Though not the largest ancient reservoir in Sri Lanka, the tank known as Kalawewa is considered to be a major achievement of the ancient Sinhalese hydraulic civilization and of utmost historical importance. There are several reasons for the extraordinary significance of the Kalawewa. Firstly, it was a masterpiece of exact engineering calculation. Secondly, it was the first time that another river system, that of the Kala Oya, was utilized for irrigation of Anuradhapura, which is located at the Malwattu Oya. Thirdly, the history of the construction of Kalawewa is intimately connected with the most famous case of patricide in Sri Lankan history.
Kalawewa & Ancient Irrigation System of Sri Lanka
The historic Kalwewa reservoir, called Kalavapi in the chronicles, is famous because its builder, King Dhatusena (460-78), considered it his major achievement, for which he then paid with his life. At least that's what the national chronicle Mahavamsa (or more precisely, its sequel often called Chulavansa) reports, in a story that serves is a prelude to the narative of the founding of the world-famous rock fortress Sigiriya.
The circumference of the ancient reservoir Kalawewa, which is functional again, is now over 60 km. Depending on the water levels, it usually covers an area of 18 square kilometers (7 square miles). The Kalawewa is still not the largest of the reservoirs of the Anuradhapura period. But it was in a sense the heart of the ancient irrigation network, one of the most astonishing achievements of the hydraulic civilizations of Asia. The Kalawewa was the most important water distributor for many other reservoirs and is again today. Before the construction of the Kalawewa, only the water from the Malwattu Oya river system, which runs through the central former royal land "Rajarata", which is today's cultural triangle, was used for irrigation of the cultivated area around Anuradhapura. However, the southern Kala Oya river, which rises on the northern edge of the mountains, is richer in water than the said Malwattu Oya. Damming the Kala Oya potentially led to more than doubling the amount of water available, at least if its water could be diverted to the Anuradhapura area. And that's exactly what the Jayaganga Canal was used for, an artificial drainage of the Kala Oya waters from the Kalawewa towards the north to the tanks at Anuradhapura. The Jayaganga Canal was therefore an integral part of Dhatusena's Kalawewa project. Another drainage canal drained water westwards to the Siyambalagamuwa Reservoir, which fed 30 other tanks of smaller size.
There are ancient reports that even another mountain river beyond the main watershed, the Amban Ganga, was tapped for the Kalawewa by digging a tunnel to the Minisgoni Oya, which is a second river feeding the Kalawewa. However, such a tunnel has not yet been archaeologically proven.
The circumference of the ancient reservoir Kalawewa, which is functional again, is now over 60 km. Depending on the water levels, it usually covers an area of 18 square kilometers (7 square miles). The Kalawewa is still not the largest of the reservoirs of the Anuradhapura period. But it was in a sense the heart of the ancient irrigation network, one of the most astonishing achievements of the hydraulic civilizations of Asia. The Kalawewa was the most important water distributor for many other reservoirs and is again today. Before the construction of the Kalawewa, only the water from the Malwattu Oya river system, which runs through the central former royal land "Rajarata", which is today's cultural triangle, was used for irrigation of the cultivated area around Anuradhapura. However, the southern Kala Oya river, which rises on the northern edge of the mountains, is richer in water than the said Malwattu Oya. Damming the Kala Oya potentially led to more than doubling the amount of water available, at least if its water could be diverted to the Anuradhapura area. And that's exactly what the Jayaganga Canal was used for, an artificial drainage of the Kala Oya waters from the Kalawewa towards the north to the tanks at Anuradhapura. The Jayaganga Canal was therefore an integral part of Dhatusena's Kalawewa project. Another drainage canal drained water westwards to the Siyambalagamuwa Reservoir, which fed 30 other tanks of smaller size.
There are ancient reports that even another mountain river beyond the main watershed, the Amban Ganga, was tapped for the Kalawewa by digging a tunnel to the Minisgoni Oya, which is a second river feeding the Kalawewa. However, such a tunnel has not yet been archaeologically proven.
for more information about the history of irrigation in Sri Lanka please click here...
There might have been around 11,000 ancient reservoirs of various sizes in the area around Anuradhapura, and 30,000 throughout Sri Lanka. The Sinhalese name for reservoir is Wewa. The British called them tanks. Some bear the Tamil name Kulam. Kulam is also the name of the reservoirs in southern India. They existed there earlier than in Sri Lanka, and one can assume that the irrigation culture of the Sinhalese was inspired by that of the neighbouring South Indian Tamils. However, Sri Lanka's dam projects far exceeded those in southern India, both in the size of the artificial lakes and in the scale of their interconnections to form a large-scale irrigation system. The fact that the South Indian Tamils did not develop something like this has a natural background. They live in a similarly dry region as the Sinhalese of the Cultural Triangle, namely in the lee of the mountains, with little rainfall. But far more river water flows down from those mountains into their cultivated area. Several particularly large rivers form large river oases in Tamil Nadu, southern India. The irrigation technology of the South Indian Tamils was therefore less concerned with creating large water reservoirs than with distributing the water through canals directly from the rivers into the wide plain, and with taming these rivers, which annually rose in threatening way due to the monsoon rainfalls. Similar to ancient China, the major achievements of South Indian Tamils in irrigation management are dams along the river banks instead of large-scale dams for reservoirs.
However, the Sinhalese civilization enjoyed great prestige with its dam projects. A delegation came to Sri Lanka from the other end of the subcontinent, from Kashmir, to learn about irrigation techniques.
The rivers of the Cultural Triangle were not such powerful watercourses that the region had to be protected from the force of floods. The opposite problem existed here: the amounts of water were not sufficient. When the precipitation was high in the rainy season, there was enough water available directly from the rivers for agriculture. But even small groups of settlers may have had problems with their food supply at the beginning of the island's colonization. In the areas they inhabit, water is available in some watercourses only every six months, which is usually enough for one harvest of rice per year. However, the winter monsoon rainfall sometimes failed to materialize, meaning that one year's rice harvest could fall out entirely. And in the annual dry seasons, water became scarce, so that the natural water resources were inadequate for a growing population.
That's why the immigrant Sinhalese built small reservoirs based on the model of the Tamil kulams. Soon after settling on the island in the 5th or 4th century BC, the construction of reservoirs began. They had to be built by village communities in collaboration and, above all, the villagers also had to look after and maintain them. The tanks were used by village communities to distribute water throughout the year. But that alone did not completely solve the natural problem. As mentioned, once or twice a decade there could be no rainfall at all during an entire year. These years of consistently low water levels could not be overcome with small reservoirs alone. That is why the priority national task was to build larger tanks with greater capacity for such years if crisis. With regard to the Kalwewa, Chulavansa verse 38,41 writes about Dhatusena: "By damming the great rivers he created fields that were continually watered."
The large feeder tanks, called Dana Vapis, were able to adequately supply the smaller, locally maintained reservoirs, especially during long dry periods. At the instigation of - therefore important - kings such as Mahasena and Dhatusena for Anuradhapura and especially Parakramabahu for Polonnaruwa, gigantic dam projects were added, from which smaller systems were fed. What was particularly important was that additional water resources were tapped with the help of long canals, namely from larger permanently flowing rivers further south. The Kalawewa is a prime example of this. King Mahasena's older Minneriya tank already fulfilled a similar function for the area beyond the main watershed. Step by step, a large-scale network of royal giant reservoirs with interconnected medium-sized and small municipal reservoirs emerged in Sri Lanka.
The Wewas of various sizes were built in Sri Lanka over the course of 1,500 years until the end of the Polonnaruwa period in the 13th century. The dry regions in the north and east that were thereby developed, were the islands most populous regions those days. When the population in these areas declined dramatically in the 13th century, the ancient wewas fell into disrepair. It was only in the 19th century that the British administration tried to use some of them for cultivation puposes agan. Today, around tanks 7,000 are in use again in Sri Lanka. Even in ancient times, all 30,000 Wewas were never functional at the same time, but from the 3rd century onwards there were probably more than today.
Most Wewas were small village tanks, called Grama Vapis. In the dry zone agricultural area there was an average of about one Wewa per square kilometer. These Wewas were staggered one behind the other. Along natural watercourses there were rows of tanks with their respective irrigated paddy fields. This is called a cascade system. It’s confined to one river system, whereas large projects such as the canal of Yoda Ela fed by the Kala Wewa, crossing the watershed of two river systems, forms a so-called trans-basin system.
The Wewas served other purposes besides irrigation. They served as bathing and washing facilities for the villagers. In many parts of Sri Lanka they continue to be used in this way by families who do not have private bathrooms. They also had a microclimatic cooling effect. New species of animals and plants settled on its shallow banks. In this way, new biotopes were created and there was also a greater wealth of useful plant species.
The Wewas were the basis of the ancient Sinhalese civilization of Sri Lanka. Those ancient mile-long dams with regulation locks and canals with minimal gradient angles are considered works of genius in engineering even by today's standards, requiring extraordinary skills in surveying and planning. The ancient irrigation system is, rightly so, a source of pride of the Sinhalese people. Artificial irrigation had already existed in northern India's river plains and, as already mentioned, as village communities' reservoirs in southern India, but a comprehensive network that turned steppe zones into fertile lands for more than a millennium - much more fertile than today - is unique in South Asia. Only in the Middle Ages, corresponding Sri Lanka’s late Anuradhapura and the subsequent Polonnaruwa periods, developments on a similar scale appear in rice-growing cultures of Souheast Asia, viz. in Burma and Cambodia, which, like those in Sri Lanka, fell into disrepair somewhat before the arrival of the Europeans.
The construction and maintenance of these large facilities was, in addition to the patronage of the Buddhist Order, the main duty of the kings of Sri Lanka, but also one of their main sources of income. They collected water fees from the municipalities. Incidentally, the king's agricultural and religious tasks were intertwined, which can be seen from the fact that water and fertility symbolism occupies such a prominent place in Sri Lanka's Buddhist art. However, the political doctrine of the Buddhism obliged the king to care for the well-being of his subjects, and that explicitely meant providing water, not just building temples. On the other hand, the king also transferred water management functions to the Buddhist Order. Not only was land donated to the Sangha to ensure its sustenance, several donations for the Buddhist Clergy also consisted of water tanks along with the income from the water fees, which other users of the water then had to pay to the order. With their additional sources of income generated from water supply, the monasteries also took on the task of maintaining the irrigation systems. Due to this delegation of irrigation work to lower authorities - monasteries, regional princes or village communities - the Sinhalese culture was able to endure weak kings at the top of the state and many invasions and civil wars. A few really powerful kings, each about a century apart, were sufficient to organize the constructions of giant dams for the large feeder tanks. The local population could then take care of the subsequent maintenance on their own.
However, the Sinhalese civilization enjoyed great prestige with its dam projects. A delegation came to Sri Lanka from the other end of the subcontinent, from Kashmir, to learn about irrigation techniques.
The rivers of the Cultural Triangle were not such powerful watercourses that the region had to be protected from the force of floods. The opposite problem existed here: the amounts of water were not sufficient. When the precipitation was high in the rainy season, there was enough water available directly from the rivers for agriculture. But even small groups of settlers may have had problems with their food supply at the beginning of the island's colonization. In the areas they inhabit, water is available in some watercourses only every six months, which is usually enough for one harvest of rice per year. However, the winter monsoon rainfall sometimes failed to materialize, meaning that one year's rice harvest could fall out entirely. And in the annual dry seasons, water became scarce, so that the natural water resources were inadequate for a growing population.
That's why the immigrant Sinhalese built small reservoirs based on the model of the Tamil kulams. Soon after settling on the island in the 5th or 4th century BC, the construction of reservoirs began. They had to be built by village communities in collaboration and, above all, the villagers also had to look after and maintain them. The tanks were used by village communities to distribute water throughout the year. But that alone did not completely solve the natural problem. As mentioned, once or twice a decade there could be no rainfall at all during an entire year. These years of consistently low water levels could not be overcome with small reservoirs alone. That is why the priority national task was to build larger tanks with greater capacity for such years if crisis. With regard to the Kalwewa, Chulavansa verse 38,41 writes about Dhatusena: "By damming the great rivers he created fields that were continually watered."
The large feeder tanks, called Dana Vapis, were able to adequately supply the smaller, locally maintained reservoirs, especially during long dry periods. At the instigation of - therefore important - kings such as Mahasena and Dhatusena for Anuradhapura and especially Parakramabahu for Polonnaruwa, gigantic dam projects were added, from which smaller systems were fed. What was particularly important was that additional water resources were tapped with the help of long canals, namely from larger permanently flowing rivers further south. The Kalawewa is a prime example of this. King Mahasena's older Minneriya tank already fulfilled a similar function for the area beyond the main watershed. Step by step, a large-scale network of royal giant reservoirs with interconnected medium-sized and small municipal reservoirs emerged in Sri Lanka.
The Wewas of various sizes were built in Sri Lanka over the course of 1,500 years until the end of the Polonnaruwa period in the 13th century. The dry regions in the north and east that were thereby developed, were the islands most populous regions those days. When the population in these areas declined dramatically in the 13th century, the ancient wewas fell into disrepair. It was only in the 19th century that the British administration tried to use some of them for cultivation puposes agan. Today, around tanks 7,000 are in use again in Sri Lanka. Even in ancient times, all 30,000 Wewas were never functional at the same time, but from the 3rd century onwards there were probably more than today.
Most Wewas were small village tanks, called Grama Vapis. In the dry zone agricultural area there was an average of about one Wewa per square kilometer. These Wewas were staggered one behind the other. Along natural watercourses there were rows of tanks with their respective irrigated paddy fields. This is called a cascade system. It’s confined to one river system, whereas large projects such as the canal of Yoda Ela fed by the Kala Wewa, crossing the watershed of two river systems, forms a so-called trans-basin system.
The Wewas served other purposes besides irrigation. They served as bathing and washing facilities for the villagers. In many parts of Sri Lanka they continue to be used in this way by families who do not have private bathrooms. They also had a microclimatic cooling effect. New species of animals and plants settled on its shallow banks. In this way, new biotopes were created and there was also a greater wealth of useful plant species.
The Wewas were the basis of the ancient Sinhalese civilization of Sri Lanka. Those ancient mile-long dams with regulation locks and canals with minimal gradient angles are considered works of genius in engineering even by today's standards, requiring extraordinary skills in surveying and planning. The ancient irrigation system is, rightly so, a source of pride of the Sinhalese people. Artificial irrigation had already existed in northern India's river plains and, as already mentioned, as village communities' reservoirs in southern India, but a comprehensive network that turned steppe zones into fertile lands for more than a millennium - much more fertile than today - is unique in South Asia. Only in the Middle Ages, corresponding Sri Lanka’s late Anuradhapura and the subsequent Polonnaruwa periods, developments on a similar scale appear in rice-growing cultures of Souheast Asia, viz. in Burma and Cambodia, which, like those in Sri Lanka, fell into disrepair somewhat before the arrival of the Europeans.
The construction and maintenance of these large facilities was, in addition to the patronage of the Buddhist Order, the main duty of the kings of Sri Lanka, but also one of their main sources of income. They collected water fees from the municipalities. Incidentally, the king's agricultural and religious tasks were intertwined, which can be seen from the fact that water and fertility symbolism occupies such a prominent place in Sri Lanka's Buddhist art. However, the political doctrine of the Buddhism obliged the king to care for the well-being of his subjects, and that explicitely meant providing water, not just building temples. On the other hand, the king also transferred water management functions to the Buddhist Order. Not only was land donated to the Sangha to ensure its sustenance, several donations for the Buddhist Clergy also consisted of water tanks along with the income from the water fees, which other users of the water then had to pay to the order. With their additional sources of income generated from water supply, the monasteries also took on the task of maintaining the irrigation systems. Due to this delegation of irrigation work to lower authorities - monasteries, regional princes or village communities - the Sinhalese culture was able to endure weak kings at the top of the state and many invasions and civil wars. A few really powerful kings, each about a century apart, were sufficient to organize the constructions of giant dams for the large feeder tanks. The local population could then take care of the subsequent maintenance on their own.
Hydraulic Civilization - Anomaly of Ancient Sinhalese Irrigation
Sri Lanka's historians such as K.M. de Silva point to an aspect that makes the Sinhalese hydraulic engineering culture very remarkable from a cultural and historical perspective, insofar as it falls outside the framework of what is generally assumed about Asian states. As already mentioned, the Sinhalese's gigantic irrigation network was not maintained by powerful rulers with a well-ordered administrative hierarchy. The Sinhalese monarchy was usuallly rather weak and the government apparatus was only rudimentary. Instead, the operation of the irrigation system was organized independently at a lower level. As in neighbouring South India, local self-administration was strong. The example of Sri Lanka thus refutes a common thesis about the need for a central dirigiste state apparatus for the effectiveness of an agricultural culture based on large-scale irrigation. In his studies (mainly on China), Wittfogel coined the term “hydraulic culture,” which, by its very nature, is said to lead to “Asian despotism.”
In complete contrast to this, several Sri Lankan historians see the lack of an administrative hierarchy as the reason for the stability of the Sinhalese social order and the establishment of a strong central authority in the Polonnaruwas period even as one root cause of the decline of the hydraulic civilisation of Sri Lanka in the following 13th century, for the following reason: When the Polonnaruwa king Parakrambahu I centralized all responsibilities and thus disempowered the former regional principalities in the south and west, the monasteries, the nobility in the capital and core region and the village communities, they were no longer able to organize the maintenance of the irrigation facilities themselves as soon as the king's strong hand fell away again. Actually, there had also been many devastating wars in the preceding Anuradhapura period, but the hydraulic system remained intact because the events at the top of the state did not fully penetrate the regions.
In complete contrast to this, several Sri Lankan historians see the lack of an administrative hierarchy as the reason for the stability of the Sinhalese social order and the establishment of a strong central authority in the Polonnaruwas period even as one root cause of the decline of the hydraulic civilisation of Sri Lanka in the following 13th century, for the following reason: When the Polonnaruwa king Parakrambahu I centralized all responsibilities and thus disempowered the former regional principalities in the south and west, the monasteries, the nobility in the capital and core region and the village communities, they were no longer able to organize the maintenance of the irrigation facilities themselves as soon as the king's strong hand fell away again. Actually, there had also been many devastating wars in the preceding Anuradhapura period, but the hydraulic system remained intact because the events at the top of the state did not fully penetrate the regions.
for more information about the specifics of Sri Lanka's hydraulic civilization please click here...
Not only did the village level play an independent role, but there were also fewer class differences in the countryside than in other parts of Asia or in feudal Europe. In remote regions of Sri Lanka, relatively egalitarian village communities at ancient Wewas have survived to the present day.
However, when the system fell into the hands of an oriental despot with a pronounced hierarchical administration under Parakramabahu the Great the irrigation economy also collapsed shortly afterwards along with the state control. The irrigation system fell into disrepair and the population declined dramatically in the century after Parakramabahu. The thirteenth century marked the deepest turning point in the country's history, even more lasting than the arrival of the Europeans. The millennium and a half of civilizational prosperity without strong central authority and without hierarchical administration on the one hand and, on the other hand, the cultural decline as a result of centralization - both of these are exactly the opposite of the theory of "Asian despotism", that assumes stability and hierarchal and centralized structures as needs of an irrigation economy.
The first well-known researcher who firmly rejected the Wittfogel thesis of "Asian despotism" in empirical studies for Sri Lanka was another European named Edmund Leach. With his study "Hydraulic Society in Ceylon" from 1959, he became a pioneer in the social history of ancient Sri Lanka. The qualified electrical engineer had worked for a British trading company in China for many years. During his many travels there, he also came into contact with the Yami people on the "orchid island" of Lanyu, southeast of Taiwan. He was so fascinated by the Yami that he decided to study anthropology. Later on, he had to stop research in Iraq due to the security situation there. Instead, he wrote his dissertation on the social structure of the Kachin minority in Burma. Because of the chaos of war in Burma, he did not publish his research results until 1954. This work, “Political Systems of Highland Burma,” became a classic of cultural anthropology. It broke with the assumption of a temporally static social structure in agricultural societies and also with the cliché that despotisms with hierarchies ruled in Asia. Rather, Leach stated that for structural (inheritance) reasons, Kachin society was in a periodic transition between a hierarchical and an egalitarian social order, whereby the hierarchical order that regularly re-emerged was originally adopted from the neighbouring Shan, but could never finally prevail. It was always pushed aside for a certain time by a recurring egalitarian structure. Leach's thesis, initially no less surprising, that Sri Lanka's gigantic irrigation system developed largely without any significant administrative hierarchy has since been confirmed in many studies.
The British colonial rulers, however, organized irrigation in a centralized way. The governments of independent Sri Lanka also relied on the construction of large reservoirs to develop new agricultural land. But the major projects alone did not achieve the set goals. Therefore, additional efforts were being made to promote the expansion of small or medium-sized reservoirs, particularly through the repair of a further 10,000 ancient tanks. This new concept was based on the ancient model in village cooperation. Agriculture Minister Dissanayake said in an interview in June 2008: It is not entirely correct to use the term 'tank' for a Wewa, because it is not simply a place where water is collected, but a social-environmental system. And: Our strategy is not to conclude contracts with investors, but to engage the villagers with sponsorship from the government. The main reason for this is that they are the ones who know which path the water takes, in which direction it should be diverted and what the suitable catchment areas are. Even in the distant past, the Wewas were built and protected by the villagers.
However, when the system fell into the hands of an oriental despot with a pronounced hierarchical administration under Parakramabahu the Great the irrigation economy also collapsed shortly afterwards along with the state control. The irrigation system fell into disrepair and the population declined dramatically in the century after Parakramabahu. The thirteenth century marked the deepest turning point in the country's history, even more lasting than the arrival of the Europeans. The millennium and a half of civilizational prosperity without strong central authority and without hierarchical administration on the one hand and, on the other hand, the cultural decline as a result of centralization - both of these are exactly the opposite of the theory of "Asian despotism", that assumes stability and hierarchal and centralized structures as needs of an irrigation economy.
The first well-known researcher who firmly rejected the Wittfogel thesis of "Asian despotism" in empirical studies for Sri Lanka was another European named Edmund Leach. With his study "Hydraulic Society in Ceylon" from 1959, he became a pioneer in the social history of ancient Sri Lanka. The qualified electrical engineer had worked for a British trading company in China for many years. During his many travels there, he also came into contact with the Yami people on the "orchid island" of Lanyu, southeast of Taiwan. He was so fascinated by the Yami that he decided to study anthropology. Later on, he had to stop research in Iraq due to the security situation there. Instead, he wrote his dissertation on the social structure of the Kachin minority in Burma. Because of the chaos of war in Burma, he did not publish his research results until 1954. This work, “Political Systems of Highland Burma,” became a classic of cultural anthropology. It broke with the assumption of a temporally static social structure in agricultural societies and also with the cliché that despotisms with hierarchies ruled in Asia. Rather, Leach stated that for structural (inheritance) reasons, Kachin society was in a periodic transition between a hierarchical and an egalitarian social order, whereby the hierarchical order that regularly re-emerged was originally adopted from the neighbouring Shan, but could never finally prevail. It was always pushed aside for a certain time by a recurring egalitarian structure. Leach's thesis, initially no less surprising, that Sri Lanka's gigantic irrigation system developed largely without any significant administrative hierarchy has since been confirmed in many studies.
The British colonial rulers, however, organized irrigation in a centralized way. The governments of independent Sri Lanka also relied on the construction of large reservoirs to develop new agricultural land. But the major projects alone did not achieve the set goals. Therefore, additional efforts were being made to promote the expansion of small or medium-sized reservoirs, particularly through the repair of a further 10,000 ancient tanks. This new concept was based on the ancient model in village cooperation. Agriculture Minister Dissanayake said in an interview in June 2008: It is not entirely correct to use the term 'tank' for a Wewa, because it is not simply a place where water is collected, but a social-environmental system. And: Our strategy is not to conclude contracts with investors, but to engage the villagers with sponsorship from the government. The main reason for this is that they are the ones who know which path the water takes, in which direction it should be diverted and what the suitable catchment areas are. Even in the distant past, the Wewas were built and protected by the villagers.
Technological Achievements of Ancient Sri Lankan Irrigation
The historical structures of a Sinhalese reservoir always include three structures: the dam, a drain and an overflow device.
A dam is called "Wawkandiya" in Sinhalese, which means "built mountain". The core of a dam was made of clay of greater impermeability, the mantle of semi-permeable clay or, at the back, of bare soil planted with grass to minimize erosion by rain. To prevent water seepage, reinforcements were made parallel to the embankment on the water side with dense clay inserted, which was tamped firmly by elephants. In sensitive areas of the surface on the water side, the embankment was paved with stones. This stone bowl, called "Ralapanawa", was intended to prevent erosion caused by waves, which can otherwise quickly occur in large tanks. In addition, in many Wewas and especially in Kalawewa, natural rock ridges were used and the dam line was even based on the longitudinal extent of wide rocks.
The five kilometer long earth dam of the Kalawewa is over 20 m high in some places, with a base width of over 60 m. There are no narrow river valleys in the flat area of the Cultural Triangle. That’s why dams of such enormous lengths and very sophisticated land surveying techniques were required to achieve the goal of determining the optimal position of a dam for the desired water capacity with the least possible construction effort.
A dam is called "Wawkandiya" in Sinhalese, which means "built mountain". The core of a dam was made of clay of greater impermeability, the mantle of semi-permeable clay or, at the back, of bare soil planted with grass to minimize erosion by rain. To prevent water seepage, reinforcements were made parallel to the embankment on the water side with dense clay inserted, which was tamped firmly by elephants. In sensitive areas of the surface on the water side, the embankment was paved with stones. This stone bowl, called "Ralapanawa", was intended to prevent erosion caused by waves, which can otherwise quickly occur in large tanks. In addition, in many Wewas and especially in Kalawewa, natural rock ridges were used and the dam line was even based on the longitudinal extent of wide rocks.
The five kilometer long earth dam of the Kalawewa is over 20 m high in some places, with a base width of over 60 m. There are no narrow river valleys in the flat area of the Cultural Triangle. That’s why dams of such enormous lengths and very sophisticated land surveying techniques were required to achieve the goal of determining the optimal position of a dam for the desired water capacity with the least possible construction effort.
for more information about the ancient irrigation technology please click here...
The Nuwara Wewa on the outskirts of Anuradhapura has an even higher dam than the Kalawewa. The longest dam of an ancient reservoir in Sri Lanka is that of the Yodawewa ("giant tank") in the hinterland of the port city of Mannar, northwest of Anuradhapura. Its dam is over eleven kilometers long. It is also a legacy of King Dhatusena’s reign. Here the British considered the dam to be too wide and too elaborately protected on the sides. It was only later that the reason for the dimensioning was recognized, namely that the water near the coast had to be distributed across an enourmous width.
The spillway is called Pitawana. It is used to divert flood water that must not pass over the top of the dam, otherwise the earth dam itself would be weakened and thus damaged. The overflow is located in the direction of the natural river bed, in the case of the Kalawewa in a northwesterly direction. A Pitawana is not made of earth like the rest of the dam, but, since it cannot suffer from regular flooding, it is made of huge granite slabs that are hewn in such a way that they fit together precisely. The spillway of the Kalawewa is over 50m long. During their efforts to restore the ancient Kalawewa for the renewed cultivation of the dry area, the British administrative expert George Turnour (1799-1843), who became known as the first translator of Buddhist writings in Ceylon, considered such a wide drainage spillway to be oversized, he called the Pitawana of the Kalawewa one of the island's most colossalmonuments to wasted labor. British engineers expressed similar sentiments. They were soon proven wrong. Under rare but recurring extreme weather conditions, the dammed Kala Oya river can have much higher flooding in some monsoon seasons than the other rivers in the Cultural Triangle. The vast ancient Pitawana system proved to be precisely adapted to such extreme floods. Not only will larger amounts of water arrive, but they will also rise more quickly. This unusually wide Pitawana drain was then required to quickly drain away the excess water.
The third element of the tank system is the drainage for irrigation, which is the essence of the entire damming project. In the case of the Kalawewa, there are several such drains, the main one leading north to Anuradhapura is the Yoda Ela, as mentioned above.
In the smallest village wewas, drainage was simply cut into the dam at the desired location for a certain period of time and then repaired. Other small wewas had permanent tunnels in the dam near the base, often reinforced by a hollow log through which water could then flow. Such tunnels could be closed with simple flaps, which were perhaps sealed with clay, but this only worked if the water pressure was not too high, i.e. if the tanks were not very deep.
The more sophisticated sluice gate systems of the reservoirs with higher dams were called Sorowwas (or Horowwas according to the older spelling). Three types of locks or sluice gates were known. The Ketasorovwas consisted of outflow pipes reinforced with terracotta. They were not sealed, but were only given water as needed. Ketasorovwas are tube locks that regulate the flow of water by the depth of the tube entrance below the water level. Greater depth means more pressure and therefore faster water flow. Stopping the flow of water can be easily accomplished by lifting the pipe entrance above the surface of the water. In today's locks of this type, this is accomplished simply by lifting an elastic tubular material. Since the ancient Sinhalese had not invented plastic, of course, they used a different method. The pipe always looked out from the surface of the water, but it could be opened laterally by raising side inlets at different depths. Such locks were used on medium-sized tanks. The Rajamohols are piston locks. With them, a locking device is inserted in front of or into the flow tube from above. Rajamohol locks are known from India but have not been documented in Sri Lanka.
The Sinhalese invented a technical innovation for the large tanks, a kind of valve pipe, which is called Bisokotuwa. There is a vertical, open-topped shaft in the earthen dam that reaches down to the water pipe. The water then flows through the bottom of this shaft. In other words: One pipe brings water into the shaft, another pipe takes water out of it at the same height on the opposite side of the shaft. This latter output pipe can be closed in the shaft by a wooden plate as a valve flap, which is folded up and down by a lifting device. If this stone valve flap is folded down, it closes the exit. The trick here is that the valve flap is easier to handle than piston locks; it can be opened without much effort using a simple lifting device. This technique is a Sinhalese invention. Until then they were not known in other advanced cultures. Such valve pipes appeared in Europe in the 18th century. The Bisokotuwa sluice type was developed in Sri Lanka around the year 300, in connection with the large tanks of King Mahasena. Bisokotuwas were used on tanks with a dam height of more than 10 m.
King Dhatusena's Kalawewa not only supplied 60 village tanks in the area, but his main task, as mentioned, was to develop the Kala Oya River to supply water to the greater Anuradhapura area, the main settlement area of the Sinhalese. For this purpose he built an irrigation canal that required hardly less labor than the Kalawewa itself.
The 86 kilometer long and 12m wide Jayaganga drainage canal is also known as Yoda Ela, see above. (Ganga means stream, Ela means canal.) It is a masterpiece of ancient engineering. In the first 27 kilometers its gradient is only ten centimeters per kilometer, in the lower part it is two centimeters. This is admirable precision even by the standards of today, which can work with laser measurement technology. The low flow speed made it possible to forego a paved floor. The water flows over natural ground. A further significant reduction in costs and labor was achieved by the fact that, as with many other irrigation canals in Sri Lanka, the natural slopes of the ground were used for the course of the canal in such a way that it runs along virtually its entire length along a dam on only one of the two sides. So only one artificial dam is required to keep the water in the canal, the other side of the canal is formed by the natural slope.
When repairing the Jayaganga, the engineers discovered something that they had encountered in many places in Sri Lanka since the British colonial era: When they used their modern measuring technology to locate suitable locations for locks, they came across remnants of ancient locks during the construction works. For example, an official named Balfour reports: When I was in charge of these works some years ago, I planned a new lock on the Jaya Ganga and fixed its position according to modern ideas. Later, while excavating for the foundations, we came across the ruins of an old lock. This showed that the engineers of fifteen hundred years ago had exactly the same ideas. In another case, the British diverted water from the Jayaganga with a new side canal because they wanted to use it to open up a certain area for agriculture. Then their archaeologists discovered that an ancient side canal took exactly the same route, anywhere within a few meters along the route of the newly planned canal.
The Jayaganga supplies water in particular to the Tissawewa a few kilometers southwest of the ancient city of Anuradhapura, but the canal branches before reaching the Tissa Wewa and also carries water to the Nacchaduwa reservoir southeast of Anuradhapura, which, by the way, is passed along if you use the shortest road connection from Anuradhapura to Kalawewa. The Nachchaduwa-Wewa, which itself is as gigantic as the Kalawewa, dams the main river of the cultural triangle, the Malwattu Oya, upstream of Anuradhapura, and supplies other reservoirs in the immediate vicinity of this former capital, especially Anuradhapura's largest reservoir, the Nuwara Wewa on the eastern outskirts of the city.
The spillway is called Pitawana. It is used to divert flood water that must not pass over the top of the dam, otherwise the earth dam itself would be weakened and thus damaged. The overflow is located in the direction of the natural river bed, in the case of the Kalawewa in a northwesterly direction. A Pitawana is not made of earth like the rest of the dam, but, since it cannot suffer from regular flooding, it is made of huge granite slabs that are hewn in such a way that they fit together precisely. The spillway of the Kalawewa is over 50m long. During their efforts to restore the ancient Kalawewa for the renewed cultivation of the dry area, the British administrative expert George Turnour (1799-1843), who became known as the first translator of Buddhist writings in Ceylon, considered such a wide drainage spillway to be oversized, he called the Pitawana of the Kalawewa one of the island's most colossalmonuments to wasted labor. British engineers expressed similar sentiments. They were soon proven wrong. Under rare but recurring extreme weather conditions, the dammed Kala Oya river can have much higher flooding in some monsoon seasons than the other rivers in the Cultural Triangle. The vast ancient Pitawana system proved to be precisely adapted to such extreme floods. Not only will larger amounts of water arrive, but they will also rise more quickly. This unusually wide Pitawana drain was then required to quickly drain away the excess water.
The third element of the tank system is the drainage for irrigation, which is the essence of the entire damming project. In the case of the Kalawewa, there are several such drains, the main one leading north to Anuradhapura is the Yoda Ela, as mentioned above.
In the smallest village wewas, drainage was simply cut into the dam at the desired location for a certain period of time and then repaired. Other small wewas had permanent tunnels in the dam near the base, often reinforced by a hollow log through which water could then flow. Such tunnels could be closed with simple flaps, which were perhaps sealed with clay, but this only worked if the water pressure was not too high, i.e. if the tanks were not very deep.
The more sophisticated sluice gate systems of the reservoirs with higher dams were called Sorowwas (or Horowwas according to the older spelling). Three types of locks or sluice gates were known. The Ketasorovwas consisted of outflow pipes reinforced with terracotta. They were not sealed, but were only given water as needed. Ketasorovwas are tube locks that regulate the flow of water by the depth of the tube entrance below the water level. Greater depth means more pressure and therefore faster water flow. Stopping the flow of water can be easily accomplished by lifting the pipe entrance above the surface of the water. In today's locks of this type, this is accomplished simply by lifting an elastic tubular material. Since the ancient Sinhalese had not invented plastic, of course, they used a different method. The pipe always looked out from the surface of the water, but it could be opened laterally by raising side inlets at different depths. Such locks were used on medium-sized tanks. The Rajamohols are piston locks. With them, a locking device is inserted in front of or into the flow tube from above. Rajamohol locks are known from India but have not been documented in Sri Lanka.
The Sinhalese invented a technical innovation for the large tanks, a kind of valve pipe, which is called Bisokotuwa. There is a vertical, open-topped shaft in the earthen dam that reaches down to the water pipe. The water then flows through the bottom of this shaft. In other words: One pipe brings water into the shaft, another pipe takes water out of it at the same height on the opposite side of the shaft. This latter output pipe can be closed in the shaft by a wooden plate as a valve flap, which is folded up and down by a lifting device. If this stone valve flap is folded down, it closes the exit. The trick here is that the valve flap is easier to handle than piston locks; it can be opened without much effort using a simple lifting device. This technique is a Sinhalese invention. Until then they were not known in other advanced cultures. Such valve pipes appeared in Europe in the 18th century. The Bisokotuwa sluice type was developed in Sri Lanka around the year 300, in connection with the large tanks of King Mahasena. Bisokotuwas were used on tanks with a dam height of more than 10 m.
King Dhatusena's Kalawewa not only supplied 60 village tanks in the area, but his main task, as mentioned, was to develop the Kala Oya River to supply water to the greater Anuradhapura area, the main settlement area of the Sinhalese. For this purpose he built an irrigation canal that required hardly less labor than the Kalawewa itself.
The 86 kilometer long and 12m wide Jayaganga drainage canal is also known as Yoda Ela, see above. (Ganga means stream, Ela means canal.) It is a masterpiece of ancient engineering. In the first 27 kilometers its gradient is only ten centimeters per kilometer, in the lower part it is two centimeters. This is admirable precision even by the standards of today, which can work with laser measurement technology. The low flow speed made it possible to forego a paved floor. The water flows over natural ground. A further significant reduction in costs and labor was achieved by the fact that, as with many other irrigation canals in Sri Lanka, the natural slopes of the ground were used for the course of the canal in such a way that it runs along virtually its entire length along a dam on only one of the two sides. So only one artificial dam is required to keep the water in the canal, the other side of the canal is formed by the natural slope.
When repairing the Jayaganga, the engineers discovered something that they had encountered in many places in Sri Lanka since the British colonial era: When they used their modern measuring technology to locate suitable locations for locks, they came across remnants of ancient locks during the construction works. For example, an official named Balfour reports: When I was in charge of these works some years ago, I planned a new lock on the Jaya Ganga and fixed its position according to modern ideas. Later, while excavating for the foundations, we came across the ruins of an old lock. This showed that the engineers of fifteen hundred years ago had exactly the same ideas. In another case, the British diverted water from the Jayaganga with a new side canal because they wanted to use it to open up a certain area for agriculture. Then their archaeologists discovered that an ancient side canal took exactly the same route, anywhere within a few meters along the route of the newly planned canal.
The Jayaganga supplies water in particular to the Tissawewa a few kilometers southwest of the ancient city of Anuradhapura, but the canal branches before reaching the Tissa Wewa and also carries water to the Nacchaduwa reservoir southeast of Anuradhapura, which, by the way, is passed along if you use the shortest road connection from Anuradhapura to Kalawewa. The Nachchaduwa-Wewa, which itself is as gigantic as the Kalawewa, dams the main river of the cultural triangle, the Malwattu Oya, upstream of Anuradhapura, and supplies other reservoirs in the immediate vicinity of this former capital, especially Anuradhapura's largest reservoir, the Nuwara Wewa on the eastern outskirts of the city.
King Dhatusena and the Story of Kalawewa
The repeatedly mentioned King Dhatusena is one of the great figures in the island's history simply because of the ingenious irrigation projects of his time, of which Kalawewa, Jayaganga and Yodawewa are just the most famous examples. Before him, only Vasabha in the first century AD and Mahasena in the third century AD were of similar importance to Sinhalese civilization as dam builders.
But Dhatusena is best known as the victim of parricide by Kassapa, his son with a concubine, who later built the lion fortress of Sigiriya. Kassapa, the chronicles say, had his merotorious father killed out of anger. He had asked his father to hand over his treasures, but received the answer from Dhatusena that the Kalawewa was his entire wealth. The king had invested the country's workforce and financial resources less in his private assets than in his irrigation projects. And in a figurative sense, the result was actually his wealth, namely in meritorious works, in good karma for a better rebirth. But the son felt cheated out of his inheritance. And that is why Dhatusena had to die for his great achievement, the Kalawewa.
But Dhatusena is best known as the victim of parricide by Kassapa, his son with a concubine, who later built the lion fortress of Sigiriya. Kassapa, the chronicles say, had his merotorious father killed out of anger. He had asked his father to hand over his treasures, but received the answer from Dhatusena that the Kalawewa was his entire wealth. The king had invested the country's workforce and financial resources less in his private assets than in his irrigation projects. And in a figurative sense, the result was actually his wealth, namely in meritorious works, in good karma for a better rebirth. But the son felt cheated out of his inheritance. And that is why Dhatusena had to die for his great achievement, the Kalawewa.
But the cruelty of Dhatusena’s death was the result of his previous bad karma, too: once in a rage - the ultimate Buddhist vice - he had ordered the killing of his sister and he also killed a monk who was meditating there during the construction of Kalawewa. This is the first part of the Sigiriya tragedy and is therefore one of Sri Lanka's most famous stories.
To conclude the Kalawewa description, the source is quoted below,
namely verses 38.80-114 of Wilhelm Geiger’s English translation of the Chulavansa
(The full text is available online in a pdf file at https://ia801409.us.archive.org/31/items/in.ernet.dli.2015.277108/2015.277108.699_W_O_text.pdf
To conclude the Kalawewa description, the source is quoted below,
namely verses 38.80-114 of Wilhelm Geiger’s English translation of the Chulavansa
(The full text is available online in a pdf file at https://ia801409.us.archive.org/31/items/in.ernet.dli.2015.277108/2015.277108.699_W_O_text.pdf
Dhatusena had two sons:
Kassapa by a mother of unequal birth and the mighty Moggallana by a mother of equal caste, also a charming daughter who was dear to him as his life. On his sister's son he bestowed the dignity of Senapati and gave him his daughter {to wife). Without blame (on her part) he struck her with his whip on the thigh. When the King saw the blood-stained garment of bis daughter and heard (of the affair) he in his wrath had his nephew’s mother burnt naked. From that time onward (his nephew) nursed hatred (against the king), joined Kassapa, awoke in him the desire for the royal dignity, estranged him from his father, won over his subjects and took the ruler (Dhatusena) prisoner alive. Thereupon Kassapa raised the umbrella of dominion and destroyed the people who sided with his father, having every scoundrel as his comrade. Moggallana whose intention it was to fight him, betook himself, as he could raise no forces, to Tambudipa to find troops there. Now to torment still farther the Lord of men (Dhatusena) sorely smitten as he already was by loss of his kingdom, separation from his son (Moggallana) and by life in a dungeon, the deluded (Senapati) spake thus to King Kassapa; “There are treasures lying in the King’s palace, O King, has thy father told it to thee?” On the answer “no” he said: “Knowest thou not his intention, O Monarch? for Moggallana he keeps his wealth”. When he heard that, this most wicked of men grew furious and sent messengers to his father with the command to make known the place where the treasure lay. The latter thought: this is a pretext of the villain to kill us, and he kept silence. The messengers went and told the King. He became very wroth and sent (messengers) again and again. Dhatusena thought: it is well, I will visit my friend', bathe in the Kalavapi and then die, and (he) spake to the messengers: “if he lets me go to the Kalavapi he shall learn it.” The messengers went and told the King and the King joyful in his thirst for gold, sent messengers to whom he gave a chariot with a damaged axle’. As the Monarch drove thither, the driver who guided the chariot, ate roasted corn and gave him also a little of it. He ate of it, had joy over the man and gave him a leaf for Moggallana asking him to make him gate-keeper as a reward’. Thus is good fortune fleeting as the lightning. How then can the sensible man be intoxicated by it? When the Thera heard: the King comes, he put aside the bean soup and chicken be had received remembering: the King likes that, and took his seat (awaiting the guest). The King came, greeted him respectfully and took a place at his side. Thus the twain sat side by side (joyful) as if they had gained a kingdom, and their mutual converse chased their cares away. After the Thera had entertained the King, he admonished him in many ways and encouraged him to strive ceaselessly, showing him how the world is subject to the law (of impernianency). Then Dhatusena betook himself to the tank, plunged as he liked therein, bathed and drank and spake to the King’s henchmen: “This here, my friends, is my whole wealth'”. When the King’s henchmen heard that they took him with them to the town and informed the King. The Lord of men thought: he is keeping bis treasure for his son and as long as he lives he will estrange the people of the Island from me. He was filled with fury and commanded the Senapati thus: “Slay my father." He (the Senapati) rejoiced (saying): now I have seen the back of my foe. Full of bitterness, adorned with alll his ornaments, he betook himself to the King (Dhatusena) and strutted up and down before him. When the King saw that he thought: this villain wants to ruin my soul even as my body and bring it to hell. Shall I fulfil his wish by letting anger rise within me? Awaking loving thoughts within himself, he spake to the Senapati: “I have the same feelings for thee as for Moggallana." The other laughing shook his head. When the ruler saw this he realised: today even he will slay me. Thereupon the brutal (Senapati) stripped the king naked, bound him with chains and fetters in a niche in the wall with his face outwards and closed it up with clay. What wise man seeing this would still hanker after pleasures or life or fame? The Lord of men Dhatusena went thus after 18 years, murdered by his son, to the King of the gods. When this king was building the Kalavapi tank he saw a bhikkhu sunk in meditation and as he could not rouse him out of his absorption, he had a clod of earth flung at the bhikkhu's head. The consequence of this deed experienced in his lifetime has been described (in the story of his violent death). |
“Earth thrown over the monk’s head” might sound harmless. But what is probably meant is that the king covered the monk up to his head with earth. He had him buried in the dam. Walling living people into buildings has actually occurred in South and Southeast Asia. Such reports are particularly known from Myanmar (Burma). The human sacrifice was intended to give the building a long life. It was believed that those immured in the building achieved eternal, superhuman life and then protected the structure.
Another comparable story, although a legend and not a memory of an actual human sacrifice, is also known among the Sinhalese in connection with the Kalawewa. Dhatusena is said to have appointed a man named Kadawara as overseer of the Kalawewa Dam to maintain it. One day, when water broke through at one point in the dam, Kadawara threw himself into the gap to hold back the water until his workers had closed the area again, filling the place where Kadawara was lying with soil. In this way, the overseer who sacrificed himself became a god who still watches over the dam today. He is worshiped as Kadawara Deviyo.
The fact that the Chulavamsa story of the monk covered with earth, quoted above, is less a historical report than a Buddhist legend can be seen from the multiple explicit references to karma, the basic law of existence, for which this story gives numerous examples: While the main strand of the story describes the evil repercussions of Dhatusena's previous major misdeeds, which are the karmic reason for his tragedy, the many insertions are examples of the positive effects of small good works. And that consists in sharing food. The emphasis on the gift of food is not by accident. It’s the great good deed to which Dhatusena owes the joys of kingship in the first place, because food supply is secured by the construction of the Kalawewa.
Another comparable story, although a legend and not a memory of an actual human sacrifice, is also known among the Sinhalese in connection with the Kalawewa. Dhatusena is said to have appointed a man named Kadawara as overseer of the Kalawewa Dam to maintain it. One day, when water broke through at one point in the dam, Kadawara threw himself into the gap to hold back the water until his workers had closed the area again, filling the place where Kadawara was lying with soil. In this way, the overseer who sacrificed himself became a god who still watches over the dam today. He is worshiped as Kadawara Deviyo.
The fact that the Chulavamsa story of the monk covered with earth, quoted above, is less a historical report than a Buddhist legend can be seen from the multiple explicit references to karma, the basic law of existence, for which this story gives numerous examples: While the main strand of the story describes the evil repercussions of Dhatusena's previous major misdeeds, which are the karmic reason for his tragedy, the many insertions are examples of the positive effects of small good works. And that consists in sharing food. The emphasis on the gift of food is not by accident. It’s the great good deed to which Dhatusena owes the joys of kingship in the first place, because food supply is secured by the construction of the Kalawewa.