The wonders of village wewa (tank) and how we treat them!
The small tank (wewa) based villages are a unique feature in the landscape of Sri Lanka Dry Zone in particular. The tanks occur in clusters called cascades within which are many different types of tanks with some of them are mere water holes yet performing a significant role. In no other place human were living in full harmony with the environment than in the small tank based villages in Sri Lanka. The tanks in fact are people-centered eco-systems. The eco-system itself consists of tree clad forest catchments, submerged areas with other types of plants, water body protected by water plants, the earthen and other structures well protected by plant species, drain water area, unknown plant and wildlife relationships supporting the equilibrium of the eco-system, highland areas, and domesticated animals.
The history of tank-based civilization goes back to the year 450 B.C. when the first tank reported to have been built. This particular tank is still in operation.
The village tank based eco-systems have undergone so many changes during the last 2500 years or so with the changes after the 18th century being so acute. The latter changes have virtually killed these eco-systems which were in equilibrium with nature. Although the association between the tank eco-system and people is very long, we have still failed to understand their functioning in full. In the first instance, there is no accurate data of the total number of tanks and their associated structures in existence. Of them, different statistics occur in terms of the number functioning with no reference to the smallest structures within the cascades called wala and wetiya. Over the years, some research mainly in fragmented nature have been conducted to understand the functioning of these small tanks as well as to quantify human benefits. However, a huge wealth of information on these indigenous systems are yet to be uncovered. The steady decline of old people who have a wealth of information on the functioning of these tank based villages is a main problem in tapping this knowledge.
From time to time, there have been several efforts including large scale and funded projects to “improve” functioning of these irrigation systems. The approach of subsequent colonial governments has been to “formalize” the tank based systems. The largest mistake of all their efforts has been to “acquire” tank-based irrigation systems, a de facto practice continued even today. Beginning in the 1970s, several large scale and funded projects have been implemented to “rehabilitate” small tanks with dismal failures. Regrettably, the rehabilitation had been based on the calculation of the magic figure of IRR considering rice and other crops produced from the water stored in a given tank. These calculations have not included the many and varied other benefits resulting from small tanks.
The small tank wonders!
The small tank eco-systems are wonders where the nature and human beings are in co-existence with mutual support and dependencies to each other.
Through literature and field observations, it is learnt that these tank eco-systems appear as centers of fourfold wonders as outlined below:
An unknown number of trees, shrubs, lianas and plants are involved to collect, store, conserve, reduce waste and purify water as well as to encourage recharge of underground aquifers. Several of flora have unique adaptations to the system which remain a mystery.
A large number of plants support animal life and several ecological processes on which our current understanding is minimal.
An array of physical structures both man-made and natural are engaged to maximise run off collection and storage, to conserve water and to provide benefits both to people and animals living within. All structures are made by human and animal power using indigenous technology
Institutional mechanisms and social processes:
• To support and facilitate protection, proper functioning and sustainability of physical structures and biological parts of the eco-system
• To facilitate the co-existence of human beings and eco-systems in harmony ensuring the needs of people are met with equity
• To reduce conflicts, provide entertainments and to support livelihoods on a sustained basis
Physical, biological and human resources focused to provide a multiplicity of benefits from the entire system as a whole rather than benefits derived from any specific component such as crop production based on irrigation (see Table below).
A list of common and known benefits from small tank systems is summarized in the table below.
Tank and canal water
Benefits: Water for domestic purposes; irrigation; livestock and wildlife use; buffalo wallowing; recharge drinking wells; sustenance of fish and fish production; tank water is source of entertainment; seepage water support tree growth; cools down dryness
Benefits: Edible lotus seeds; rice from Oolu seeds; handicrafts; food such as lotus yams; vegetables; medicines
Plants from tank bund and other parts
Benefits: Vegetables; medicine; beverage; food; fiber; fodder
In addition, all tank components and the cascade as a whole support unidentified ecological processes and benefits as well. Such benefits remain unknown to us even today.
Considering these benefits, it is clear that a conventional costs and benefits analysis will certainly not help. An extended costs and benefits analysis should be the answer. To dismay of us all, none of the large scale projects to “rehabilitate” these tanks had ever been supported by an extended costs and benefits analysis. In other words, all past “rehabilitation” efforts have been guided by conventional costs and benefits analyses where the centre of focus has been on the value of irrigated crops produced. Mainly as a result of this poor analysis and the weaknesses of the “experts” utilized, it has not been able to understand this wonderful tank culture and its benefits leading to insufficient improvement options.
Our heritage and world wonder !
A comprehensive program of research (on structures, methods and practices, role of plants and other biological components, institutional mechanisms and processes, etc.) to understand the functioning of the small tank system though late is still possible. The outcome of the analysis, no doubt, will unfold a wealth of information which is likely to emerge small tank based eco-systems as an important part of our heritage. The results may also lead to recognize small tank eco-systems as a world wonder too.