Ancient irrigation systems in Sri Lanka

Irrigation systems in Sri Lanka

Water is one of the basic needs of Human. Therefore utilization of water has a history of thousands of years. From that, Sri Lanka has a great history towards irrigation. Irrigation is known as the arrangement for transporting water from areas of abundance to an area of shortage. This includes works for the collection, transmission, treatment, storage, and distribution of water.

In the early era, people became colonized & after the ‘hunting & gathering’ era, people moved to a settlement & started their own plant cultivation & animal husbandry. As they settle down to one place, their main concern was water. They made their colonies on the river banks where they will access unlimited water. At this stage, they thought water resource cannot be changed to their wish. In Sri Lanka, along the river banks of Malwathu Oya, archeological evidence can be found for such civilization.

But, these river banks were not sufficient with the incensement of the population. People needed vast area of land for their cultivation. Land areas on river banks were insufficient. Therefore, people needed far more advance system of water supply. This was the starting of the advance irrigation systems. These irrigation systems were first started with the canals made for water transportation to the cultivated lands from the rivers. By this time, wet Rice cultivation has become one of the main food resource along with Thala, Meneri,Mun & Kurakkan which didn’t needed water as for Rice.   Around 4th century B.C. after creating the first capital of Sri Lanka; Anuradhapra, after that Polonnaruwa, people had to face a lot of difficulties. The Anuradhapura & Polonnaruwa areas lack water in some periods of the year. This was a major problem as people had to stay a long time after one harvest. Some years, only one harvesting was possible. Therefore, cultivation during the raining seasons was not enough. Till this time, people thought that rivers are flowing on their own; which human can’t change. They thought that human should adapt to the situation. They didn’t try to change the rivers or store water.

Ancient Kings tried to find a solution for the water problem & ended up with a network of irrigation based on the Wewa. The first recorded wewa is the Abaya wewa built by King Pandukabhaya. After that, thousands of wewa was created all over the country with the concept of ‘Gamai Pansalai, Wewai Daagabai’, especially in the dry zone, where water was vital. So, one reservoir was created for one village. These reservoirs created included small scale to massive reservoirs seems to be like the sea.

These water reservoirs created by man, was able to collect & store the rain water as well as water flown in rivers, so that water will be available in the dry seasons as well. Then, networks of canals were needed to distribute the collected water. For the places where this water supply was unavailable, people used the Wells as water resource.

Technology behind the Ancient irrigation systems in Sri Lanka.

Technology, the people in Sri Lanka used in the irrigation is still unbelievable. With using small techniques people have created unbelievable. One of the main features is that people have created these irrigation networks with the minimum effect to the environment & in an environmental friendly way. In the Jayaganga, the depth per one mile increased by 6 inches along its first 24 miles of 54 miles. This shows the talent of taking smooth measurements & creating things with maximum accuracy.

In creating Wewa, people have thought of the best place for the dam to be made. That place had include,

1. A rocky basement 2. Closest place, joining two high places 3. The maximum depth that can be taken for the reservoir.

Therefore, this indicates that early people knew of the basement & it’s use with how to utilize the resources effectively.

The pressure controlling techniques used in Wewa is remarkable. In the Dam & Water outlet, ancients have used highly advanced techniques. Bisokotuwa is one of the structures used in controlling the pressure. Still some of the Bisokotu are in working condition.(Sora bora Wewa)

In seegiriya, we can observe the irrigation systems & networks used. Especially the water ways for the ponds, which are working even today. Another main feature is that these people had a talent of doing everything symmetrically. Even the laid pipe lines are laid in symmetrically. Ancients have used the Bernoulli principle effectively long before the principle is found.

Documented by Bhanu Watawana(Uva Wellassa University)