Rains
There is fear of flooding and inundation in areas downstream with increased inflow of water into dams.
PTI/File Photo

Karnataka has been hit by heavy rains over the last couple of days, paralysing normal life in various parts of the state.

Among the various districts affected by the rains is Chikkamagaluru, where areas such as Sringeri, Balehonnur, Narasimharajapura, Mudigere, Kudhremukh and Koppa were battered by heavy showers on Wednesday.

A report by Hindustan Times states that out of the 30 districts in Karnataka, 29 of them received rainfall which is above normal level.

Reports state that the various dams along the Tunga, bhadra and Hemavathi rivers have been receiving massive inflow and that the water levels are above the danger mark.

The water levels at Linganamakki dam rose to 1785.90 feet, close to the full reservoir level of 1819 feet. While the levels at Bhadra dam was similarly high at 162.1 feet against its maximum level of 186 feet, the water level at Thunga dam has reached its maximum capacity of 588.24 feet.  

Data shows that the inflows into the Cauvery river basin has crossed 1 lakh cusecs for the first time, tweeted weather blogger Chennai Rains. With the rivers in spate, the Harangi, Hemavathi, KrishnaRajaSagara and Kabini dams of the Cauvery river basin recorded inflows of 18,300 cusecs, 28,250 cusecs, 37,000 cusecs and 46,000 cusecs respectively.

According to CNN News 18, on Wednesday the Cauvery river was flowing above the danger mark in Kodagu district. As a result, some villages were marooned in the district. The KRS Dam near Mysuru was at 113 feet, nearing the maximum level at 124 feet.

Chief Minister HD Kumaraswamy had earlier instructed officials to release Cauvery water to Tamil Nadu owing to the excessive inflows.  

Water levels in dams across Dakshina Kannada district have also reached or are nearing maximum levels.  The AMR dam has reached its maximum level of 18.9 metres, with outflows of 2100 cubic metres equal to the inflow. Outflows at Thumbe and Sagar dam shas also equalled the quantum of inflow, although the dams are yet to reach maximum level.

Flood warning to those living downstream

Speaking to TNM, Shubha Avinash, Project Scientist (Hydrology) at the Karnataka State Natural Disaster Management Centre (KSNDMC) said, “The reservoir catchment areas of all dams have been getting immense rainfall and that all this inflow will be stored in the dams.”

Each dam has a flood level, followed by a danger mark and a maximum level. Shubha explained that there is a buffer of about 2-3 metres between the flood level and danger mark in order to manage the reservoir operations.

She added, “Whatever the inflow at the moment is going above the (danger) level so all the gates will be open, which will allow the inflow to flow into the canals.”

As per the Dam Safety Protocol issued by the Central Water Commission, when the quantum of outflow from a dam is equal to the inflow, it would be considered a natural flood. However, when the quantum of outflow from a dam exceeds the inflow, it is classified as a manmade flood.

With increased inflow into the dam, there is fear of inundation and flooding in areas downstream.  Shubha said, “The Taluk officers of these areas should warn the people living in the downstream level area to move away from that area because the water will flow into these downstream areas. It is more likely that some damage will be caused to certain habitats and agricultural areas, but the people will be moved and rehabilitated to safer areas.”

Shubha said that it will take a couple of days for flooding in areas downstream to subside.