i

Ecosystem based indigenous water management

ii

Dedicated to God “Kadawara”

(According to the Sinhalese tradition, King Dhatusena appointed a man named Kadawara to maintain the magnificent Kalawewa. One day there was a breach in the bund. In order to stop the breach, Kadawara placed himself in the breach until workers repair it. During the event, Kadawara died and became a god. Today Kadawara is considered to be guarding the reservoir as a god as he did while he was alive.)

iii

Preface This is a valuable and timely publication on a vitally important topic, at a critical time. Apart from the problem of micro water management for cultivation mostly of traditional rice - paddy, there is the issue of macro water management, water sharing, in many parts of the country. After the on-going conflict over ‘traditional homelands’ is resolved, an even more serious and difficult conflict over water may follow. The seeds of the conflict over water were sown many decades ago, as I have documented over the past four decades, from the mid and later 1960s when I was working at Uda Walawe. To write this Preface, I referred to the Sanmugam Arumugam Commemoration volume ‘Water for People and Nature’, compiled by the late Engineer S H C de Silva, sometime Additional Director-General of Irrigation, and other Irrigation engineers in 2003. Both the Preface by Dr Ray Wijewardena titled ‘Water and Soil Conservation Ecosystems of Sri Lanka’, and the Introduction by Dr C G Weeramantry titled ‘The Significance of Sri Lanka’s Ancient Water Conservation Ecosystems to Modern Environmental Law’ are most appropriate to the subject of “Ecosystem based indigenous water management”, and extracts from those two chapters are used here with the authors’ permission. Dr Ray Wijewardena wrote that he was of the opinion that:

“By referring to the subject as ‘Irrigation’ we were perpetuating a rather serious misnomer; one which has probably crippled the country for decades. My suggestion was that the appropriate title was Water Conservation, rather than Irrigation”.

Mr Arumugam was one of the few engineers in his time who appreciated water conservation as well as small tanks, whereas most others had condemned them as ‘inefficient’ (from a hydraulic engineering perspective). Dr Ray Wijewardena offered a comprehensive explanation for this, and in effect described ‘ecosystem based indigenous water management’ from his own personal experience:

“The British engineers before us may be forgiven for their misunderstanding and mis-appreciation of the true purpose and function of the small tanks, which were strategically distributed throughout the countryside of this humid-tropical nation, on account of its unique climatic characteristics of alternating heavy rainfall and severe drought….

“As one who has farmed for many years in our ‘dry zone’, - and later served with several of the International Agricultural Research Institutes - it came to my understanding that these tanks, and almost all of those in southern India, demonstrated a major component of some of the finest systems of water conservation ever developed... That they had been designed towards achieving that fragile objective of sustainability which factor had, by subsequent and similar misunderstanding, likewise eluded many major civilizations in centuries gone by…..

“The run-off retained by the small tanks, strategically positioned across each fold in the contour, thus provided stability to an otherwise fluctuating water-table in the single monsoon regions of the dry zone where they were located. They are, likewise but more sparsely, evident in the two-monsoon regions of the wet-zone, where reasonably careful management of soil-cover, could provide the infiltration necessary to hold water in the soil and sub-soil until the next rains. (Regrettably this practice too has been all but lost in the mistaken fervour to emulate - as dry farming - the open-field farming systems of the west!).

“In the single monsoon season of the dry zone however, a sustainable existence was just not possible without a stabilised water-table to support the dry-zone forest garden and tree-based farming of the sloping ‘haena’, and supplementary rice farming of the ‘purana

iv

vela’. This, latter, was wisely restricted to the LHG - Low Humic Gley - soils which have very low permeability. Further conservation of the rainfall was achieved in bunded fields, now flooded to help manage weeds. (Let us remember that rice is a temperate and introduced crop which has, however, adapted well to the vela in the tropics, but which has proven colossally wasteful of now critical water, when also farmed thus on the RBE - Reddish-Brown Earth – soils”.

“The small tank system was always a key component in the water-conservation systems of our heritage…. They were not sources for abuse and mis-management under the misnomer of ‘irrigation’..... They were complementary to the system of interconnected large reservoirs and channels in the ancient Rajarata”.

Judge Weeramantry, former Vice President of the World Court, The Hague, said:

“The Water Heritage of Sri Lanka is a topic of worldwide interest, which has not attracted the attention and research it deserves. I therefore welcome any attempt to further our understanding of this system, which informed opinion regards as one of the most sophisticated irrigation systems the world has seen.

“Scholars of the greatest eminence, such as Arnold Toynbee in his monumental Study of History, Joseph Needham in his path-breaking Science and Civilization in China, and Arthur C Clarke in his inspired visions of the role of technology in uplifting the human condition, have all spoken of this system as the summit of global excellence in this field. It has also been described in superlative terms by such varied observers as Andrew Carnegie and Emerson Tennent, Henry Parker and R L Brohier, while recent work on the irrigation systems of the world, such as Goldsmith and Hildyard’s Social and Environmental Effects of Large Dams, recall how foreign observers have marvelled at it …..

“I have endeavoured in the legal field to stress the value of the wisdom and experience to be gathered in this field from past experience in maintaining a balance between these two essential considerations - development and environmental protection - which both exert enormous pressure, tugging the planner and the practical engineer in opposite directions.

“Out of this conflict has arisen the concept of sustainable development which I have sought to advance in the field of international law in several of my judicial opinions. In particular, in the Gabcikovo - Nagymaros Project case between Hungary and Slovakia in relation to the harnessing of the waters of the Danube, I stressed this concept and sought to elevate it to the level of a binding principle of customary international law. I believe it is now accepted as such.

“In urging for it this special legal status, I drew attention to various irrigation systems across the world and to the irrigation system of Sri Lanka as an example par excellence of a scheme which substantially advanced the concept of development, and at the same time substantially protected the integrity of the environment.

“I stressed in that Opinion, the immense, but much neglected, value of ancient wisdom to modern law --- a wisdom which placed great emphasis on the harmony between humans and their environment, on the rights of future generations and on concepts of communal duty rather than individual rights. I am glad to see that these trends have been picked up at various centres such as McGill University’s Center for Sustainable Development, and are being actively developed and advanced through academic and practical studies.

“The topic of sustainable development has in fact assumed such importance that it was the subject of a summit of World Heads of State and of World Chief Justices held at Johannesburg in August 2002. In my keynote address to the Chief Justices, I stressed the value of ancient wisdom, citing again the example of Sri Lanka’s water heritage as an outstanding example of this wisdom.

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“What strikes me as being of particular importance in this field of study is the perception that our ancient irrigation system was not merely an achievement of technical engineering skills of a pre-eminent nature, but also of a holistic conception of the setting of that expertise within the framework of an overall ecosystem of water and soil conservation. One cannot lose sight of either of these fields of expertise in which our forefathers excelled”.

These authoritative statements by two eminent scholars, Dr Ray Wijewardena the engineer - scientist, and Dr C G Weeramantry the scientist – jurist, is a great encouragement to the three authors of this original publication, Kapila Peiris, Mahinsasa Narayana and Sanjeeva Wijesinghe. They have taken on the ‘conventional wisdom’ of western educated and western oriented irrigation engineers, who as John Kenneth Galbraith once said are constrained to follow the conventional wisdom of the establishment, whatever commonsense, or traditional wisdom, or even their consciences may say. There is tremendous scope to build on this modest beginning. This little book has only touched the tip of the iceberg as the saying goes. It should be translated into Sinhala and Tamil, without delay, and made available to farmers at grass roots level. There will then surely be a massive feedback in support of what has been documented. Others will also take courage to contribute to the cause of restoring our cultural and economic heritage on the lines outlined in this original study. There is no time to be lost. D L O Mendis

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Content

Page 1. Introduction

2. Background

3. Indigenous water management

4. Concepts, attitudes related to the sustainable-development

model (for ecosystems)

5. Structural features and practices of this ecosystem

6. Comparison of water management methods

7. Paddy cultivation and water management

8. Evolution and Development of Irrigation Eco-Systems in

Ancient Sri Lanka

9. Conclusions / Comments

10. References

11. Appendix I

12. Appendix II

1

1. Introduction

The main objective of this book is to give a basic introduction about our indigenous water

management. Actually it can be described as ecosystem management. In this regard physical

structures, practices as well as cultural aspects (concepts, attitudes economic development

model etc) related to this ecosystem management will be briefly outlined.

Indigenous water-ecosystem management cannot be simplified only to its physical structures

and practices. Presently, the physical structures and practices are taken isolated from the

cultural aspects and then with the current governing economic development model, these have

little meaning. Therefore the intention of this little book is to introduce both of these aspects

of indigenous water ecosystem management in a holistic manner, and to come up with some

guidelines drawn from the “indigenous water ecosystem management” which could be

included in a current water policy or in a related manner to solve some of the problems related

to water (ecosystem) in today’s context.

2. Background

Sri Lankan history is deeply connected with its hydraulic civilization. Today this hydraulic

system is erroneously named as an irrigation system. Nevertheless according to most of the

authorities and scholars1 in this field this was a sustainable water – soil – flora - fauna – human

ecosystem, which was mainly based on2 inter-related reservoirs (small and medium scale tanks

(wewa)) and channels in Rajarata, vetiyas in Ruhuna, and on diversion anicuts (amuna) in

Mayarata (i.e. mainly the wet zone). The history of this ecosystem leads back to the 4th century

B.C. or earlier. Basawakkulama sometimes known as “Abhayawewa” was identified as the

most ancient Wewa, which was built by king Pandukabhaya.

Ancient kings had built major tanks and village tanks simultaneously. For an example king

Parakramabahu the great had constructed 165 dams, 3910 canals, 163 major tanks and 2376

village tanks during the last lap of Rajarata3.

The stability and sustainability of this ecosystem was due to its ability to store the water from

rainfall within the system for the benefit of the whole system. Unlike in modern irrigation

systems, which are focused on supplying the crop water requirement for the root-zone (zone in

soil where the roots of trees and plants are spread, water is absorbed by roots in this region), the

ancient so-called “hydraulic system” was focused on the water requirement of the entire

1 Eng. D L O Mendis, Dr Ray Wijewardena, Judge Dr C G Weeramantry 2 R L Brohier, 1934 3 S Arumugam, 1969

2

ecosystem. To fulfil this requirement, various types of structures such as major tanks, small

tanks, vetiyas, amunas, vila (lake), wala (pond) etc. (Figure 1) and inter connecting canals were

constructed very much in harmony with nature.

In some areas water from major rivers was conveyed to the major tanks and from there to the

small tanks and then to the fields, for example Elahera – Parakkrama Sagaraya. In some other

areas this happened the other way round, i.e. water spilling out from small-tanks was stored in

major tanks; for example Kuluwewas, small surface storage consisting of earth bunds used as a

silt trap, and flow controller for flood mitigation, raising the water table in the vicinity, were

incorporated in most of the ancient systems. In almost all these cases small tanks were

constructed in a cascade system, which facilitated efficient re-use of water. In this manner

these structures were used to store water in the ecosystem (i.e. in the soil and vegetation) in

drought periods, and were used in flood mitigation in rainy periods. It should be mentioned here

that irrigation was only a part of this hydraulic system, which should be seen as a conservation

system or more correctly as a water and soil conservation ecosystem. Kalaweva – Jayaganga is

often thought to be the classic example where large reservoir, trans-basin canal, and cascades of

small village tanks formed a stable human-made ecosystem.

As mentioned earlier, the heart of this ecosystem was the wewa, which gave the lifeblood for

the ecosystem. These systems have been sustained for thousands of years. The sustainability

and stability of these ecosystems is not only due to their physical structures mentioned earlier.

The culture that prevailed in these regions also provided necessary conditions for this

sustainability. As Pffafenberger said4: “a more useful definition of trechnology would certainly

include cultural values and social behaviour”. This culture can be assumed to be driven not by

the self-interest motivated by greed, but by other motivations like group interest (discussed

under 5.0 Water distribution), and sharing resources equally (even among animals, birds etc.)

and the equity of ownership. Arahat Mahinda when he preached the first sermon on sustainable

development at Mihintale in 223 BC5 stated that the king was only the guardian of nature and

not the owner. Keeping a Kurulupaluwa (portion of paddy field reserved for birds, that exists to

this day) was a direct outcome of this concept. This culture with the concept that we are just

guardians of nature, and the physical structures like wewa served this ecosystem, made it

possible for it to function for thousands of years. Thus this culture-ecosystem had the in-built

development model that is suitable for our environment and culture. Now we are going away

4 Pffafenberger, 1990 5 Judge C G Weeramantry (1997) Separate Opinion in the Danube dam case in the World Court, The Hague

3

from this tradition. Today we do not have an idea about our former development model and

therefore we cannot rehabilitate these ecosystems in a sustainable manner.

This has been observed by Judge Dr C G Weeramantry former Vice-President of the World

Court, The Hague, and by Judge Dr A R B Amerasinghe6 in the Supreme Court of Sri Lanka.

Judge Weeramantry said:7 “our ancient irrigation system was not merely an achievement of

technical engineering skills of a pre-eminent nature, but also of a holistic conception of the

setting of that expertise within the framework of an overall ecosystem of water and soil

conservation”. Justice Amerasinghe8 said “The Jayaganga …. is not merely a water course or

transportation canal corridor, or even an amazing technological feat as Professor K M de Silva

describes it; it is also an integral part of a human-made water and soil conservation ecosystem”.

It should be mentioned here that although we cannot go back to the same system today, the

guiding principles provide important guidelines for a modern day sustainable water

management policy.

3. Indigenous water management

In the ancient cultural context water management was not taken as an isolated issue. Here the

main objective of water management is to optimize the conditions for the proper function of the

human – made ecosystem in harmony with nature. Water was mainly stored in the wevas and in

the soil and conveyed through the soil, and the soil facilitated mainly the water purification

process. Water is taken from the soil (from the water table) then the used water is again

returned to the soil, which purifies the water and replenishes the water table for re-use. Water

was thus conserved in the soil, maintaining the water table. To facilitate this conservation,

physical structures like cascade wewa system in Rajarata, vetiyas in southern area, and amunas

were built according to the geophysical nature of the location. In this manner water received

from the two monsoons was re-used several times before it ultimately drained to the sea. Even

the inter-monsoon rains (Akvehi) would have facilitated this re-use process (i.e. cyclicity). The

water evaporated from the wewas help to create convection rains (Akvehi)9. Hence evaporation

from wewas is not a real loss! Also these structures facilitated flood mitigation process in the

lower parts of the ecosystem in heavy rainy periods. In this context ecosystem is defined even

including the man and the objects and the accessories required by him for his livelihood10.

6 Dr A R B Amerasinghe. (2000) Eppawala FR case SC Application No. 884/99, 2 June 2000 7 Preface in Water for People and Nature, Sanmugam Arumugam Commemoration. 2003, Vishwa Lekha 8 Reference 6, Eppawala FR case Judgement. 9 Farmers in villagers such as Puleliya, say this by looking at the directional movements of the clouds. When the clouds are almost stationary, they identify the rains as Akvehi 10 E P Odum, (1982)

4

4. Concepts, attitudes related to the sustainable-development model (for ecosystems)

From the time of the first sermon at Mihintale by Arahant Mahinda to King Devanampriya

Tissa (c. 223 BC), Buddhism has significantly influenced the Sri Lankan life style (e.g.

attitudes, concepts). Some prominent Buddhist concepts are listed below.

1. Greed (Thanha) is the cause for sorrow Dukha. Therefore it should be mitigated11.

2. Happiness is the most important wealth. (“Santhutti paramang Dhanang”)12

3. Equity of ownership.

4. Attitude towards nature - nature does not belong to anybody. We are only a part of it and

we can use it in a sustainable manner for our survival without disturbing much its use by

the other partners. Statement of Arahant Mahinda.

5. Less selfish, holistic community based approach to optimise the ecosystem.

6. Holistic approach towards nature13

5. Structural features and practices of this ecosystem

5.1 Rain water trapping structures

In the ancient water management, the amount of rainfall (nowadays measured in “mm”) and the

intensity of rainfall (nowadays measured in “mm/day”) were deliberated.

Small structures like Vetiya capture the water from very low intensity rainfall. Small tanks

capture the water from much higher rainfall and major tanks capture water from even higher

rainfall14.

11 Buddhist Sutrapitake – Lord Buddha 12 Buddhist Sutrapitake – Lord Buddha 13 Dr P B Dharmasena, Deputy Director, Field Crops Research Institute, Maha Illupallama 14 Dr C R Panabokke (2001)

Figure 2: Vetiya in southern region (from Walawe Engineering surveys)

Wala (pond)

Wila (lake)

Wewa

Wetiya

Figure 1: Rainwater trapping structures

5

5.1.1 Wewa

There are about 12,000 working small tanks and anicuts in Sri Lanka which irrigate an extent of

about 185,000ha. This is 35% of the total irrigable area in the country. Small irrigation schemes

produce 191,000 metric tons annually accounting for 20% of the national irrigated rice

production15. Following are the essential components of a village tank (Figure 3).

Gasgommana – It is the upstream of the land strip located above the tank bed and water is

accumulated in Gasgommana only when the tank spills. Naturally grown large trees such as

Kumbuk, Nabada, Maila, Damba etc. and climbers such as Kaila, Elipaththa, Kakukeliya,

kalawel, bokalawel etc. are found in this area. The gasgommana acts as a wind barrier and at

the same time it helps to reduce evaporation from the tank and to lower the water temperature.

It gets closer to the bund from either side where roots of large trees make water cages creating

breeding and living places for some fish species. This strip of trees demarcates the territory

between human and wild animals.

Perahana – It is the meadow developed under gasgommana and filters the sediment flow

coming from the upstream chena lands.

Iswetiya or potawetiya – It is the soil ridge constructed in the upstream of the tank at either side

of the tank bund to prevent the eroded soil from upper land slopes from entering the tank.

Godawala – A manmade water hole to trap sediment and it provides water for wild animals.

This might be a strategy used to avoid man-animal conflict.

Kuluwewa – A small tank constructed above the relatively large reservoirs only to trap sediment

and not for irrigation purposes, as seen above Minneriya weva for example16. It provides the

water necessary for cattle and wild animals.

Tisbambe – It is a fertile land strip found around the settlement area (gangoda) and does not

belong to any body. Tree species such as mee, mango, coconut etc. are grown in scattered

manner. Mostly this area was used for sanitation purposes and it acts as the resting place of

buffaloes. Buffaloes were used as a protection mechanism from wild animals and malaria.

Kiul ela – This is the old natural stream utilized as the common drainage. Tree species such as

karanda, mee, mat grass, ikiri, vetakeya etc. and few rare small fish species are also found in

water holes along the kiul ela. Most importantly it removes salts and iron in polluted water and

improves condition of the drainage water from the paddy tract.

Kattakaduwa – This is a reserved land below the tank bund. It consists of three micro-climatic

environments: water hole; wetland; and dry upland, therefore, diverse vegetation is developed.

15 Agricultural implementation programme 1994 - 95 16 Udula Bandara Avusadahami, 2000. Weva

6

This land prevents salts and ferric ions entering into the paddy field. The water hole referred to

as ‘Yathuruwala’ minimizes bund seepage by raising the groundwater table. Villagers plant

vetakeya along the toe of the bund to strengthen stability of the bund. It appears to be the

village garden, where people utilize various parts of the vegetation for purposes such as fuel

wood, medicine, timber, fencing materials, household and farm implements, food, fruits,

vegetables etc17. Specifically they harvest raw materials from this vegetation for cottage

industries.

Figure 3: Essential components of a village tank (Dharmasena, 2000)

5.1.2 Cascade system

A connected series of tanks are organized within the micro catchments of the dry zone land

escape, for storing conveying and utilising water from an ephemeral rivulet (Madduma Bandara

1985).

Figure 4: Functional diagram of a cascade system (Dharmasena, 2000)

17 Dr P B Dharmasena, 2000.

Chena

Perahana

Godawala

Tank Iswetiya

Landa Paddy field

Kiulela thisbambe

gangoda

Chena

kattakaduwa

Gasgommanana

7

It is now clearly recognized that the large number (more than 15,000) of small tanks that are

distributed across the undulating landscape of the dry zone are not randomly located and

distributed as previously commonly perceived; rather they are found to occur in the form of

distinct cascades that are positioned within well defined small watersheds or meso-catchment

basins. A cascade of tanks is made up of 4 to 10 individual small tanks, with each tank having

its own micro-catchment, but where all the tanks are situated within a single meso-catchment

basin. These meso-catchment basins could vary in extent from 6 to10 sq.miles, with an

optimum value of about 8 sq. miles in the North Central Province region.

Figure 5: Schematic representation of small tank cascade (Panabokke, 2000)

A schematic representation of a typical small tank cascade system with a scale of 1:50,000 is

shown in Figure 5. The main elements to make up a cascade are namely; (a) the water shed

boundary of the meso-catchment, (b) the individual micro-catchment boundaries of the small

tanks, (c) the main central valley, (d) side valleys, (e) axis of the main valley, and (f) the

component small tanks as well as the irrigated rice lands as shown in the same diagram.

8

These small tanks form a series of successive water bodies along small water courses and are

called a “cascading system’’. The advantage of such a system is that excess water from a

reservoir along with the water used in its command area is captured by the next downstream

reservoir, and is thus put to use again in the command area of the second reservoir. This water

is thus continuously recycled. This system helps to surmount irregularly distributed rainfall,

non-availability of large catchment areas and the difficulty of constructing large reservoirs18.

In Rajarata these cascades are very much related to the topography of the underlying bedrock.

Most of the cascades are situated above the ‘basins’ in the bedrock, and this would have

minimized the ground water outflow from the system. In Ruhuna area the underlying bedrock

slopes towards the sea, and this would have been one main reason why there are very few

cascades of small tanks in the area. In Ruhuna a structure known as ‘vetiya’ (Fig. 2) is used to

conserve water in upper portion of the soil19.

5.2 Sharing outcomes of ecosystem but not raw resources

The outcomes of the ecosystems (paddy, other crops, water etc.), which are needed for the

human livelihood, are shared among the people in the ecosystem. The ecosystem does not

belong to or owned by anybody. The ecosystem is virtually not divided among people instead

outcomes are shared. Dividing the system for individual ownership beyond a limit will disturb

the system. “Bethma” and “Thattumaru” methods of cultivations are adopted to avoid this.

5.3 Bethma method of cultivation

In water scare situations, villagers get together and agree on an area, which could be cultivated

with the limited water available. Later, the harvest (paddy) is divided among them.

5.4 Thattumaru method

This method is adopted by villagers, when the fragmentation of lands makes it difficult to

cultivate in small individual units. When a villager has a small unit, he opts to forego the

cultivation of his unit giving the opportunity for another to cultivate a larger unit including his.

This makes the operational unit more viable. Each farmer gets his turn although not every

season.

5.5 Water distribution

Traditionally a holistic approach was used for water distribution in the irrigable area, according

to community or group interest, rather than individual self interest as seen in modern schemes. 18 Panabokke (2000) 19 Prabath Vitharana, Department of Agrarian Services

9

The colonial lawyer F A Hayley in his book on Kandyan Law wrote:

“The irrigating stream, passes from one allotment to another, arranged, when possible, in a

series of terraces, in each of which the supply and depth is regulated by low ridges and

blinds, temporarily breached or dammed as occasion may require. The regulation of this

supply, the formation of the enclosing ridges, the joint use of buffaloes for ploughing, and the

need of fencing against wild animals, necessitate community of action on the part of tenants

of adjoining lands …

“To produce a successful crop, organization is required, some panguwas needing, from the

nature of the soil or elevation, treatment different from the others. For this purpose, the

tenants appoint their own official, the vel vidane or irrigation headman ... .

“It will be convenient here to refer to the social and administrative organization: for while the

lord of the village, or the chief or headman, to whose control it was assigned, was primarily

responsible for good order, there existed side by side with community of property, a

community of responsibility, and a recognition of self-government by the village council in

the regulation of local affairs ". (Hayley, 1990, pages 261-266, Village Communities)

Thus, the indigenous method is a bottom-up system of water management while the modern

method is a top-down system (Fig. 6). This is specially important when considering devolution

of administrative authority from the Centre to the regions that is being discussed today.

Indigenous system Modern system (Source: Brohier, 1941) (Source: Irrigation department)

Fire 6: Water distribution

Figure 6: Water distribution methods (Mendis, 2002, p. xxii)

Each farmer (plot) has a supply and outlet (drainage) separately

Water was supplied to the field in a holistic manner drainage from upper fields are used in lower fields (re-use)

10

5.5.1 Bisokotuwa

Biskotuwa20 is a device invented by ancient engineers to control the outflow of water from

wewa with considerable heights (10-15m). As shown in Figures 7, 8, 9 below, the Bisokotuwa

consists of a tank, rectangular in plan, connected to the sluice barrel or conduit; in almost all the

cases the longer side of the rectangle is kept parallel to the bund. Little real evidence regarding

the gates of the Bisokotuwa has been found up to now, although Brohier mentions a stone gate

in a sluice at Mahavillachchiya. (Brohier 1934, Vol. II). Speculation about gates, which would

have been made out of wood and controlled by a system of levers, are mostly accepted in the

present day among scholars. With these speculations about gates, the function of the

Bisokotuwa could be explained as follows (Figure 7):

When it is required to release water from the wewa, gate A is opened gradually while B is kept

open at a particular opening (or gate B would not have existed); then the water level in the

Bisokotuwa will come to a height less than that of the water level in the wewa. Then water will

flow through the sluice to the outside canal driven by the head of water in the Bisokotuwa,

without subjecting the sluice barrel or conduit in the bund to high pressure as well as velocities

created directly from the head of water in the wewa. When stopping the water release from the

wewa, gate A is closed then water inside the Bisokotuwa will flow through the sluice barrel,

without creating any vacuum condition. In this manner the Bisokotuwa acts as a ‘surge’ tank,

but this is not simply a ‘surge’ tank; if this was only a surge tank such large cross-sections such

as 11x8 feet, 10x9 feet etc. are not needed.

5.5.2 Analysing Bisokotuwa as a Flow Regulator and a Meter Using Modern Hydraulics

Figure 7: Schematic diagram of Bisokotuwa

20 Parker, H (1908) “Sinhalese engineers invented the bisokotuwa in the 3rd century BC”.

Gates

Bisokotuwa

11

Applying Bernouli’s equation to Bisokotuwa :

from A to B

H-h = f1 (Q, a1) _______ (1)

from B to C

h = f2 (Q, a2) _______ (2)

Where

H = Height of water in vewa

h = Height of water in Bisokotuwa

Q = Water Flow Rate

a1 = Opening area of gate G1

a2 = Opening area of gate G2

From equation (2) it is clear that for a particular set of values of a2 and h, Q will have a fixed

value. Now, the Bisokotuwa can be calibrated by finding the Q values for various sets of a2

and h i.e. determining the two variable function “f2 now if we want to have some particular Q

value then we have to find the two values of a2 and h accordingly and open the gate “G2”.

Now open the gate “G1” such that the water level inside the Bisokotuwa will be equal to above

“h” value. Then the required water flow “Q” will take place. When the water level in the vewa

goes down “h” will also go down. Then by increasing the opening area of gate “G1” “h” could

be brought to the initial value i.e. the water flow rate from the vewa could be kept constant

independent of the height of the water level in the vewa (for a particular range). Also once the

Bisokotuwa is calibrated as stated said above it could be used to measure the flow rate, i.e.

when “h” and ‘a2” are known ‘Q” can be determined by calibration charts or graphs.

When water is going out from the wewa, the water first enters the Bisokotuwa, the head of

water entering it is decreased by allowing it to expand in it. Bisokotuwa is an effective

expansion tank. This may probably be the reason for laying out the Bisokotuwa so that its

longer side is parallel to the bund i.e perpendicular to the sluice barrel or conduit, the direction

of water flow. In the Bisokotuwa the flow (and pressure) of water issuing from wewas with

high heads are controlled by dissipating energy in the water by letting it expand in the

Bisokotuwa or rather by allowing the water coming in to the Bisokotuwa to impact with water

inside the Bisokotuwa, thereby releasing its energy by an ingenious non-destructive method.

For this to take place properly, the volume of water inside the Bisokotuwa is of critical

importance. The large cross section of the Bisokotuwa stated above will fulfil this

requirement. The Bisokotuwa was described as the fore-runner of the modern valve pit or valve

tower by Parker (Ancient Ceylon), but such large cross sections are meaningless if this was

12

only a valve-pit. In some wewas, for example Urusita wewa at Sooriyawewa, (Figure 8) water

enters the Bisokotuwa by one conduit (sluice barrel) at the bottom center and goes out by two

conduits from the bottom of the opposite wall. With this arrangement the effect of momentum

of inlet water on outlet water will be minimized, i.e the outflow will be very calm. Also

velocity of water in the outlets will be lower than that of the inlet. Higher velocity in the inlet

will increase energy loss; low velocity in the outlets will give a gentle flow, which will not be

harmful to the bund as well as to the downstream channel.

The Bisokotuwa is also used to change direction of water flows. One such example is seen at an

outlet in Parakrama Samudra (Figure 9). In this case, water enters the Bisokotuwa from one side

and leaves it from a side perpendicular to it. The forces required to divert the flow of water is

obtained from the water itself (inside the Bisokotuwa). Therefore, no such effects as erosion of

conduits can take place.

5.5.3 Planked arrangements inside a bisokotuwa

According to Professor R.A.L H. Gunawardena (‘The ancient sluice at Maduruoya reservoir’),

Bisokotuwa of another type also has existed. In this type wooden panels were used to control

the water (Figure 11). These wooden panels were inserted parallel to the bund in a structure

which had grooves. With the wooden panels the bisokotuwa is actually divided into two parts.

Figure. 9: Water diversion at Parakrama samudra (plan)

Figure.10: Water diversion Bisokotuwa at Parakrama Samudra

Figure. 8: Bisokotuwa at Urusita weva

13

The level of water in the upstream side of the Bisokotuwa will be almost the same as in the

wewa. When the uppermost panels are removed water will flow into the downstream side of

the bisokotuwa and will then flow through the sluice conduit in the bund very gently.

Figure 11. Sketch of planked arrangements inside bisokotuwa

In this method water outflow (volumetric flow rate) could be controlled very easily and

independently of the water level in the wewa. Also because only the uppermost panels are

removed (or inserted) forces involved in removing (or inserting) will be less due to low

pressure. This is very similar to a “ketasoruwwa” (Figures 12, 13). Also this is very similar to

the principle of a planked anicut. Even very recently (about 30 years ago) at Ratmalgahawewa

in Anuradhapura, wooden panels inside the bisokotuwa were used to control outflow of water.

5.5.4 Navigation in canals with the aid of locks

A similar technique had been used to facilitate navigation along waterways at different levels

in ancient times. Elahera – Minneriya canal was restored by Parakrama Bahu (1153 – 1186)

using locks despite 60 ft. difference in level between Elahera and Minneriya. He built

Parakrama Sagara by raising Elahera anicut built by Vasabha ( 65 – 109 AC), creating

Koththabadhdhanijjara, described by Geiger as the “reservoir whose flood escape was walled

up” and also as the “weir furnished with a reservoir” (Mendis, 2002). Parakrama Sagara, the

second “Sea of Parakrama” was discovered by three British surveyors in 1855, and their report

was published by Governor Sir Henry Ward, in his Minutes in 1867. (Brohier 1934, Vol. 1 pp.

Dam Vewa

Keta

Figure. 12: Keta sorrowwa

Figure. 13: Keta sorrowwa, Puleliya

Wooden planks GrooveDAM

WEVABISOKOTUWA

14

28-32) An ancient tamarind tree to which boats were anchored had been found, and the stump

of this tree is now the site of a small shrine on the Elahera canal bund. The Surveyors report

re-published by R L Broher was ignored by engineers when the Elahera canal was restored

during world war II, (Brohier, 1941) and also later when Moragahakande reservoir and the

NCP canal was proposed. (Mendis, 2002)

Figure 14: Ancient bisokotuwa at Maduruoya

5.5.5 Ancient bisokotuwa at Maduruoya

Ruins of a basement, which could be considered as a basement of a structure, which carried the

relevant grooves, is found at Maduru oya old sluice (Figure 14), which consists of an almost

rectangular dressed stone sluice barrel or conduit backed by brickwork and a triangular brick

arch above the conduit, and these bricks do not show any wear due to water flow (Figures 15).

Therefore it could be concluded that this upper part of the sluice was not used to convey water

instead it would have been a free passage to prevent water flowing in the sluice conduit below,

making contact with the bund. Due to this arrangement even when pressure inside the stone

sluice increased and water flowed through it was unlikely to seep into the bund.

Figure 15: Ancient sluice at Maduruoya

15

5.5.6 Karahana

This device provides an even more simple distribution method in the downstream irrigated area,

when compared with modern methods. Once a certain amount of water is released from the

wewa each and every plot will get an approximately equal amount of water. Nobody is needed

to regulate water from plot to plot.

Figure 18 -Water dividing devices (Karahana) used in channels in Pul Eliya

Karahana

21

22

.ll

lQQ+

=&

&21

11

.lllQQ

+=

&&

Figure 16: Schematic diagram showing the function of Karahana

Figure 17: Picture of the Karahana at Pul Eliya village (Leach, 1967)

16

5.6 “Rajakariya”

A community based maintenance methodology for the ecosystem. In this method, about 40 days

of each year villagers worked for the benefit of the whole community (ecosystem).

5.7 Trans-basin canals developed within the ecosystems

With a holistic approach, in-situ time tested irrigation and water supply projects developed

gradually. For example Kalaweva - Jaya Ganga ecosystem was described by Brohier (1937):

“The Jayaganga, indeed an ingenious memorial of ancient irrigation, which was undoubtedly

designed to serve as a combined irrigation and water supply canal, was not entirely dependent

on its feeder reservoir, Kalaweva, for the water it carried. The length of the bund between

Kalaweva and Anuradhapura intercepted all the drainage from the high ground to the east

which otherwise would have run to waste. Thus the Jayaganga adapted itself to a wide field of

irrigation by feeding little village tanks in each subsidiary valley, which lay below its bund.

Not infrequently it fed a chain of village tanks down these valleys the tank lower down

receiving overflow from the tank higher up on each chain".

Another example is Parakrama Sagaraya, which has been described thus:

“King Vasabha (65-109) built the Elahera anicut and canal in the first century; nearly three

centuries later King Mahasen (276-303) built the Minneriya weva at the tail end of the canal,

and probably started its extension beyond Minneriya. Later kings, up to Aggabodhi I, (575-

608) completed the extension, and Aggabodhi II (606 - 618) built the Gantalawa weva

(Kantale tank) at the tail end. Beyond Kantale Weva, channels led to Tambalakamam bay and

the sea at Trincomalee.

“This system functioned in the next nearly six centuries, until the reign of Parakrama Bahu

(1153-1186), who restored and greatly improved the system. This king raised the Elahera

anicut, and strengthened the first 24 miles of the canal from Elahera to Konduruweva, thus

creating the second Sea of Parakrama, or Parakrama Sagara, described in the Culavamsa as

Koththabadhdhanijjara. This Pali word was translated by Geiger in two different ways which

have the same meaning as it should namely ‘the weir furnished with a reservoir’, and ‘the

reservoir whose flood escape was walled up’ ". (Mendis (2002).

Actually these are not canals in the modern sense. They consist of earthworks (bunds), which

divert the free flow of water slightly in order to collect water from excess-water areas and then

distribute them to water-scarce areas as in the Jayaganga described by Brohier. Therefore it is not

quite correct to express the gradients of such “canals” in the context of modern channels which are

17

meant to convey water from one point to another as quickly as possible. In most cases these old

channels follow a gently falling contour, and have only a single bund equipped with spillways. In

fact, Parakrama Talaka, the third “Sea of Parakrama” may have been formed by accumulation of

water along part of the contour channel of the Kalaweva Jayaganga as described by Brohier.

5.8 Diverting water from rivers

When diverting water from rivers, ancient ‘engineer’ has never ‘silenced’ the river (McCully,

1996). i.e. the natural river flow has not been stopped totally, instead a part of water has been

diverted without seriously affecting the downstream side of the river and also without creating a

large reservoir. In most cases, these goals were achieved by constructing oblique dams or weirs

(In some cases temporary wooden dams or weirs). Also in some cases these dams or weirs were

not built totally across the river. When the weir is built obliquely it could transfer (overflow)

much water flow without increasing the height of water above the weir. Therefore oblique weirs

provide a method to divert a small amount of water flow without significantly increasing the

water level above the weir which will otherwise make a deep large reservoir.

In almost all the cases water has been diverted from regions where the silt accumulation is

lowest (i.e. in most cases from the outward side of a bend). In ancient times water from water

excess areas were first taken into the nearest water scarce areas, then the remainder to the

immediate next and so on. Therefore elevating water for higher levels was not required, as in

modern lift irrigation projects introduced by transfer of technology.

5.9 Using the behaviour of water to take levels

Most of the ancient water systems, which now appear to be very large, were not done in short

time intervals as today. Actually these have evolved in stages (e.g. Jaya Ganga and Parakkrama

Sagaraya, in ancient Rajarata). Hence it is quite reasonable to assume that level measurements

related to these works would have also been taken along with the work while observing the

natural flow of water. Anyway there would have been simple devices, which could be used for

taking level measurements. Such a simple wooden device is shown in Figure 20.

Figure 19: indigenous levelling devices

Wooden frame

The bottom plane and plane ABC are parallel. By poring water to this vessel it is possible to take levels

18

Even today if we consider the formation of paddy fields (especially in wet zone) one can

observe large areas of levelled paddy fields. This levelling is achieved by observing the free

water flow and carrying out earthwork accordingly. No instruments as such are used!

6. Comparison of water management methods

Comparison of water movement-circulation in a typical indigenous ecosystem and water

distribution-drainage system in a typical modern system is illustrated as follows (A proper study

has to be carried out for more details).

6.1 Indigenous (traditional) ecosystem

This is the Ecosystems perspective, which is based on the sustainable development of human

and environment within the context of Sri Lankan culture. Water received as rain is stored in

the ecosystem in a usable manner then used and re-used as drainage is again fed to the system

and reused several times. Cause and effect of this is as follows:

• Small water cycles through soil: Water cycle is connected with soil in local vicinity.

• Water purification is mainly done by the soil.

• Whole land area is irrigated together so that water is conserved, conveyed through the soil

or unlined canals.

• Evaporation (specially from wewa) facilitates local water cycles and gives rise to

convectional rain (Akvehi)

• People live along the cascade, thus facilitating reuse of water

6.2 Modern system

The modern system is based on the hydraulic engineering storage tank perspective. Water

gained from rain is stored in tanks, then used and excess is treated as drainage. Water cycle is

largely connected with the sea or other reservoirs, mainly through pipeline or concrete canals

(i.e. water supply and drainage).

• Water cycle is less connected with the soil, people and nature, in local vicinity

• Less water purification by the soil (pollution is also high)

• Less water re-use

Today with urbanization connection of water with soil is reduced. Individuals suck water from

wells (from water table) and store them in overhead tanks. These will deplete the water table

then in most areas the used water is send to sea through drains without much contact with the

soil. Therefore the cyclicity of water through soil is disturbed and this will give rise to water

shortages, in the region. Also for towns water is pumped from rivers and other sources, no reuse

as in a village wewa. Population is clustered in towns unlike in cascade irrigation systems.

19

Today in most development projects canals are constructed for irrigation purposes and separate

pipelines are laid for domestic purposes. In ancient systems irrigation as well as other purposes

were fulfilled by the same water system, with people very much closer to nature and with very

much less water pollution. In fact Mahamankadavala Piyarathana Thera of Galkande Purana

Maha Vihare, Eppawala, said that about 30 years ago they drank the water from the canals, but

now with introduction of chemicals the water system has been polluted and separate water

sources are needed for human consumption.

7. Paddy cultivation and water management

Paddy cultivation is highly connected with water management in Sri Lanka. Almost all the

recent irrigation development projects were aimed at supply water for paddy fields. Anyway it

must be mentioned here that the actual crop water requirement of paddy and the amount of

water used for paddy cultivation in conventional paddy cultivation systems (in paddy fields) are

different. Water in conventional paddy field systems caters for many requirements of the

ecosystem.

Specially wet zone paddy fields acts somewhat like small wewas. Rainfall water, which could

easily drain to sea, is stored in these fields. Also these acts as sponges during heavy rains and

are a buffer against erosion. They develop the water table in the vicinity providing water to the

ecosystem.

Figure. 20: This is not only irrigated paddy cultivation but also conserving water for the ecosystem

According to Dr. Ray Wijewardene, in the single monsoon season of the dry zone, a sustainable

existence was just not possible without a stabilised water-table to support the dry zone forest

garden and tree-based farming of the sloping “haena”, and supplementary rice-farming of the

“purana-vela”. This latter was wisely restricted to the LHG (Low Humic Gley) soils, which

have very low permeability. Further conservation of the rainfall was achieved in “bunded

fields”. Paddy, a plant, which could withstand flood condition was grown in these “wewas”.

20

Therefore one cannot directly say that all the water in paddy fields are a requirement of paddy,

and paddy is a crop, which “wastes” water. Proper studies have to be carried out on this matter,

based on the ecosystems perspective. To facilitate such study, contrasting features of the

hydraulic engineering and ecosystems perspectives are listed as follows (Mendis, 1986):

Hydraulic Engineering vs. Water and Soil Conservation Ecosystems Hydraulic engineering

(Hard technology/Transferred knowledge)Ecosystems perspective (Soft technology/Traditional knowledge

1. Water inanimate, active animate, passive

2. Small tank “inefficient” stage in evolutiondevelopment - to be replaced by large reservoir

micro-irrigation ecosystem - essential part of total complex of human-made ecosystems

3. Large reservoir “efficient” system in combination with channel distribution irrigation system

macro-irrigation ecosystem with micro-irrigation ecosystems in its command area

4. Diversion Channel built to augment a large reservoir - last stage in irrigated agriculture system

earliest stage in irrigated agriculture

and evolution of ecosystems

5. Vetiya “abandoned small tank” deflection structure - micro water and soil conservation ecosystem

6. Downstream development areas

must be cleared of all vegetation to lay out channel distribution irrigation systems

designed as a series of micro water and soil conservation ecosystems

7. Forest areas limited to catchment areas not only in catchment areas - inter- spersed with fields in development areas for better nutrient flows

It is worthwhile to quote the following on “rice paddy ecosystems” in Bali by Steve Lansing21

(1991) because it would be very helpful in understanding our ancient paddy ecosystem also.

“The role of water in rice paddy ecosystem goes for beyond providing water to the roots of

paddy plants. By controlling the flow of water into terraced fields, the farmers are able to

create pulses in several important cycles. The cycle of wet and dry phases alters soil pH;

include a cycle of aerobic and anaerobic conditions in the soil that determines activity of

micro-organisms, circulates micro-nutrients; fosters the growth of nitrogen- fixing cyan

bacteria; excludes weeds; stabilizes soil temperatures; and over the long term governs

formation of a plough pan that prevents nutrients from being leached into the subsoil. On a

larger scale the flooding and draining of blocks and terraces also has important effects on

pest populations. If farmers on adjacent fields can synchronize their cropping patterns over a

sufficiently large area, rice pests are temporarily developed of their habitat and pest

populations can be sharply reduced.” 21 Lansing. 1991

21

7. Evolutions and Development of Irrigation Eco-Systems in Ancient Sri Lanka

(Mendis, 1986)

1. Rain – fed agriculture

2. River diversion from a flowing river (ganga oya, ara etc.) Temporary or seasonal diversion structures made of sticks and stones etc. on poor foundations

3. Development of permanent river diversion structuresDevelopment of dressed stone masonry, including wedge shaped blocks, use of lime mortar etc. on good foundations

4. Construction and operation of spillways and weirs Along contour channels, using dressed stone masonry, natural rock ourcrops etc.

5. Invention of the sluice (sorowwa), with access tower (bisokotuwa) – precursor of the modern valve tower

6. Construction of small, medium and large storage reservoirs across non-perennial oyas and aras, and in so-called dry valleys, using the sorowwa with bisokotuwa for controlled issue of irrigation water, and the spillway for safe discharge of flood runoff

7. Damming a perennial river Two techniques were available for damming a river that had some flow, however small, even in the driest season:

i. Temporary river diversion through a sluice ii. The twin – tank method

Diversion channels for flood irrigation on riverbanks

Development of contour channels

22

Figure. 21: Temporary stick dam at Kalahagala - An example of stage 2 in above.

9. Conclusions / Comments

Water management cannot be identified as an isolated issue. It is intimately related to the

national economic development model related activities, physical structures, practices,

concepts, and attitudes in the related culture. A basic introduction about these interrelated

categories in modern and ancient contexts is given in this report. Therefore in addressing water

related issues one should base it on this threefold approach.

(a). Today in the process of solving the water shortage problems one should first study the

methods and ways of improving the cyclicity of water through nature separately for each

geophysical situation. Conserving water in soil must be considered first i.e. water table

should be uplifted. In “hydraulic” water works only rainfall data from isohyets and

topography of catchments are taken into consideration. Cyclicity of water through soil (as

well as through vegetation and atmosphere) is ignored. Evaporation from tanks (wewa)

and seepage are taken as losses!

Economic development model- related activities

Physical structures- practices

Concepts-attitudes in the related culture

23

Also instead of net rainfall, rainfall intensity (mm/day) has to be taken into account22.

Rainfall intensity has a direct bearing on the distribution of water in soil, therefore by

considering this fact proper structures such as Vetiya, wewa has to be constructed in order

to store water from rainfalls of varies intensities, in soil in an usable manner i.e. water

should be stored at low matric potentials as much as possible. When water is stored in soil

matrix it will be in a negative pressure relative to atmosphere. Surface water and water in

water table has zero matric pressure.

In water balancing calculations for an ecosystem (or for the whole country) one cannot say

that the total outflow from a ecosystem (or from the whole country through rivers etc)

through underground seepage or upland rivers could be used, or in other words that one

can stop these flows and use that water for other purposes, because this will disturb and

unbalance the ecosystem. Negative outcomes of the projects of damming perennial rivers

throughout the world are well documented23. Principles of indigenous water management

in Sri Lanka do not allow us to treat water after use for irrigation as total waste. Water

balance calculations should be done based on the ecosystems perspective i.e. by

considering the whole ecosystem, its activities functions etc. related to all of its flora and

fauna. Also it should be mentioned here that water used by any particular crop or

cultivation also should be determined according to this perspective. In this case we may

have to redefine the efficiency terms related to these aspects. Proper ecosystem based

studies have to be carried out.

(b). As mentioned in section 7, water management projects related to paddy cultivation should

be based on the ecosystem perspective instead of on the crop water requirement of the

paddy plant.

(c). Cultural practices such as Bethma method should be introduced wherever possible. Also

instead of considering only on paddy, ecosystem based chena cultivation and home garden

cultivation should also be promoted.

(d). The trend is that the decisions such as the amounts of water that should be allocated for

irrigation and hydropower generation are determined by the market price of paddy and

electricity. This however distorts the sustainability of the ecosystem. Therefore a proper

22 Dr James Handawela, Deputy Director of Irrigation 23 McCully, 1996

24

national based valuing system should be introduced for paddy, electricity etc in the

ecosystem perspective.

(e). Today most of the irrigation projects, which have not shown expected results like for

example Lunugamvehera and Udawalawe are based on large reservoirs identified from a

map described as the Water Resources Development Plan of Ceylon,1959 (Mendis, 2002).

This Plan does not identify (give proper value) to the ancient structures Wewa, Vetiya etc,

which facilitated water storage, purification and conveyance through soil. This map was

derived from the 1 mile to an inch topographical survey sheets, and 100-foot contours are

shown. The dams of these projects have been located too close to the sea thus reducing the

re-use of water. The proposed Moragahakanda project is also identified from this map.

(f). Projects selected from this map and based on a modern hydraulic-civil engineering

perspective are not concerned about our ecosystem based perspective which has been time

tested for thousands of years. There have been many adverse consequences.

(g). For example, in Lunugamvehera project about 12 small Wewas, which were within the

storage area, and 30 Wewas in the command area have been demolished. According to the

Village Headman of Lunugamvehera Mr Punchi Appuhami, prior to the project, before the

construction of the massive dam, all these interconnected wewas had functioned in a

typical ecosystem with the reusing of water. Almost all the necessary food items such as

jak, coconuts etc. were produced in this system. Now water in the Lunugamvehera tank is

not sufficient to feed the estimated command area and farmers are moving in to the

direction of cash crops, which require less water, such as banana. Therefore now the

ecosystem has degraded physically and culturally. In this context, it is strongly

recommended to conduct a scientific study in the ecosystem perspective to determine the

actual water usability (how much of water gained from rain is used to develop the

ecosystem in a sustainable manner), in Lunugamvehera and Udawalawe areas, before and

after the construction of the dams. The results of this kind of study will provide proper

guidelines for future planning of such costly projects.

(h). In addressing water problems at present most importantly we have to change our attitudes

about water and related aspects. Here we would like to quote from an article appearing in

Scientific American (Special Report 2005) “Making every drop count” by Peter H. Gleick.

“Part of the difficulty, however, also lies in the prevalence of old ideas among water

planners. Addressing the world’s basic water problems requires fundamental changes

in how we think about water, and such changes are coming slowly. Rather than trying

endlessly to find enough water to meet hazy projection in future desires, it is time to

25

find a way to meet our present and future need with the water that is already available,

while preserving the ecological cycles that are so integral to human well being”.

This attitude towards water and related aspect is very much closer to the above said

attitudes and concepts that prevail in the Sri Lanka culture.

(i). Ecosystems are not owned by anybody, humans are also an important part of the

ecosystem and they fulfilled their requirements within the development model, not going

against the sustainability of the system. This is a cyclic relationship. But in the modern

situation development is isolated from the ecosystem, and development proceeds apart

from the ecosystem. Only when the ecosystem inhibits the development the concept of

“sustainability of the ecosystem” comes to attention.

(j). Water is an integral part of the ecosystem therefore clearly it is also not owned by

anybody. Everybody could use it to fulfil their requirements within the sustainable limits

of the system. Therefore water cannot be priced and sold in a so-called “free” market.

Instead the State could get a tax from water users according to the amount of their water

usages. This tax is actually a contribution to the development of the ecosystem. If a person

uses water beyond his requirement he has to contribute in a proportional manner i.e. if

somebody uses water beyond his requirement he does it due to his ability to contribute

more to the system in a less selfish manner.

(k). Water is a scarce resource. But unlike a commodity such as fossil-fuel water is in a cycle,

and being chemically stable, water could be reused many times within the water cycle

without breaking the cycle. In ancient water management this reusing was mainly

facilitated by soil, vegetation and atmosphere. This was almost a natural “reuse”. The

concept of the King Parakramabahu the Great was to reuse the water received from rain as

many times as possible before it drained to the sea. Today the construction of massive

dams in order to block perennial rivers will certainly interrupt the water cycle and hence

the ecosystem will have negative results. Unlike in almost all the modern development

projects, which gives rise to negative environmental effects, the ancient wewa has had

positive environmental effects!

26

10. References

1. Amerasinghe A R B, Judgement in the Supreme Court Application No. 884 / 99 (FR) published in Mendis, D L O, Pugwash, Globalization and Eppawala – Pugwash Betrayed? Or Eppawala Betrayed? pages 90 – 150, (2000). Vishwa Lekha.

2. Arumugam S. Water Resources of Ceylon (1969) Water Resources Board

3. Sanmugam Arumugam Commemoration volume, Water for People and Nature (2003).

Vishwa Lekha.

4. Avusadahami, Udula Bandara, 2000. Weva.

5. Brohier R L, Ancient Irrigation Works in Ceylon 3 vols. (1934) Government press.

6. Brohier R L, “Inter-relation of Groups of Reservoirs and Channels in Ceylon”. Journal of the Royal Asiatic Society, Ceylon Branch. Vol. 34. No. 90 (1937).

7. Brohier R L, The history irrigation and agricultural colonization in Ceylon, The

Tamankaduwa District and the Elahera – Minneriya Canal. (1941), reprinted by Academy of Sri Lankan Culture 1998

8. Dharmasena P. B, “Towards efficient utilization of surface and ground water resources

in food production under small tank system”, Proceedings of the Workshop on Food Security and Small tank System in Sri Lanka, 9. Sep.2000. NSF Colombo.

9. Hayley F A, The Laws and Customs of the Sinhalese - Kandyan Law, 1923. Re-printed

Navrang, New Delhi, 1993

10. Geiger, Wilheim. Mahavamsa (Translated from the German). Government press. 1958

11. Gleick Peter H.. Scientific American (Special Report 2005) “Making every drop count”

12. Lansing, Steven. Priests and Programmers – Technologies of Power in the Engineered Landscape of Bali. Princeton. 1991

13. Leach E R, Pul Eliya. Sooriya publication Colombo, 2003.

14. Patrick McCully, Silenced Rivers The Ecology and Politics of Large Dams, Zed books London and New Jersey, 1996.

15. Medduma Bandara. “Small tank cascade systems”

16. Mendis D L O, “Evolution and Development of Irrigation Ecosystems and Social

Formations in Ancient Sri Lanka”. Transactions of the Institution of Engineers, Sri Lanka, 1986

17. Water and Soil Conservation Ecosystems from Ancient Dry Zone Forest Garden to

Modern Jaffna Market Garden. Vishwa Lekha, 2001

18. Mendis D L O, Water Heritage of Sri Lanka, Vishwa Lekha (2002)

19. Panabokke C. R., “The Nature and properties of small tank system of the dry zone and their sustainable production thresholds”, Proceedings of the Workshop on Food security and Small tank System in Sri Lanka, 9. Sep.2000. NSF Colombo

27

20. Parker H. Ancient Ceylon. Lusacs, London, 1908

21. Pfffafenberger B, “The Harsh Facts of Hydraulics: Technology and Society in Sri Lanka’s Traditonal Colonization Schemes”. Technology and Culture, July 1990

22. Weeramantry C G, Environmental Aspects of Sri Lanka’s Ancient Irrigation System.

Separate Opinion, in the Gabcikovo Nagymaros case, International Court of Justice, The Hague. Vishwa Lekha, 2000

23. Weeramantry C G, “The Significance of Sri Lanka’s Ancient Irrigation Technology to

Modern Environmental Law”. Foreword, Arumugam Commemoration volume, 2003

24. Wijewardena, Ray, “Water and Soil Conservation Ecosystems of Sri Lanka”. Preface, Arumugam Commemoration volume, 2003

Resource persons

Mahamankadavala Piyarathana Thera, Eppawala

Dr. James Handawela,

Dr. P. B. Dharmasena, Deputy Director, Field Crops Research Institute, Maha Illukmallama

Dr. Ray Wijewardena, Chancellor University of Moratuwa

Mr. K. M. P. S. Bandara, Department of Irrigation

Mr. Ranjith Rathnayake, Villager at Puleliya

Mr. Prabath Vitharana, Dept. of Agrarian Services

Mr. Punchi Appuhami Village headmen, Lunugamvehera.

28

Appendix I

In ancient systems

1) Local spatial and temporal variation of rainfall and rainfall intensity and natural flows

2) Local spatial ground conditions – matric potential characteristics of soil, infiltration, soil depth

etc. were very much considered

• Water was conserved with highest possible matric potential – when water is stored in soil

its pressure is below the atmospheric pressure. This is due to the attractive forces from

water molicules from the soil matrix.

• Reduce water out flow – this was achieved by considering the topography of the local

bedrock also.

• Water in ecosystem = Blood in body

Unlike a fossil fuel water is in a cycle

• In traditional system, the cyclicity has been improved. This was the main idea behind the

famous statement of the King Parakkrama Bahu the Great: “Let not a drop of water that

falls on this land be allowed to flow into the sea without being made useful to man”.

Rain

sea

Rain

sea

Water

Reuse of water

Pota Vetiya

Kulu vewa

Vewa

29

Appendix II

River Maker at Rajastan India

Rajendra Singh makes rivers flow in the desert as Rajastan using a traditional Indian water

conservation method known as “Johad”. It looks like a semi circular pond, collecting the run off

from tiny streams and rivulets in a much wider area, and allowing it to percolate down and

recharge the ground water below (New Scientist September 2002).

“Traditional knowledge is dismissed

as unscientific. But what’s really

unscientific is not trying to

understand local ecology, climate soil

and culture”