You are wrong on two aspects.
One, the article does not claim continuous functional dam although there is nothing out there to discount that. Second, you assume that the old historical dam was made functional by the British engineers is wrong. And read the below to understand how British Engineers replicated the science behind the Grand Anicut across various dams in India - some of them functioning even today.
An innovation blossom in the dust
The flow of the Kaveri, the great river of south India, is arrested at Tiruchirapalli by a stone dam built by the Chola kings in the 2nd century AD. Locally the dam is called Kallanai (Kallu=stone; anai=dam in Tamil) but it is more popularly known by the name the colonising British gave it—“Grand Anicut” (anicut is perhaps a corruption of anai=dam and kattu=build).
Grand Anicut
More technically, the anicut is not a dam, but a stone weir—a rather low structure that breaks a river into multiple streams. The Grand Anicut— a 5.4 m high wall that is 29 m long and 20 m wide—separates the Kaveri into four streams: Kollidam, Puthu Aru, Vennaru, and Kaviri.
Our story begins much later than the Cholas, however. In 1827, a 24-year old British engineer, Maj. Arthur T. Cotton, was charged with the task of inspecting the Grand Anicut.
The young engineer recommended some minor but urgent repairs to the structure, but the British Government of Madras dragged its feet. It was not until 1830 that Arthur Cotton and his younger brother and assistant, Frederick Cotton, also an engineer, were commissioned to cut sluices in the Grand Anicut so that the silt sediment would flow through.
The Madras, or the Cheap School of Engineering
Lady Hope, Arthur Cotton’s daughter recounts a memorable event in her biography of Arthur Cotton: Upon cutting the anicut, Frederick discovered a strange fact: to his amazement, he found that the Grand Anicut, “was hardly more than a mass of rubbish, mud, stones, and logs of wood, the safety of which depended solely on its then plastered surface.” As Bret Wallach sums up,
“It was an important, perhaps even a revolutionary discovery: simple inertia had been great enough to withstand 1,600 annual floods.” What is important to us today is that for Arthur and Frederick Cotton, this discovery gave rise to what they termed, “The Madras, or the Cheap School of Engineering.”
In his next project, which was to build the Coleroon Anicut slightly downstream—Coleroon was the Anglicised name for Kolidam—
Arthur Cotton applied what he had learned from the Grand Anicut: instead of a grand European style of dam, he chose a minimalist design inspired by the Grand Anicut. And we can say that he learned the lesson well for the Coleroon anicut stands even today irrigating a vast tract of about half a million acres. Some modern refurbishments had to be made over the years, and a subsequent similar dam further downstream had to be constructed when the river threatened to change course, but despite this, the Coleroon anicut is a shining example of the Madras Cheap School of Engineering.
Emboldened by his experience at replicating the design of the Grand Anicut in his work on the Coleroon anicut, Arthur Cotton used the same minimalist, resource-savvy design elsewhere. As Frederick Cotton writes, “it may be of interest to those who are following Sir Arthur in his work in Hydraulic Engineering that the most important step in his education was the lesson he learned from the builder of the so called grand anicut…it gave him, even with the slender means extended to engineers of that period, the power to control and master the greatest river of the country.”
And the greatest river Frederick Cotton is referring to here is the Godavari in Andhra Pradesh. The British estimated that the maximum discharge of the Godavari was more than 200 times the water of the Thames and 3 times that of the Nile.
Arthur Cotton took the lessons from the Kaveri and applied them in the four anicuts he built across the Godavari. Indeed, Arthur Cotton is worshipped even today by the people in Andhra Pradesh for transforming through his irrigation engineering the once-famine struck delta regions of the Godavari into the rice-bowl of India that it is today. Frederick Cotton writes about his brother:
The fact was learned from an engineer of old times, but the courage with which Sir Arthur put the idea into practice in his great works was all his own….The four anicuts he built across the Godavari are not solid masses of masonry, but surface coatings of stone over the sand of the river bed, for which he substituted cut-stone for the plaster of the early engineers, but the principles are the same. …Indeed, the cheap School of engineering, which he did much to introduce is, it appears, set aside for the extravagant system of England. And after all, what is good engineering but economy! Any engineer can do anything with money; the question is how to do great things at little cost.”
If there is one lesson that Arthur Cotton’s life and work teaches us, it is that blossoms in the dust can teach us much. The 2000-year old Kallanai across the Kaveri in Tiruchirapalli is one such blossom.
Read more:
Blossoms in the dust: (Re)covering lessons in innovation from history | Forbes India Blog