Funday Times

Gaveshaka in his trail along the Anuradhapura gallery

The remarkable irrigation technology
Most of the early settlements of the Sinhalese were in the areas where the rainfall was not very heavy. These areas are the ones referred to as the Dry Zone today. One of the main reasons why these areas were selected for settlements is the fact that the forests in those areas were not so dense and could be cleared without much difficulty, for cultivation. The land was generally flat and more suited for the cultivation of rice, the main food crop, than the valleys in the hilly regions of the Wet Zone.

Rice was cultivated on patches of cleared jungle depending on the seasonal rainfall as well as in fields depending on both rain and irrigation. Reservoirs or tanks were constructed to store water from the heavy rainfall of the monsoons. This water was used to supply the fields when the need arose, in addition to being used as drinking water during the long drought. Naturally the tanks were built near the bigger village settlements. It can be noted that these settlements were closer to rivers where water was readily available.

It is recorded that Prince Vijaya having landed in the soil of Sri Lanka, made his way up a river, the Malwatu Oya and founded the first Aryan settlement. Apart from Anuradhagama on the Malwatu Oya, the next settlement, Upatissagma was on the Kandara Oya, a tributary of the Malwatu Oya. Then there was Uruwela in the deltic area of the Kal Oya, Vijithanagara by the Mahaweli near Polonnaruwa, Digavapi by the Gal Oya in the east coast and Magma by the Kirindi Oya in the deep south.

The Indo-Aryans who came to Sri Lanka and colonized it were knowledgeable about both rice cultivation and irrigation. It was from this basic knowledge that the great engineering skills were developed and exhibited during the times of the ancient Sinhalese kings. Huge reservoirs were constructed and a colossal and complex system of inter-related dams, canals and tanks linked to the waters of rivers flowing in different directions, was put into operation.

Historical records state that irrigation was an area directly under the supervision of the royalty with the 'Yuvaraja' (sub-king) taking charge of the operations. By the first century B.C, the village tank was a well established feature in the dry zone where most of the cultivation took place.

Renowned historian, Professor Senerat Paranavitana mentions that there is reliable historical evidence that at this time two methods of irrigation were practised. One saw small, permanent stone dams across streams as well as temporary dams probably of timber and clay at suitable sites across rivers to divert their water into channels to be conveyed to the irrigable area. The second were the village tanks directly irrigating the fields below their embankments. Nothing more than the village tank had been attempted by the first century B.C. Many of these tanks were privately owned.

King Vasabha (65-109 A.C) was the first of the great tank-building kings. At least 11 tanks were built by him. While they were not huge tanks seen in later times, they were certainly bigger than the village tanks and the largest had perimeters of two or three miles. He also built 12 canals. Elahera Yoda Ela is one of them. Its length was about 30 miles and irrigated a large area. This meant that by the first century B.C. the Sinhalese had developed a high degree of instrumental accuracy in contouring and leveling, and had achieved success in building permanent stone dams across large rivers, Paranavitana says.

While at least 150 tanks and canals are mentioned in numerous inscriptions, in the third century a remarkable advance was made in the science and practice of irrigation engineering. The first colossal tanks came during the reign of king Mahasena (276-303 A.C). He is credited with the construction of 16 tanks and one great canal. The most famous is the Minneriya tank which submerged 4,670 acres and at present irrigates 4,000 acres. The existing Elahera canal was used as the basis of the Minneriya scheme but the dam at the head works and the canal had to be enlarged to divert and carry a much greater volume of water in order to fill the tank.

Nearly as large as the Minneriya tank is the Kavudulu tank, also built by Mahasena. Others included Huruluveva on the Yan Oya, Kanaveva and Kanadiyadora (now known as Mahakandaraveva).

The name of King Dhatusena (459-477 A.C) is associated with the great tank, Kalvapi (Kalaveva) which he built. This huge reservoir submerged an area of ten square miles and the waters were sent to Tisaveva in Anuaradhapura along the Jaya Ganga, an artificial canal 54 miles long. He also built Manamatta tank (identified as the Giant's tank), a reservoir fed by a 17-mile long canal.

Many more kings built canals and tanks and the whole of dry zone both in the north and south was studded with hundreds of large and small reservoirs interconnected by an intricate system of canals providing water to the fields which produced bumper harvests creating a prosperous agricultural economy.

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