The 3,000 year-old system that still serves its people. Sri Lanka’s hydraulic heritage must be understood in order to be protected; the ancient Philosophy of Water and Soil Conservation in an Island-Civilization that was the amongst the greatest in the world.
This essay will introduce you to the very basic principals upon which our Hydraulic Civilization was built upon.
And hopefully, it will inspire you to do your own research, and discovery our amazing heritage.
A quote attributed to the great Sri Lankan King, Parakramabahu (1153–1186) and cited in Sri Lanka’s historic chronical, the Mahawamsa, has been misquoted and as a result, misunderstood for decades. In it, the King decrees that
‘…not even a little drop of water that comes from the rain must flow into the ocean without being made useful to man”.
In fact, the Great King never used the word ‘man’. The Mahavamsa quotes him to have challenged his Kingdom to not allow a single drop of rainwater from being released into the Ocean without it being used and reused for the
‘…benefit of all the earth’.
The Sinhala translation of the Pali word used is, ‘Lokopakarayen’.
This one, powerful word captures the essence of Sri Lanka’s ancient hydraulic heritage philosophy- one that was designed to protect the environment with man being part of that environment and not solely for the benefit of man alone.
While the West has woken up to the importance of sustainability of late, the Sri Lankan civilization was built on a culture of sustainability that lasted for thousands of years.
A key misconception that must be righted is the fact that we often think our water heritage is limited to our irrigation systems.
An irrigation system is a function of hydraulic engineers who will see water as ‘inanimate and active’ but rather the conservationist and farmer will see water from the perspective of it being animate and passive.
The consequences of this difference in understanding our water resources has been disastrous especially in modern times.
Irrigation planners and engineers essentially look at ways of moving water from A to B in the most efficient and effective manner.
Whereas the meandering process of our ancient conservationists took into consideration soil nourishment, filtration, sustaining wildlife and forests, and most importantly replenishing and recycling water.
It was this holistic approach to water management that led to the creation of some of the most stupendous water works the world has ever seen.
Sri Lanka’s ancient water systems include large and small-tanks, river diversions, storage systems and interconnected canals. Of this, perhaps only the largest ‘storage reservoirs’ have become part of popular history and touted as showpieces of our historic prowess as a hydraulic civilization.
One would be hard-pressed to find a political speech or a patriotic song that does not refer to our ‘wewa’s and the Kings who led their construction.
But to understand the extent of this hydraulic heritage is an entirely separate exercise that demands an understanding not only of Sri Lanka’s murky history in the context of parallel world civilizations but also of our geology and weather patterns etc.
As they say, the truth is stranger than fiction. While irrigation and storage are a main function of water management, flood control, drainage and conservation of water, soil and biomass are equally important.
And to achieve this our ancients devised ingenious innovations that stood the test of time.
For instance, when the British colonialists discovered the Minneriya ‘tank’ built by King Mahasen in the 4th Century, the earthen dam had not been breached and was in perfect working condition. A system that had lasted over 15 Centuries and remained operational.
I cannot think of anything else, anywhere in the world, that can bare testament to such sustainable effectiveness.
Strength as defined in the Sri Lankan hydraulic heritage context then is less about solidity and rigidity and more about a seamless integration into a larger philosophy that works in harmony with nature and therefore, lasts longer. This is the major impasse between modern irrigation thinking and the sustainable structures of our ancients.
‘Cascade Systems’- small tank clusters, a wonder of the world
Very early in Sri Lankan history, our people acquired the art of conserving rain water to tide over the long annual drought that afflicts three fourths of the country, and the bunding-up of rivers and streams, according to our historical records has been an established science even before the arrival of Vijaya in 543 BC.
Increasing sophistication led to the evolution of multi-purpose projects, with conveyance structures linking many a river-basin spread over wide tracts of territory, and the utilization of her waterways for storage, regulation, irrigation, flood-protection, trans-basin diversion, water transport and fisheries, practiced with exceptional skill by our ancients until around the 5th Century AD.
It can be said that Sri Lanka had attained the zenith of her ‘tank’ or ‘wew’ civilization and well over twelve thousand man-made reservoirs adorned her landscape; that’s approximately one for every two square miles of territory.
An intensity of irrigation effort that perhaps no other civilization can claim to equal. Our ancient Kings in their wisdom and foresight, pushed to the very limits, the resources and technology available to them at the time, and to which the ruined remains of their mighty handiwork bear testimony for present-day leaders to ponder over with admiration and, shame, no doubt.
For what might our ancestors have achieved had they but a fraction of the technology and know-how at our command today?
So, what is a ‘Cascade System’, exactly?
There’s no way to simplify these systems but I will try. Think of the undulating geography of Sri Lanka’s dry zone. The rise and fall of the topography of the land meant that, naturally, rainwater would flow and then collect in certain areas.
Our ancients observed these natural occurrences over time and began to think of ways to harness this natural behavior to structure their farming around the ready supply of water.
And so, what they did, was construct barriers at certain locations that would in effect, create storage areas. The storage ‘tanks’ were then connected via canals and sometimes, ducts, to each other creating a link of anywhere between 3 to sometimes 30 small tanks that acted in unison to irrigate and nourish a definable area.
It was around this ‘system’ that our villages were formed, and thereby, our culture.
Unfortunately, today, the ‘Wewa’, is inappropriately referred to as a ‘tank’. Writing on Lessons from Civilization Principle of Wewa for World Peace Policy, Engineer SK Sooriyarachchi, perhaps put it best when he defined the system, by virtue of its concept, as-
“an ‘ecosystem’ itself, neither an isolated reservoir nor a number of reservoirs linked together in a cascade but rather a composite ecosystem comprising of a cascade of reservoirs associated with its own catchment, supporting human life and livelihoods such as paddy cultivation, people and animals associated with it, the soil and ground water table and al altogether pleasant environment around it”.
The Sri Lankan ‘wewa’ and ‘canal’ systems- a technological marvel
The first question our ancients had to answer when thinking about building a ‘wewa’, was the geography of the area. Selecting the location and then ‘bunding’ the appropriate gaps was done using earthen material.
What is important to note here is that our ancient engineers never really ‘built’ entire reservoirs as we might sometimes imagine they did. What they did was, instead, ingeniously, ‘bund’, the right areas. This is why the Rajarata region in Sri Lanka is called the ‘wew bandi raajya’, and not the ‘wew hedu raajya’. Perhas a negligible difference to some, but significant in the philosophy and approach to Water Management.
Everything was about sustainability and conservation. Not all ‘wew’ were the same. There were different wew for different purposes.
There were ‘Kotu Wew’, which were the smallest and oldest, at most 2–3 acres. The ‘Kulu Wew’ served the very specific function of storing excess water required for larger storage tanks.
What made these wewas special, was a lack of Sluice Gates, as they were not used for…