The Yodha Wewa in Mannar is one of the largest tanks in the island and was It was built by King Dhatusena (459-477) by damming and diverting water from the Malwatu-oya. Known as Manawatu Wewa in the ancient times, the tank is fed by a 25 km ancient canal, recently restored, which carries water from the Malwatu Oya river.
British irrigation engineers who discovered Yoda Weva ( Giant’s Tank) in the 19th century failed to comprehend the design of this tank which was in ruins and considered a great failure. Sir James Emerson Tennent in 1860 wrote in his publication ” Ceylon – an account of the island physical, historical, and topographical with notices or its natural history. antiquities and productions” :
“From Anarajapoora, I returned to the west coast, following the line of the Malwatte-oya, the ancient Kadamba, which flows into the Gulf of Manaar, north of Aripo. Within a few miles of the coast our party passed, at Taikum, the immense causeway of cut granite, two hundred and fifty yards in length, and upwards of fifteen feet high, by which it was attempted to divert the waters of the river into the canal, that was designed to supply the Giants’ Tank. None of the great reservoirs of Ceylon have attracted so much attention as this stupendous work. The retaining bund of the reservoir, which is three hundred feet broad at the base, can be traced for more than fifteen miles, and, From Anarajapoora, I returned to the west coast, following the line of the Malwatte-oya, the ancient Kadamba, which flows into the Gulf of Manaar, north of Aripo.
Within a few miles of the coast our party passed, at Taikum, the immense causeway of cut granite, two hundred and fifty yards in length, and upwards of fifteen feet high, by which it was attempted to divert the waters of the river into the canal, that was designed to supply the Giants’ Tank. None of the great reservoirs of Ceylon have attracted so much attention as this stupendous work.
The retaining bund of the reservoir, which is three hundred feet broad at the base, can be traced for more than fifteen miles, and,as the country is level, the area· which its waters were intended to cover would have been nearly equal to that of the lake of Geneva. At the present day the bed of the tank is the site of ten Populous villages, and of eight which are now deserted. Its restoration was successively an object of solicitude to the Dutch and British Governments, and surveys were ordered at various times to determine the expediency of reconstructing it. Its history has always been a subject of unsatisfied inquiry, as the national chronicles contain no record of its founder. A recent discovery has, however, served to damp alike historical and utilitarian speculations; for it has been ascertained that, owing to an error in the original levels, the canal from the river, instead of feeding the tank, returned its unavailing waters to the channel of the Malwatte river. Hence the costly embankment was an utter waste of labour, and the Singhalese historians, disheartened by the failure of the attempt, appeared to have made no record of the persons or the period at which the abortive enterprise was undertaken.”
Dr. Ananda W.P. Guruge in The waterlords of ancient Sri Lanka ( UNESCO Courier , Jan, 1985 ) describes this failure of modern european engineers to comprehend the ancient wisdom in Sri Lanka,
“Many a modern engineer has been baffled by the sophisticated designs on which these reservoirs and channel systems were constructed. It is known that the Dutch engineers of the eighteenth century and their British counterparts in the nineteenth failed to understand the design of the giant tank near Mannar on the northwestern coast. Only in recent years, when the tank was restored in conformity with the original design, was it found that leveling by the unknown engineer of the past was vastly superior to that attempted by modern engineers.”
There were two parallel line of embankment towards the sea which were then joined by a flat curved bund, the bund thus enclosed the tank on three sides, making it possible to irrigate the land on both flanks as well as the land in front. Though British condemned this as unsuccessful engineering, Brohier saw the thinking behind it. Work on the Giants tank appears to have been done in sections. The earthworks at the two ends of the embankment and the feeder channels were constructed simultaneously. Usually, the transbasin canals were built first and the tank was built thereafter.
Yoda Wewa is situated about 25km southeast of Mannar in the Mannar District in a semi-arid zone. A part of the tank bund is located along the Madawachchiya – Mannar Road. The water from this tank is fed to 162 smaller tanks downstream and irrigates about 11,000 hectares of paddy land.
The embankment of Yodha Wewa is over 7 km in length with a height of 14 feet. This is comparitively a low height considering other reservoirs of same size. But it is clear that ancient irrigation engineers has considered the flat land in the area and increased the volume of the tank by increasing the area of water spread rather than increasing the depth of the tank. The tank now covers over 4550 hectares ( 45.5 sq. km) and capable of carrying 31,500 acre feet ( 39 Mn cubic meters) of water.
For almost 3 decades parts of this tank was under Tamil Tiger terrorists and the maintenance was neglected due to security reasons. The area which was farmed with the waters were engulfed by the jungle. But in 2008 this area was totally liberated by the Sri Lankan Armed forces and restoration of the tank has already begun. Once the tank is fully restored to carry the full volume of water, this area known as the rice bowl of the country will once again live up to its name.
- Hydro Heritage of Sri Lanka
- Ancient Heritage Sites of Sri Lanka
- Other Places of Interest Within Close Proximity
Map of the Yoda Wewa at Mannar
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Traveling to Directions to Yoda Wewa at Mannar
|Route from Anuradhapura to Yoda Wewa in Mannar|
|Through : Medawachchiya|
Distance : 95 km
Travel time :1.30 hours
Driving directions : see on google map