Ancient Irrigation Technology in Sri Lanka
Although many regions of the world have abundant water resources, it is a precious commodity for countries situated in deserts. In the past, people would establish their settlements near water sources or in river valleys because irrigation technology did not exist. However, during medieval times, the irrigation industry began to develop significantly.
A report by Mr. G.N. Paranavithana sheds light on the remarkable progress Sri Lanka achieved in irrigation technology during that era. He identified six irrigation construction methods: the tank method, anicut method, fountain or spring method, animal method, forest method, and earth method.
Tanks, anicuts, and fountains played major roles in promoting the irrigation industry. These systems involved building dams across rivers and streams to create reservoirs called “Wewas,” which stored and distributed water. Various technical devices such as “Biso Kotuwa,” “Ralapanawa,” “Mohola,” and “Diya keta pahana” were used for constructing and managing these tanks. These ingenious techniques showcased Sri Lanka’s exceptional irrigation technology.
Even today, numerous large-scale tanks contribute significantly to the irrigation industry. Basawakkulama, Parakcrama Samudraya, Kalawewa, and Minneriya wewa are just a few examples. Additionally, there are many small-scale tanks scattered across the country. The water collected and stored in these tanks from catchment areas is channeled through canals known as “Elas” to the arid regions of “Rajarata” and the East, where agriculture thrives. Water is also distributed to other areas as needed.
Water is released into the canals by opening the sluice gates of the tanks, and excess water is discharged using a device called “Pitawana” during the rainy season. One unique feature of these tanks is the “Biso Kotuwa,” a slit-trap that reduces water pressure. This ingenious device, exclusive to Sri Lanka’s irrigation technology, prevents damage when water flows out of the tank and waves crash against the tank bund. According to some scholars, it was named “Biso Kotuwa” because it supposedly tamed the king’s decisions, just like how the queen tempered the king’s actions.
The “Sangilikandarawa Wewa,” built in the second century BC, and the “Naachchaduwa Wewa,” built in the fifth century BC, are regarded as outstanding examples of ancient irrigation technology. H. Parker’s book, “Ancient Sri Lanka,” written in 1910, provides detailed explanations. U.B. Aushadahamy’s publication, “Wewa,” from 2003 delves into technical details related to tank systems, dams, and spillways.
In certain regions such as “Rajarata,” the East, and Magam paththuwa in the Southern Province, irrigation systems connect multiple small tanks via irrigation canals. This method allows for the irrigation of vast areas of land. The forefathers of Sri Lanka considered the extensive land when implementing these irrigation technologies.
The peak of Sri Lanka’s irrigation technology is believed to have been during the third century BC. During this period, the Sinhalese introduced techniques like conveying water through underground tunnels to higher elevations and creating artificial water reservoirs. The ability to transport water to the palace atop Sigiriya rock using air pressure, humidity, and water density astonished even modern-day scientists.
As social development and Buddhist philosophy and culture thrived, agriculture also prospered. The advancement of the irrigation industry played a crucial role in this development. The administration focused on building tanks in every village, aligning with the theme of “Tank and Pagoda, Village and Temple.”
The “Elahera” irrigation system, created by King Vasabha, serves as a prominent example of a multipurpose irrigation system. With the construction of dams across the “Amban” River, digging canals, and building tanks and dykes, sustainable agriculture was achieved in the “Rajarata” region. The Sinhalese had already established such irrigation systems thousands of years ago, long before European nations even conceived of such technologies.
There is evidence of cities adorned with picturesque ponds where people would bathe. The impure water from these ponds was also utilized for agricultural purposes. Notably, creations like the “Jaya Ganga” (Yoda ela), which ensures controlled water flow with a slope of 6 inches per mile, are marvelous. The invaders recognized that as long as these creations existed, the Sinhalese could not be defeated. Consequently, they aimed to destroy tanks and dams to disrupt agriculture and weaken the Sinhalese. However, the Sinhalese managed to endure the prolonged drought known as the “Baminitiya mahasaaya” by reviving the irrigation industry.
According to K. Daminda Namal Karunarathna’s book, “Lakdiwa Warithakshanaya” (Irrigation Technology of Sri Lanka), Sri Lankan irrigation engineers were sent to neighboring Kashmir during the reign of King Jayapida in AD 145 to assist with irrigation projects, as documented in the book “Raja Tharangani” (The History of Kashmir). From the 2nd century BC to the 13th century, Sri Lanka possessed exceptional irrigation technology. Mr. R.L. Brohiyar attests that Sri Lanka was the first country to construct tanks worldwide. Brohiyar, a British surveyor, once borrowed an ola leaf book from a temple in Kurunegala but never returned to Sri Lanka. This is how the British gained knowledge of Sri Lanka’s irrigation technology from that ola leaf book. It is said that the British took around 15,000 ola leaf books from our temples, claiming this knowledge as their own.
Considering these facts, it becomes evident that Sri Lanka held a prominent position in irrigation technology. Today, the occurrence of droughts shortly after floods can be attributed to the decline in our irrigation technology standards. One day, if our current generation absorbs the knowledge and skills of our ancestors and revitalizes the irrigation industry, Sri Lanka will proudly stand among the debtless nations of the world. Therefore, all Sri Lankans should embrace and learn the secrets and knowledge of irrigation technology for our collective advancement. It is time to initiate island-wide efforts at the village level.