Important Days

Harnessing the Mahaweli River - in Ancient Time

The ancients harnessed the resources of the Mahaweli at three points, their most remarkable achievement being at Minipe, then a few miles upstream of Dastota at Kalinga - Nuwara, and at Kandakadu near the deltaic area. They also laid out the intricate Elahera canal system with an anicut across the Amban Ganga, one of the major tributaries of the Mahaweli.

The first attempt at harnessing the Mahaweli could be credited to King Mahasena (AD 275 - 301) who is recorded to have dammed the Mahaweli and built the Pabbatanta canal to irrigate the area around Dimbulagala.

Dhatusena who proclaimed himself king in AD 463 and became famous as the builder of the Kalawewa also constructed a dam across the Mahaweli and " created fields which were permanently watered", according to the ancient chronicle, Culavamsa. This is thought to be a reference to the extension of the Pabbatanta scheme constructed earlier by Mahasena, according to the University History of Ceylon.

Rock inscriptions of the 1st century BC have also revered to a canal, which was taken off the Mahaweli in its broad lower course to irrigate the swampy Minwila. No trace however exists of a stone dam having been built at this point. The method adopt 2,000 years ago to divert the river is therefore a matter for speculation.

A massive attempt to harness the Mahaweli was at Minipe. R. L. Brohier in ANCIENT IRRIGARTION WORKS IN CEYLON states: " It is said that in the reign of King Dasenkeliya (another name of King Dhatusena) there lived on the slopes of the Dumbara mountains a tribe of Veddhas at the time called Yakkos. The king invited them to help in building a large channel and an anicut across the Mahaweli Ganga . . . this giant work which excites the wonder of the modern engineer consists of a scheme which turns the Mahaweli Ganga at a bend in the river where a large body of water enters a narrow channel contiguous to the bank partially closed by two rocks which intercept the water on its return to the main stream. These rocks when united by masonry become a dam raising the waters in the natural channel to a great height."

The Elahera canal on the Amban Ganga was constructed by king Vasabha about 65 A. D. and was later extended by king Mahasena in 475 A. D. to feed Minipe and Kaudulla tanks built by him, and further extended in the seventh Century A. D. to feed Giritale and Kantalai tanks. On the Kalu Ganga a branch of amban Ganga, a diversion dam was built at Hattota and used to irrigate lands immediately under it and to take the excess water to Elahara. Further doun on the Amban Ganga, there was a diversion dam at Angamedilla, built by king Upasena in 368 A.D to feed Topawewa. This same canal was later enlarged by king Parakrama Bahu in 1153 A.D to feed Parakrama Samudra, Topawewa and Nikawewa reservoirs.

On the main Mahawweli River, the Minipe anicut was constructed in about 459 A.D. by King Datusena and irrigated a considerable extent of land on the Left Bank of Minipe on the main Mahaweli Ganga, were also Kalinga Ela and the Gomathi Ela built in the first few centuries A.D to irrigated large extents of land. The Elahera anicut and the channel system up to Kantalai, the Angamedilla anicut and the Left Bank Canal, have been restored and are functioning.

The question of development of the water resources of the Mahaweli to benefit the dry zone, has been raised from time to time in the State council from 1931 and in the house of representative from 1948. The Irrigation Department started the collection of data, and preliminary surveys and investigations in the early 1950,s. the preliminary proposals for the development of he Mahaweli Ganga was published by the irrigation department in 1959. further studies were carried out in the period of 1958 to 1961 by a join United States Operation Mission (as the USAID was then known) the Irrigation Department Team and preliminary proposals for the development of the Development of the Mahaweli Ganga water resources were made in a report published in 1961.
The Mahaweli Ganga, Sri Lanka's main river, rises in the Hatton plateau in the heart of the mountainous center of the island, 1200 m. (4,200 ft) above the sea level. It is joined at Ulapane by the Kotmale Oya, it is most important tributary in the upper reaches, which itself cuts loose from Hortan Plains, a table - top plateau 2134 m. (7000 ft) above sea level. The catchments of both rivers benefit from the NE and SW monsoons and revive an annual rainfall of 4,445 to 5,080 mm. (175 to 200 inches).

Draining more than 16 percent of the island's total land area, the Mahaweli in its 330 km. (206 mls) long, serpentine journey to the sea carries some 7,900 million cu. metres (6,400,000 ac. ft) of water which is more than 20 per cent of the total run of all the island's rivers.

To Sri Lankans who have battled the elemental power of rivers from the 6th century BC, the might of the Mahaweli was always a taunting challenge. Yet the more enterprising Sinhala Kings of ancient Sri Lanka, heirs to a remarkable tradition of irrigation engineering, left behind evidence that they had the measure of the might of the Mahaweli and had indeed come to grips with its main stem, at three separate points.

Indeed, Sri Lanka has a remarkable heritage of ancient irrigation works of truly epic proportions which eloquently testify to the highly sophisticated level of hydraulic engineering practiced by her early craftsmen. Some of these works date back to the 3rd century BC. Most of them are so advanced in design and execution that they have endured to the present day with very little renovation.