The Great flood of '99 occurred when the River Periyar in Kerala state of India flooded in the month of July, 1924. This is the year 1099 ME in the Malayalam Calendar. As the Malayalam Calendar was popular in Kerala, this flood is generally called the flood of 99.The rain continued for about three weeks. Many districts of the present day Kerala were deeply submerged in water by this flood - From Trichur, to Ernakulam to Idukki, Kottayam even up to Alappuzha and Kuttanad. Even a huge mountain called Karinthiri Malai was washed away by this flood and the road to Munnar also went along with it. As the road to Munnar was lost by this flood, a new road from Ernakulam to Munnar became necessary - the present day road from Ernakulam to Munnar was constructed after this. Kundala Valley Railway which was the first monorail system in India was also completely destroyed.
It is a widespread belief in the old generation of Kerala that the cause of this great flood was a major breach of the Mullaperiyar Dam. That is why the flood was so powerful, even at Munnar, and tore apart even a mountain as big as Karinthiri. Old generation in the affected areas of Kerala - who are still alive - is the source of this information.
The breach of Mullaperiayr occurred 29 years after the dam was constructed. At that time, there was no other Dam in the region and there is no other possible reason that can cause such a devastating flood. Also this dam has a history of getting completely washed away twice in the flood waters during its construction.
The destructive flood claimed thousands of lives, animals and birds, and caused severe damages to the crops and property in Kerala. Most of the areas in the east while Travancore and Cochin states, parts of Malabar region were submerged under the floodwater. In Munnar around 485 cm of rain fall was reported during the flood and wide spread destruction happened. Kundala Valley Railway the narrow gauge railway line at Munnar was completely destroyed by the flood waters.