Thekkam anicut is believed to have been built during the Anuradhapura Period (Asanga & Nishantha, 2018). The chronicle Mahavamsa states that a channel (present Yoda Ela) was made to bring the water to the Giants tank by King Dhatusena (455-473 A.D.) by damming the river Malwathu Oya. The water was diverted at a location known as Thekkam anicut in Mawathu Oya. The Thekkam Anicut is constructed with giant granite blocks using a rocky foundation at an angle across the river. The Malwathu Oya has been dammed by this anicut about 22 miles from its mouth to divert the river water to Yoda Wewa and to the Akathimurrippu Scheme (Arumugam, 1969). It is a massive structure about 4.3 m high, 200 m long and 4.8 m wide. On the northern side of the anicut, there are three large openings to release excess water. This ancient dam was renovated during the Polonnaruwa Period and finally during the British Period (1815- 1948 A.D.). A canal has been cut to carry the diverted waters just before the anicut. The canal snakes through the natural counters of the terrain parallel to the Malwathu Oya for over 10 km before turning north and finding its own route to the final destination. The total length of this marvel is about 25 km.

The structure represents a milestone / turning points in development of irrigated agriculture and bears an exceptional testimony to development of agriculture and increase in food production along with the improvement of economic condition of farmers;

Malwathu Oya basin was among the regions that supported the original civilization in Sri Lanka at the time. Prince Vijaya landed near the river estuary. The landing was not by chance; the location was part of the ancient trade route, with pearls being found in the nearby sea. Giants tank in Mannar is the lifeline for hundreds of paddy cultivators in the area known as the Paddy Bowl of Sri Lanka; this is the second largest reservoir made in ancient Sri Lanka, with a 7.4 km long curving dam attributed to King Dhatusena (459-477) who diverted water from Malwathu Oya and a built a 25 km long canal along the flat land to build Yoda Wewa. This reservoir was an experiment of a gigantic scale since the conventional reservoirs were built across a river or stream encompassing a valley for several miles over a large area of a river basin, creating a reservoir. The land in the Mannar district was so flat that a new way to irrigate the land was required. The engineers under king Dhatusena then decided to build a 25 km long canal from Malwathu Oya to a natural depression in the area where the Giants tank stands today. Although the reservoir lies just over 5 km from Malwathu Oya as the crow flies, the engineers selected a location almost 20 km upstream to divert the water considering the level of the river and the reservoir to build the Thekkam anicut. An analysis done by British scholars of a concrete sample dating back six centuries (at that time) in 1889 obtained from an anicut associated with Giants Tank in Mannar (Thekkam Anicut) is described below. This article explains to us that usage of the best quality raw materials for the construction of irrigation systems was one of the main reasons for the success of our ancient irrigation heritage.

The structure made outstanding contribution to enhancing food production, livelihood opportunities, rural prosperity, and poverty alleviation in a region;

Malwathu Oya basin was among the regions that supported the original civilization in Sri Lanka at the time. Prince Vijaya landed near the river estuary. The landing was not by chance; the location was part of the ancient trade route, with pearls being found in the nearby sea. Giants tank in Mannar is the lifeline for hundreds of paddy cultivators in the area known as the Paddy Bowl of Sri Lanka; this is the second largest reservoir made in ancient Sri Lanka, with a 7.4 km long curving dam attributed to King Dhatusena (459-477) who diverted water from Malwathu Oya and a built a 25 km long canal along the flat land to build Yoda Wewa. This reservoir was an experiment of a gigantic scale since the conventional reservoirs were built across a river or stream encompassing a valley for several miles over a large area of a river basin, creating a reservoir. The land in the Mannar district was so flat that a new way to irrigate the land was required. The engineers under king Dhatusena then decided to build a 25 km long canal from Malwathu Oya to a natural depression in the area where the Giants tank stands today. Although the reservoir lies just over 5 km from Malwathu Oya as the crow flies, the engineers selected a location almost 20 km upstream to divert the water considering the level of the river and the reservoir to build the Thekkam anicut. An analysis done by British scholars of a concrete sample dating back six centuries (at that time) in 1889 obtained from an anicut associated with Giants Tank in Mannar (Thekkam Anicut) is described below. This article explains to us that usage of the best quality raw materials for the construction of irrigation systems was one of the main reasons for the success of our ancient irrigation heritage.

The structure contributed to the evolution of efficient and contemporary engineering theories and practices;

Malwathu Oya basin was among the regions that supported the original civilization in Sri Lanka at the time. Prince Vijaya landed near the river estuary. The landing was not by chance; the location was part of the ancient trade route, with pearls being found in the nearby sea. Giants tank in Mannar is the lifeline for hundreds of paddy cultivators in the area known as the Paddy Bowl of Sri Lanka; this is the second largest reservoir made in ancient Sri Lanka, with a 7.4 km long curving dam attributed to King Dhatusena (459-477) who diverted water from Malwathu Oya and a built a 25 km long canal along the flat land to build Yoda Wewa. This reservoir was an experiment of a gigantic scale since the conventional reservoirs were built across a river or stream encompassing a valley for several miles over a large area of a river basin, creating a reservoir. The land in the Mannar district was so flat that a new way to irrigate the land was required. The engineers under king Dhatusena then decided to build a 25 km long canal from Malwathu Oya to a natural depression in the area where the Giants tank stands today. Although the reservoir lies just over 5 km from Malwathu Oya as the crow flies, the engineers selected a location almost 20 km upstream to divert the water considering the level of the river and the reservoir to build the Thekkam anicut. An analysis done by British scholars of a concrete sample dating back six centuries (at that time) in 1889 obtained from an anicut associated with Giants Tank in Mannar (Thekkam Anicut) is described below. This article explains to us that usage of the best quality raw materials for the construction of irrigation systems was one of the main reasons for the success of our ancient irrigation heritage.

The structure was unique in some positive and constructive way;

Malwathu Oya basin was among the regions that supported the original civilization in Sri Lanka at the time. Prince Vijaya landed near the river estuary. The landing was not by chance; the location was part of the ancient trade route, with pearls being found in the nearby sea. Giants tank in Mannar is the lifeline for hundreds of paddy cultivators in the area known as the Paddy Bowl of Sri Lanka; this is the second largest reservoir made in ancient Sri Lanka, with a 7.4 km long curving dam attributed to King Dhatusena (459-477) who diverted water from Malwathu Oya and a built a 25 km long canal along the flat land to build Yoda Wewa. This reservoir was an experiment of a gigantic scale since the conventional reservoirs were built across a river or stream encompassing a valley for several miles over a large area of a river basin, creating a reservoir. The land in the Mannar district was so flat that a new way to irrigate the land was required. The engineers under king Dhatusena then decided to build a 25 km long canal from Malwathu Oya to a natural depression in the area where the Giants tank stands today. Although the reservoir lies just over 5 km from Malwathu Oya as the crow flies, the engineers selected a location almost 20 km upstream to divert the water considering the level of the river and the reservoir to build the Thekkam anicut. An analysis done by British scholars of a concrete sample dating back six centuries (at that time) in 1889 obtained from an anicut associated with Giants Tank in Mannar (Thekkam Anicut) is described below. This article explains to us that usage of the best quality raw materials for the construction of irrigation systems was one of the main reasons for the success of our ancient irrigation heritage.

The structure bears the stamp of a cultural tradition or a civilization of past;

Malwathu Oya basin was among the regions that supported the original civilization in Sri Lanka at the time. Prince Vijaya landed near the river estuary. The landing was not by chance; the location was part of the ancient trade route, with pearls being found in the nearby sea. Giants tank in Mannar is the lifeline for hundreds of paddy cultivators in the area known as the Paddy Bowl of Sri Lanka; this is the second largest reservoir made in ancient Sri Lanka, with a 7.4 km long curving dam attributed to King Dhatusena (459-477) who diverted water from Malwathu Oya and a built a 25 km long canal along the flat land to build Yoda Wewa. This reservoir was an experiment of a gigantic scale since the conventional reservoirs were built across a river or stream encompassing a valley for several miles over a large area of a river basin, creating a reservoir. The land in the Mannar district was so flat that a new way to irrigate the land was required. The engineers under king Dhatusena then decided to build a 25 km long canal from Malwathu Oya to a natural depression in the area where the Giants tank stands today. Although the reservoir lies just over 5 km from Malwathu Oya as the crow flies, the engineers selected a location almost 20 km upstream to divert the water considering the level of the river and the reservoir to build the Thekkam anicut. An analysis done by British scholars of a concrete sample dating back six centuries (at that time) in 1889 obtained from an anicut associated with Giants Tank in Mannar (Thekkam Anicut) is described below. This article explains to us that usage of the best quality raw materials for the construction of irrigation systems was one of the main reasons for the success of our ancient irrigation heritage.