Sorabora Wewa and the Unique Natural Stone Sluice (සොරබොර වැව)

The famous Sorabora Wewa, the massive irrigation reservoir of ancient Bintanne lies about 1 km from the current Mahiyangana town and is a must-see destination for visitors of Mahiyangana Rajmaha Viharaya.

Sorabora Wewa which was called the Sea of Binthanne in the ancient past, is unique to all other ancient reservoirs. This is considered the only existing reservoir that does not make use of a Bisokotuwa, the heart of all other large reservoirs of the country. The groundbreaking invention Bosokotuwa, was the single factor that enabled the ancients to build massive reservoirs since the 4th century BCE.

Generally, all the reservoirs have sluice gates that regulate the water flow out of the reservoir on the massive embankments. It was the Bisokotuwa that regulated the water pressure at the sluice gates inside the tank and protected the embankment from erosion.

The builders of the Sorabora Wewa didn’t place the sluice gates at the embankment but used a strategically located natural rock away from the embankment and cut a deep canal which acted as the sluice for the tank. Since the rock was not subject to erosion by the pressure of water, the ancient builders had decided to do away with the tried and tested Bisokotuwa for this creation.

The Sorabora Tank is built by damming the Diyawanna Oya with a 1590-foot (485-meter)  embankment. The tank covers 1100 acres ( 4.5 sq km) and holds 11800 acre feet ( 14.6 Mn sq meters) of water at full capacity. The slice gates are expertly cut into the natural rock and are about 5 feet wide.

The tank is believed to have been built during the 2nd century BCE when the warrior prince Gemunu was warring with the Tamil invader Elara by a relatively unknown general called Bulatha. When army of the Prince Gemunu with his 10 generals (giants) was marching towards Anuradhapura, the army is said to have camped at the village called “Kadali Pathra” (today known as Keselpatha)  near Mahiyangana, It was at this time a strongman called Bulatha (Balathirala) from the village of Kiripattiya in Ududumbara joined the army of the Gemunu.

The task which was assigned to Bulatha was to collect Treacle from Meemure, milk from Kiripattiya, betel leaves from Kevulgama, areca nut from Puwakpitiya ( today known as Popepitiya) daily and deliver these to the king’s castle. With all these villages separated by mountains, his route was treacherous including the Kosgolla mountain pass which which connected the Ududumbara and Minipe areas and was also used by thousands of pilgrims visiting Mahiyangana Rajamaha Viharaya.

While making this daily trip, Bulatha noticed a stream of water passing between two hills and realized that if he could dam this stream, this could be an ideal location for a water reservoir that could provide water for thousands of paddy fields. So every day after his daily trip to the palace with the supplies, he started building the embankment across two hills by himself.

Tradition says that Bulatha was so strong that this mamoty was 10 times bigger than the average mamoty and the basket to remove earth was equally large. His wife living in Kiripattiya too was a woman with a strength of 20 women. She used to travel daily to Mahiyanganaya over the Kosgolla mountain pass bringing Bulatha his meals while he was working on the dam.

Traveling over the treacherous Kosgolla twice a day and seeing thousands of young and old pilgrims traveling the same path, she decided to build a flight of steps over this path to help the pilgrims of Mahiyangana Rajamaha Viharaya. While carrying food to Bulatha, she started adding a few stone steps every day to this path.

When Bulatha completed the reservoir with a 40 feet tall and 11 feet wide embankment that stretched to about 500 meters complete with a unique slice gate away from the embankment cut through a solid natural rock, the wife too had completed her herculean task of adding 2000 stone steps to ease the crossing of Kosgolla pass. Around the same time, King Dutugemunu had completed the renovation of the stupa at the Mahiyanganaya Rajamaha Viharaya after defeating Elara.

On the day King Dutugemunu ceremoniously opened the Mahiyangana Stupa after renovations, Bulatha invited the king to see his secret project which was carried out during his free time. He also showed the herculean task of his wife and Queen Viharamahadevi sent her a special invite to the ceremonial opening of the tank by the king.

After the ceremony, King Dutugemunu is said to have taken off his royal cape and dressed it on Bulatha making him a general in the army and giving him a village called Udathwewa for the contribution he alone has made.

Queen Viharamahadevi too had taken off her necklace and given it to the wife of Bulatha and appointed her the chief of the queen’s security.

The village donated to Bulatha called Udathwewa is today known as Udaththawa and lies about 8 km north of Hasalaka town. There are ruins of a large reservoir at Udaththawa with a sluice gate built similar to Sorabora Wewa and without the use of a Bisokotuwa. Using the natural rock to build the sluice gate seems to be unique to Bulatha and these two tanks are the only 2 known reservoirs in the ancient irrigation history of Sri Lanka to use this technology.

The remains of the stairway over the Kosgolla mountain built by Bulatha’s wife still exist today and this historic route is known as “Galpadipela” today.

Primary Source : Sorabora Wewa Nodutu Ess Motada Pin Kale
by Dharmasena Mahawela

Also See

Map of Sorabora Wewa

Please click on the button below to load the Dynamic Google Map (ගූගල් සිතියම් පහලින්)

The map above also shows other places of interest within a approximately 20 km radius of the current site. Click on any of the markers and the info box to take you to information of these sites

Zoom out the map to see more surrounding locations using the mouse scroll wheel or map controls.

Travel Directions to Sorabora Wewa

Route from Colombo to Sorabora Wewa at Mahiyanganaya
Through : Kelaniya – Ambepussa – Kandy
Distance : 200 km
Travel time : 6-7 hours.
Driving directions: see on Google map


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