Mullapperiyar dam issue and protection of human life.

Hydraulic Roller - The hydraulic roller is one of the most common and most lethal hazards of low-head dams. Under certain water conditions, a dangerous submerged hydraulic roller can form immediately downstream of a low-head dam.

I am from Kerala, from then called British Malabar,  In 1941 our class teacher told us about the Periyar river and how a British engineer diverted the river to flow Eastwards through the districts of the then Madras Presidency with better utilisation of the river water. The Western Ghats, also known as Sahyadri is a long range of mountains running from Gujarat in the North to Kanya Kumari in the South. On the Western side of the ranges the sea is only at a distantce 150 to 200 kilometers. The large land mass of Southern India lies to the Eastern side of the ranges. The sea is at a distance of 1500 to 2000 kilometers. Most of the rains from South-West monsoon is arrested by the Sahyadri and falls on the narrow strip of land on the Western side. But the great rivers like Mahandi, Godavari, Krishna and Kaveri flow eastwards and drain into the Bay of Bengal after a long journey making the land all along rich and fertile.

The Periyar river was falling into Arabian sea after a short journey benefitting very few people, who were otherwise getting water from the South-West monsoon. The lands to the East of the Western Ghats were dry and water scarce. The British Engineer thought that if the Periyar river was diverted towards the east by constructing a dam on the Western side, it will bring benefit to more areas of land and more people instead of wasting into the Arabian sea.

With passage of time, India became independant, linguistic states were formed and the disputes started.