THIRUVANANTHAPURAM: As the clouds gather afresh over Kerala and Tamil Nadu under the influence of low-pressure formation over the Bay of Bengal and a cyclonic circulation over the Arabian Sea, tempers run high in Kerala as the catchment areas of Mullaperiyar dam is more prone to extreme inflows of water during the North-East monsoon season. Moreover, the cyclonic disturbance over the Bay of Bengal is critical for the Mullaperiyar dam due to its geographical features, while the Idukki reservoir usually receives heavy inflows normally during southwest monsoon periods.
James Wilson, dam safety expert and member, expert advisory group-KSEB, told The New Indian Express, “The highest inflow of water to the Mullaperiyar was witnessed in 1943 January as about 2 lakh cusecs water reached the reservoir per second. In 1989, 45,000 cusecs of water reached the reservoir per second. But the water level of the dam was relatively low then as part of the reinforcement work at the dam. Similarly, the dam witnessed heavy inflows in 1922, 1924, 1961, and even 2017," he said.
"When cyclone Ockhi, swept through coastal areas of Tamil Nadu and Kerala in November 2017, the Mullaperiyar dam witnessed seven feet increase in water level on a single night. So in the event of extreme rainfalls in the catchment areas of Mullaperiyar, anything can happen in just a few hours and the 2300 cusecs water being drawn by Tamil Nadu would be too little to control a flood situation as the inflow to the reservoir would be 10 or 20 times higher than the discharge,” he added.
When it comes to extreme rainfall events, the Indian Meteorological Department (IMD) is still unable to make accurate predictions. Not even IMD, no global weather models precisely forecast the extremely heavy rainfall in the tropical weather system. An entire weather system would change in just two to three hours in the tropical weather conditions and we have certain limitations to accurately predict cloudbursts (100 mm rain in just one hour), he added.
According to officials, at present, the situation is manageable considering the storage capacity of the Idukki reservoir and anticipated moderate spills from Mullaperiyar. But again if there are extreme rainfall events in quick intervals, things would take the worst turn in just a matter of a few hours. During the massive floods in 2018, the Mullaperiyar dam witnessed 30,000 cusecs water inflow per second. But the storage level in the dam was low then as it happened during August, said, officials.