Sunday Observer Online


Sunday, 5 June 2011





Marriage Proposals
Government Gazette

Great engineering feats III

Ancient and modern tanks

The hydraulic civilisation of our country is a great pride to us. We have to be grateful to the kings who ruled the country and also our highly skilled ancestors for leaving behind such a remarkable heritage. Many of you may have seen the mighty tanks and reservoirs that dot the country and been fascinated by the expertise displayed by our ancient tank builders. Apart from the numerous massive tanks built by our ancient kings many new reservoirs have also been built during modern times and these are as impressive as the ones constructed in the past.In the last two weeks we featured some of these tanks and today too we continue the series featuring a few ancient and modern tanks that have become the lifeline of farmers.

Some of these massive tanks also supplement the hydro power capacity in the country. These engineering marvels are important places that you must learn about and if possible visit as they play a key role in the agriculture and economic development of the country.


Maduru Oya Reservoir

It is the first major project (1978) taken up for construction under the Acceleratedf Mahaweli Development Programme straddling the Maduru Oya .

This reservoir is of great significance because a masterpiece of irrigation construction,an ancient sluice on the old ruptured earthen bund of the Maduru Oya, was discovered at the very location surveyed and calculated by the local and foreign irrigation engineering experts to build this new dam in 1981.

The ancient earthen dam and sluice built during the reign of King Mahasena (275-301 B.C.) made up of stone slabs and bricks, is about 30 feet (9.1 m) high, 30 feet (9.1 m) wide and 219 feet (67 m) long.

The upper sluice was built in two phases, the first of which dates to before the 6th century BC.

The lower sluice is believed to be older than that.Many marvelled at this discovery as it proved that the ancient engineers of our land were very knowledgeable and highly skilled.Modern western engineering had just managed to match the ancient hydraulic engineering of Sri Lanka.This made many realise that our ancient Sinhalese irrigation engineering and the hydraulic civilisation of Sri Lanka,has been second to none.

The Maduru Oya has its source to the North-east of Central Highlands of Sri Lanka at Uva hills east of Bibile at an elevation of 274 m. (900 ft.) above sea level.

It flows north-eastwards covering a distance of about 136 km. and disgorges into the Vandaloos bay near lovely beaches of Kalkudah and Passikudha on the east coast.


Catchment area :453

Length and height:1090 m and 43 m

Capacity:597 million cu.m


Tissa Wewa

This massive tank which was built by King Devanampiya Tissa ( 250-210 BC) is located in north central Sri Lanka, near the city of Anuradhapura, in the dry zone.

The terrain is very flat.It has an area of approximately 550 acres and the width of the top of the reservoir was found to be 12 feet to 18 feet. Only Panda Wewa and Abhaya Wewa are considered to be older than Tissa Wewa.

Parker in 1909 reports that the embankment appears to be in original state ( that of 1100 years ago) and its so solidly built, with little maintenance this bund will last forever.

Just as he commented, the Tissa Wewa continues to provide water to the Anuradhapura even today.In 1887 the Tissa Wewa too had been rehabilitated by the British .

The water in the tank is used for irrigation, drinking water, washing,and daily and recreational bathing.It is said that in the time of the kings,Tissa Wewa fed two rock cut stone bathing pools in Ranmasu Uyana. Brick-topped granite channels direct water along the base of the bund, divert it through silt traps, and pour it into the embedded tiers of the pools.


Catchment area: 6.5

Length and height: 3480 m and 11m

Capacity: 4.3 million cu.m


Chandrika Wewa

Chandrika Wewa which holds a unique position among the major irrigation constructions in the Walawe Basin is entirely a contempory irrigation construction. Due to the Chandrika Wewa Agricultural Colony Project it was possible to settle a large number of people in the Walawe basin which recorded very few people in the 1960s. Pulanda Oya, a tributary to the Walawe River was blocked with a 2500m long bund to build this reservoir.Currently there is a water management system which links Thunkama, Angunukolapalassa,Binkama, Muraweduihena and Basawakkaulama to Chandrika Wewa.

In addition to that it provides potable water for the people of the area.


Catchment area : 203

Length and height: 2500 m and 19 m

Capacity: 27 million cu.m


Kaudulla Wewa

King Mahasena is credited with the constuction of this great wewa which is also identified as the 'Thissawaddamana Vapi' or'Ranthisa Wewa'.

Acccording to the chronicles, both King Vijayabahu (1055-1110) and King Parakramabahu the Great, (1153-1186) respectively had carried out rehabilitation work on the tank which was formed by building a bund across Kaudulu Oya.

It receives water along the Elahera-Kantale Giant Canal which begins at Elahera Anicut on Amban Ganga, built by King Vasabha.Gal Oya and Aluth Oya are two natural water reservoirs located in Kaudulla Wewa.


Catchment area :348

Length and height:9234 m and 15 m

Capacity:64 million cu.m


Nuwara Wewa

The largest of the three man-made reservoirs in Anuradhapura it is believed to have been built by King Vattagamini Abaya popularly known as King Valagamba in the first century BC.

A massive dam had been built across the Malwathu Oya to divert water to this tank which covers an area of 3180 hectares.

From the dam a 40 feet wide channel has been cut to bring the water to the Nuwara Wewa.

The canal has a depth of about four feet. At about 150 feet from the dam, a flood escape had been built to divert the excess water back to the river.

The bricks used to construct the wewa are believed to be similar to those used in the famous Abayagiriya Stupa and going by this H.Parker claims in his book Ancient Ceylon that the tank may have been constructed in the first 20 years of the 1st century BC.

In 1873 nearly all these rocks had been removed to be used to erect a road bridge across the river.Restoration work on the wewa had been carried out in 1890 by the British.


Catchment area: 51

Length and height: 6500m and 11m

Capacity: 44 million cu.m


Usagala-Siyambalagamuwa Wewa

This ancient irrigation scheme which is located in the Kala Oya basin is said to be yet another remarkable construction by King Mahasena (276-303).

According to historians, King Mahinda II (777-797) had built a 16 miles long feeder canal from Kala Wewa to supply water to Usagala-Siyambalagamuwa. The ancient chronicle the Mahawamsa says King Buwanekabahu (1534-1542) also rehabilitated it and cultivated 500 amunu (750 acres) of paddy.

The first colonial report of this site was published in 1877. The rehabilitation work carried out by Irrigation Department saw its completion when it was filled in 1955.


Catchment area :184

Length and height:1433 m and 4 m

Capacity: 27 million cu.m


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