Dating back to 1st century BCE, Anicut, Vaan, Bisokotuwa invented by ancient Sri Lankan engineers are comparable to the modern sluice, spillway and valve-pits.
The culture of Sri Lanka generally described as Sinhala Buddhist culture. Even though there are three other minor cultures that originated in the latter period. Other minority cultures on the island being identified as Tamil Hindu Culture, Christian Culture, and Muslim Culture. Sinhalese are the dominating ethnic group on the island while Buddhism being the most widely practised religion in the country.
These two domination factors (Sinhala and Buddhist) have created a separate identity to the country and its culture. These two factors have evolved together for the last two and half millennium, they are interdependent and inseparable. Due to their influence, today the religion and culture of the country are known as Sinhala Buddhist or Sinhala Buddhism.
Sinhalese considered being the first ethnic group that established a settlement in the island. These migrants came from North Indian Aryavarta, hence they belonged to Aryan stock. Historian is in the opinion of that they could be a band of the seafaring merchant, who sailed southward direction searching for a destination with luxurious merchandise such as gems, pearls etc, which had a ready demand from the upper strata of the Aryavarta society.
It is believed they settled in Sri Lanka, due to the tradition of creating new colonies in the countries they reach. According to the Sinhalavatthu, an ancient Pali chronicle originated in 3rd century AD and the records of Fa-Hien, the Chinese monk who travelled in Sri Lanka and lived for three years in 5th Century AD, there had been bands of occasional sea traders in the island and finally settled down.
The most well known and systematically narrated legend is found in the Mahawamsa, the ancient chronicle originated in 5th century AD. According to the chronicle, Vijaya and his followers of 700 people are recognized as the foundation of Sinhalese in the country.
According to Prof. S Paranawithana, the original home of Sinhalese was the upper Indus Valley. The same theory was put forward by Hsuan-Tsung, Chinese traveller who visited India in the 7th century AD. The Sinhapura from which Wijaya and his follower set sail, according to Chinese traveller, was on the River Indus, and the city was located about 117 miles on south-east direction from Taxila. The location of the original Sinhalese is in this region is supported by many archaeological findings and chronicles such as kharosthi and Lorian Tangai inscriptions. The first inscription mentions a Stupa that built covering the large surface in honour of all Buddhists. It was built by two brothers namely Sihila and Simharaksita.
After the union of Vijaya and his 700 followers with 700 brides and their retinue of one thousand families from Madurai, the capital of the Pandya kingdom, is the third wave of migrants, who settled in the island.
The early settlements in ancient Sri Lanka flourished in the areas with water resources such as rivers, tanks and lakes. The early settlers of Sri Lanka had chosen these areas in the dry zone due to the importance of water for agriculture. They came from the areas in India where the agriculture had been the main lively good. The early settlers had invented a sophisticated water management system crisscrossing the entire dry zone. The tanks, canals, and sluices of the system show the very advanced principals and techniques that are second to none even today.
Anicut, Spillway, Bisokotuwa feats of ancient engineer
Sri Lanka is the country that had the most advanced early irrigation systems in Asia. The first settlers of Sri Lanka (Indo-Aryan) possessed of high technical ability, with wide vision and a highly developed “water” and topographical sense. The vastness of conception of Ceylon’s ancient irrigation system removes all doubt that the old engineer must have depended to a critical degree on a system of levelling and horizontal measurement to render the construction practicable. Anicut, spillways and Bisokotuwa are several genius constructions of ancient engineers that worth to mention here.
Tekkan the modern Anicut
In the Anicut (tekkam) built about thirteen hundred years earlier across the Malawatu Oya to divert water to the Giant tank and in other similar contemporary structures, a cement seems to have been used. It has been proved by analytics results published in the Chemical Trade Journal that this concrete prepared and used in ancient Sri Lanka 13 centuries ago, if not earlier, showed very superior properties to the Roman mortar, which had long been accepted as the best ancient product.
The Vaan or modern spillways
The spillways, some of them man-made and called vaan in Sinhalese, other natural rock called gal-vaan, over which the waters of the tank pass when surcharged by rain in flood time, range from simple contrivances in the small tank, to complex examples which must surely have involved study of the movement of water over many years, and considerable labour to build. Two or even more spillways were sometimes provided in the larger tanks.
One of the most spectacular examples of spillways is the ancient spill-wall of chiselled granite at Kala-wewa or Kala lake, it is a stupendous construction, approximately 216 feet wide and 170 feet long, completed about the 5th century AD. The work impressively testifies to the craft of the stonemason. Each block of granite is meticulously fashioned to fit its neighbour and the whole is a wonderful monument of patient workmanship.
The Bisokotuwa or modern valve-pit
Another construction that shows a thorough knowledge of construction principal is the device known as sluice in English, and Sorowwa in Sinhala, whereby the water from the tank was led to the system of major and minor channels to be carried to fields near or far. In the smaller tanks, where pressure was by no means great, this was achieved by means of cylindrical burnt-clay pipes laid under the bund. What permitted the old-time engineer to proceed to boldly with the construction of better and bigger reservoirs was a structure found in tanks built earlier but perfected by the 3rd century AD, known as the bisokotuwa, meaning:” the enclosure where the water level lowers.” This outlet work built into the upstream face of the bund regulates or totally stopped the flow of the water into the discharge culverts, and also served as a silt trap. Engineers only surmise that the gates of this structure were of timber and that elephants furnished the motive power to lift them.
What is especially interesting is that even some of the earliest sluices are furnished with these triumphs of ingenuity which proves that the early engineers had mastered the problem so successfully that all others were content to copy their example. Thus, the builder of those Bisokotuwa has established a claim, which is 2,000 years old, to be considered the inventor of modern valve-pits and valve-towers.
Ingenious irrigation work of Sora Bora Wewa
Sora Bora Wewa or Sora Bora Lake is a classic example of the advanced engineering knowledge of ancient engineers. Especially the sluice of the lake considered to be followed the advanced engineering principals. The base of the sluice is made of a natural rock. This gigantic man-made lake is situated in the district of Mahiyangana. The lake was constructed under the reign of King Dutugemunu in the 1st Century BC. It is believed that the lake was constructed, while the young king was organizing his army in Mahiyangana. According to the historical information the waters of Loggal Oya, Ma Oya, Diyaban Oya and Dambaruwa Wewa was directed to the Sora Bora Wewa.
The lake is situated around 1.5 kilometres from the city of Mahiyangana. It is located on the Mahiyangana-Batalayaya main road. According to the folk tales the lake was constructed by the soldier, who provided the Bulath or betel leaves to the king. Since the betel leaves are called “Bulath”, the soldier was named as “Bulatha” denoting one who delivers the betel leaves.
The amount of water that can be stored in the lake is 16.89 Sq. miles and it is located well over 300 meters above the sea level. The water surface of the tank exceeds 14400 acres at the maximum capacity; its dam is 1590 feet long and 20 feet wide while the height of the dam measured to be 27.6 feet. Even today 3000 acres of lands are irrigated using the waters of Sora Bora Wewa.
Bisokotuwas was an important part of the ancient tanks, which served as the sluice. Even though Sora Bora Wewa is also an ancient tank, Sora Bora Wewa is not constructed with a Bisokotuwa. A construction similar to Bisokotuwa is constructed using granite, to control the outward water flow. The engineers opine that the ancient engineers had been able to simplify the control of outward water flow, compared to the sluice, with the invention at Sora Bora Wewa.
According to the folk stories a giant called Bulatha used to visit Mahiyangana in order to collect the Betel left required by the king. In such occasion, he had come across the region called Gonagala, where he decided to build a lake to store water. It is believed he has dislodged a mountain and large rocks to construct the lake. Today Sora Bora Wewa serves as important water storage for the people in the region. Recently the dam of the lake was reconstructed at the cost of 4.9 million rupees.
Spreading the settlements
The most important factor for selecting the places for early settlements had been the water. One of the oldest settlements of the island Thambapanni originated at the banks of Aruvu Aru. Anuradha grama evolved around Malwatu Oya, Upatissa Grama was flourished based on Kandara Oya whiles the Uruwela sprang at the mouth of Kala Oya. The settlers in Vijitha Nagar had chosen Mahaweli Ganga as their main source of water.
Digavapi was founded at the banks of Galoya, Maha Gama at the bank of Kirindi Oya, Kalyaniya at the banks of Kelani Ganga and the ancient settlement in southern Sri Lanka was founded at the mouth of Menik Ganga. As the population in Sri Lanka increased the early settler spread into the deeper parts of the country. They gradually spread into the areas such as low country wet zone, Kandy, Teldeniya, Gampola, Matale. In this manner, the settlement that originated in the dry zone had spread into the areas of the wet zone.
Population in ancient Sri Lanka
Even though the exact population of ancient Sri Lanka is not known, several historians have assumed the population by studying the historical sources such as chronicle, inscription and books. Tenants, Johnston, Denham, Primham, Pobus, Arunachalam and Surkar are some of the historians who had suggested the population in ancient Sri Lanka. It is believed that the population in the dry zone had been around 4.17 million while the population in the wet zone around 2.19 million.
The downfall of the civilization
Gigantic irrigation systems, colossal palaces and temples probably required a huge workforce in the past. Based on that the historians believe that there had a sizable population in Sri Lanka. In the later period, the sizable population of Sri Lanka was largely reduced due to the south Indian invasions. Destructing of the irrigation system and war reduced the agricultural production of the country. Malaria epidemic was another considerable factor for the destruction of