqïo
m[a[x – What is impossible if
everything is with you?
9) flï myka oek.ka ikqyf¾
/l.ka – Gain knowledge to
protect all
10) lú isxÿ rd.ka ys;g ldjoaodmka
– Preserve the cultural arts
Self governing system with 10
commandments

17. Sanitary places of
women and kids
Sanitary places of men
Faeces as a nutrient source to paddy fields
Tank-village system has been declared now as a
Globally Important Agriculture Heritage System (GIAHS) by UN
A Self sustained System based on precise management of water

18. Searching for a Globally Important Agricultural Heritage System
(GIAHS)

19. The first GIAHS declared in Sri Lanka by UNFAO on 19th
April 2018 is the Cascaded Tank-Village System and it is the
39th in the World.
Globally Important Agricultural Heritage System
(GIAHS)

20. • ‘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
Water sharing and water recycling

21. Water sharing and water recycling
Water is recycled through
• Drainage from paddy fields (welpahuwathura)
• Tank seepage into common drainage (kiul ela)
• Lateral flow of groundwater supplying water
to puranawela

22. Productivity Potential of Tank Cascade System
• Physical productivity potential:
• food, water, air, timber, fuel wood, medicine, raw materials
for handicraft, …..
• Economic productivity potential:
• agriculture, fishery, livestock, handicraft, ………..
• Ecological productivity potential:
• habitats, biodiversity, aesthetic beauty, nutrient cycling,
…………..
• Scio-cultural productivity potential:
• living environment, local knowledge, tourism, education,
human health, rituals, ……………..

23. Challenges in water resources
management
• Low and uneven
distribution of
rainfall
• Landscape
• Some reservoirs
did not have
adequate
catchment
• Sedimentation
of canals -
Diyakali

24. Prince Vijaya (543–505 BC) invaded our
country
• Sailors (merchants) entered the country from
Alli Rani Harbour for trading
• Yodhawewa and 162 small tanks were
constructed to produce rice to feed the sailers
• 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
Yodhawewa

27. ARUVI ARU (MALWATHU OYA) SUB BASINS

28. 

   


   
 

1
2
3 4 6
5

7
Army
Restaurant
Main Road
New NWS&DB well field
Giant Tank
Overhead Tank
Currently
Pumping
Wells
Irrigation
Canal
Boutique
WRB
BH
Sirikulama
Area


Shallow Test wells
Existing Tube Wells
Sandy
Alluv
ium
Clay Alluvium
Anuradhapura
Fault Zone

10
N

8
9

29. GROUNDWATER RESOURCES IN SRI LANKA
 Deep confined miocene limestone aquifers – North
West Sri Lanka – Puttalam, Mannar, Mulaitivu districts
Geologic cross section across the Murunkan basin

30. 6
Lithology of confined miocene limestone aquifer
Soil and clay rich alluvial (0 – 2m)
Alluvial sand layer (2 – 8m)
Miocene Limestone (11 - 50m)
Fresh rock (> 50m)
Clay layer(8 – 9m)
Sand layer(9 – 10m)

34. 505 MCM
100 MCM
605 MCM
184
MCM
101
MCM
256
MCM
6
MCM
250
MCM
64
MCM
Paddy
Water supply
314 MCM lost
to sea
Natural
vegetation
Diversion
GIANT’S TANK BASIN WATER BALANCE
30%
17%
11%
1% 41%

35. Objectives of Traditional Soil Management
1. Tillage – Objective is to obtain a
weed free smooth soil surface for
germination and initial growth
First tillage is taking place under
water mixing all weeds and
incorporating green leaves he added.
After about two weeks he ploughs
again and prepare the land syrupy
enough for sowing. The traditional
farmer uses betel spit to test the soil
condition for sowing. Betel spit
Objective of traditional soil
management was to increase
physical, chemical and biological
fertility of soil

36. Traditional Ploughing Techniques – Sinhala
Nagula (plough), Poruwa (leveller) • Formation of
hard pan at 4-6”
depth
• Rice root system
within 6” is
more active
• Water is not
percolated due to
hard pan
• Nutrient is not
lost from the
root zone
• Weeds with tap
root are not
comfortable

37. Lewis - 1884
Handle
නගුල් කඳ
Gripping peg
පළු ඇවේ
Blade
හී ෙැල
Trailer
නගුල් ඉහ
Balancing log
වකාවෙක්
වකාවේ
Components of Sinhala Nagula

38. Rice soil
Mechanism of Sinhala Nagula
Clay hard pan
4-6”
Plough
Farmer is competent to
operate the plough without
piercing the hard pan with
the shape of plough handle

39. Objectives of Traditional Soil Management (contd…)
2. Soil conservation -
Erosion control and
sustenance of soil fertility
Construction of dykes –
Cleaning dykes and
plastering to prevent weed
germination
On individual farms,
cultural practices and
agronomic practices are
adopted to conserve soil.
Mostly emphasis is on
reducing erosion in channels
and streams, tank bunds and
on reducing sedimentstion
on reservoirs

40. Liyadda – Bench terrace
•Soil erosion control is achieved by terracing the
land, especially in the rice cultivation

41. Traditional Vision of Water Management
Integrated Water Management Approach (Rainwater,
Irrigation water, Groundwater)
Saturated soil
zone
Capillary action
Water
table
fluctuation
Poorly drained
soil
IWRM

42. Gal bami (Stone bund) and Neththikanu
(Leader drains)
• Stone ridges are
constructed with rubble
available in the land
itself
• Leader drains are to
carry water down the
slope without subjecting
the soil for erosion.
These are made of
rubble without using
any cement

43. Green manure application to paddy fields
• Thespesia populnea (ගංස෕රිය)
• Erythrina variegata (එරබදු)

44. Green manure application to paddy fields
• Hibiscus tiliaceus (පටබෙලි)
•
• Pongamia pinnata (කරඳ)

45. Green manure application to paddy fields
• Tithonia diversifolia
(නත්තස෕රිය)
• Azadirachta indica (වකාවහාඹ)

46. Traditional Soil Fertility Management
Practices in Paddy Fields
• Follow period
• Planting trees on
paddy fields
• Utilization of
nutrients in irrigation
water
• Green manuring and
animal waste
• Aquaculture in
paddy fields

47. Fallow period
• Fallow periods add nutrients to the
soil, depending on their length.
• If farmers cultivate only during one
season; paddy field is left fallow over
8 months.
• If they cultivate two seasons ; still the
field is left fallow for about 5
months.
• In addition, some parts of the paddy
fields are left fallow for years due to
various reasons.
• Most farmers own more than one plot
in the village paddy tract, but cultivate
only the best plots, leaving others for
use when there is sufficient rains.
• In some cases, lack of capital and
labour may cause some plots to be left
fallow.
• Because of scarcity of water, some
farmers cultivate only the areas
farthest below the tank during the
maha season and only the upper
portion close to the tank during the
yala season.

48. Fallow period
• During the fallow period,
farmers encourage the growth
of leguminous weeds on paddy
fields. For example, some of
the common weeds grown on
the fallow paddy fields are:
• Cassia tora (Pethi thora),
• Tephrosia purpurea (Pila),
• Mimosa pudica (Nidikumba).
• Besides, during the fallow
period, buffaloes and cattle are
allowed to graze on the fallow
paddy fields. Hence, a large
volume of dung and urine is
accumulated on the paddy
fields, enhancing its fertility.
• The long fallow period also
permit the remaining paddy
residues and other vegetative
matter to decay, adding
organic matter to the paddy
soil.

49. Planting trees on paddy fields
• It is traditional among the
farmers in the dry zone to
plant perennial trees on their
paddy fields.
• They planted 4 to 5 trees per
acre. Even today, sparsely
grown trees are a major
characteristic of the paddy
fields in traditional villages.
• The purpose of planting
trees on paddy fields was to
provide shade during
relaxation and during meals.
Women used to keep their
children under these trees
when they worked in paddy
fields.
• These trees also contributed
to the fertility of paddy
fields.

50. Planting trees on paddy fields
• The best example is
Madhuca longifolia or Mee
tree
• Even today the Mee tree is
a common sight in old
paddy fields. It is
interesting to note that
fruits of the Mee are eaten
by fruit bats. They
congregate on Mee trees
when fruits are ripe and
their nitrogen rich
droppings are an important
source of fertilizer.
• The leaves of these trees
are also rich in nitrogen, so
the accumulation of leaves
on the paddy fields further
increases the fertility of
soils.

51. Utilization of nutrients in irrigation water
• Since the upper catchment area around the paddy tract was
covered with forest, the water runoff and leachate from the
forest was rich in nutrients.
• The forest runoff brought suspended fertile silt and soluble plant
nutrients to the paddy fields, renewing soil fertility each year.
• Of the several nutrients found in irrigation water, those present
in relatively large quantities are potassium (K), calcium (Ca),
magnesium (Mg), sulphur (S), and silicon (Si).
• Some of the silt carried by the forest runoff was carried directly
to the paddy tract, while the rest was deposited at the bottom of
the tank. Once in several years, farmers used to remove the tank
silt and added it to the paddy tract.
• Furthermore, during the periods when the tank dried up, the
mud-sluice (the sluice in the lowest location) directed a lot of silt
to the paddy tract.
• It is also said that the traditional farmers used to utilize the
nitrogen from the rainwater. They believed that the first rains
(Akvessa) contained nitrogen. Therefore, in order to gain the
advantage of the nitrogen in the first rains, they used to sow the
paddy before the first rains.

52. Green manuring and animal wastes
• Green manures have been
added to the paddy fields for
many years.
• Some of the common
species used as green
manure for paddy fields
were:
• Croton lacciferus
(Keppitiya),
• Tephrosia purpurea
(Pila),
• Cassia occidenialis
(Penitora),
• Aleurites triloba
(Telkekuna), and
• Azadirachta indica
(Kohomba).

53. Green manuring and animal wastes
• Traditional paddy cultivars had long stems, so in the
past there was much more straw to return to the field
than today with short stem cultivars.
• Since almost all farmers had their own cattle and
buffaloes, there was ample supply of manure.
Farmers allow them to graze the paddy fields
• However, no evidence exists to prove any direct
application of manure to the paddy fields, but wastes
accumulated on the uplands around the paddy tract
were washed away to the paddy tract, enhancing its
fertility.
• Waste washed into paddy fields from Landa,
thisbambe, gangoda, gaala (cattleshed) contributes to
enhance the fertility of paddy fields

54. Aquaculture in Paddy Fields
• It has been traditional among the paddy farmers
to keep paddy fields flooded during the early
stage of the growing season to eradicate weeds.
This practice, in turn encouraged the breeding
of fish in paddy fields, providing valuable
protein at little additional cost.
• Fish colonized the paddy fields at the beginning
of the rainy season, then got trapped in the
pools when the water began to recede at the
onset of the harvest.
• Fish were caught by bailing water out of pools.
Some species which survive in the paddy fields
become adapted to the drought conditions. For
instance, the air breathing fish:
• Anabas testudinius (Kavaiya),
• Ophiocephalus spp. (Lula, Mada Kanaya),
• Clarias teysmanni (Magura), and
• Heteropneustes fossilis (Hunga)
These species can survive conditions of
severe drought.

55. Aquaculture in Paddy Fields
• Fish that lived in the flooded paddy
fields benefitted the paddy crop in
various ways. While the carnivorous
species helped to control harmful
insects and worms, the herbivorous
species consumed algae and weeds,
leaving more space and nutrients for
paddy.
• Furthermore, they improved soil
aeration and increased the rate of
mineralization by disturbing the
bottom, and provided fertilizer
through release of excrement
• All contributed to increasing the
productivity of paddy fields. It has
been shown that fish in flooded paddy
fields increase the paddy harvest by
as much as 15%

56. • Chena cultivation
• Sharing land based on
productivity
• Burning the vegetation to obtain
high biomass, ash and debris
• Mixed cropping
• Paddy cultivation
• Shallow tillage – water and
nutrient conservation
• Drainage – dispose of polluted
water
• Varietal selection – duration,
medicinal value, season, water
logging, salinity
Nutrient conservation and adaptability to
nutrient status

57. TRADITIONAL SHALLOW TILLAGE
• Formation of
hard pan at 4-6”
depth
• Rice root system
within 6” is
more active
• Water is not
percolated due to
hard pan
• Nutrient is not
lost from the
root zone
• Weeds with tap
root are not
comfortable
Lewis - 1884

58. • Chena cultivation
• lands after cultivation are left out for years. Land productivity is rejuvenated to
make the crop pest and disease resistant
• Paddy fields
• Kurulupaluwa – Attraction of birds for the paddy field and allow eat insects
• Maintenance of rice – weed ratio for pest management (small plots)
• Village commons – Habitats for predators
• Forest tanks are left out for wild life to keep them away from farm fields
PEST AND DISEASE CONTROL

59. Therefore, I suggest it is essential to probe deeply the awakening of „Sri
Lankan Water Culture‟ not only through a physical/ engineering point of
view but also on the basis of a spiritual dimension.
When we attempt to study the creations made by a human society
nurtured in a spiritual environs by using only physical and environmental
principles we may understand only a fraction of it.

60. Tank-Village Ecosystem
Source:
Dharmasena, 2010

61. Godawala
Perahana
Gasgommana
Iswetiya
Tank water – no pollution, no sedimentation: safe drinking water,
good storage
Tank-Village Ecosystem

62. Landa
Thisbambe
Gangoda
Kattakaduwa
Kiul-ela
Paddy field - no salinity, good fertility: High productivity
Tank-Village Ecosystem

63. Gasgommana
Perahana
Rootlet web
Rootlet web
Rootlet web
Terminalia
arjuna

64. Pandanus
tectorious

65. Kattakaduwa encroached

66. Salinity
Development

67. Keta sorowwa – release surface water, self controlled
Traditional
sluice
Traditional Vision of Water Management

68. Diya keta pahana to measure tank
water level
Traditional sluice
Traditional Vision of Water Management

69. Karahan kote
Cuts are made in the log with different width and depth so that discharge
is different. This provides water for different extents and different soils
during the same sluice opening time
Flow distribution structure

70. • ‘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.
• ‘Thawulu 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
• ‘Goda wee hena’ due to inadequate tank storage
– Paddy and vegetables are grown on imperfectly drained soil with available soil moisture
Water sharing and water recycling