The Great flood of '99 (Malayalam:'തൊണ്ണൂറ്റി ഒമ്പതിലെ വെള്ളപ്പൊക്കം' (Thonnootti Onbathile Vellapokkam) occurred when the Periyar River in Kerala state of India flooded in the month of July 1924. This happened in the year 1099 ME in the Malayalam Calendar (Kollam Era). As the Malayalam Calendar was popular in Kerala, the flood is generally referred to as "The Great flood of "99".The rain continued for about three weeks. Many districts of present-day Kerala were deeply submerged by the flood - from Thrissur, to Ernakulam to Idukki, Kottayam even up to Alappuzha and Kuttanad. A huge mountain called Karinthiri Mala 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. Various remnants of the old Railway systems still exist at Munnar. Cause Kerala state received unprecedented rains during the month of July 1924. Kerala received 3,368 mm of rain during the monsoon season (June to September), 64 percent higher than normal and is the highest recorded rainfall. The flood was probably caused by offshore vortices along the west coast and perturbations higher up in the troposphere and is not attributed to any depression or cyclonic disturbance in the Arabian sea or the bay of Bengal. The rivers in the state were in spate and a sudden opening of the periyar sluices caused even greater misery. The restriction in flow due to swelling of the Periyar river, blockages formed by debris, changes in the river flow and other related reasons caused flooding even in places like Munnar which is 1500m above sea level. A letter from P. John John, owner of tea estates, to the land revenue commissioner stated: "During the last floods my tea estates, Karimkulam and Karimtharuvi, sustained heavy losses and I herewith enclose a statement showing the losses. This was mainly due to the indiscriminate working of the sluice valves of the Mullaperiyar Dam without giving any previous warning. The rainfall all over the country and especially in the Peermade District was unprecedented and the river was already in flood due to these rains and the partial opening of the sluice valves. Then it is said that