KSEB puts in place monsoon mgmt plan for Banasura dam

Kozhikode: Learning the right lessons from the controversy following allegations that last year’s devastating flood situation in Wayanad was worsened by the opening of shutters of Banasura Sagar Damat Padinjarathara without evacuating people downstream, Kerala state electricity board (KSEB), which manages the dam, has implemented a new set of operational procedures this monsoon.
The monsoon management plan for the reservoir includes deploying a new public warning system and maintaining water levels as per the dam specific rule curve fixed at an interval of 10 days instead of the earlier practice of waiting for the water to reach full reservoir level (FRL) before opening shutters.
Also, rainfall monitoring mechanism in the 62 sq km catchment areas will be beefed up by installing two new automated rainfall monitoring stations.
Banasura Sagar Dam authorities said that a new public alert system with sirens with a capacity to cover 5-km distance has been installed at the dam site and warning sirens will be sounded before the shutters of the dam is opened.
The revised rule curves have been set considering the inflow details and rainfall data of the last 100 years at the dam. Also, a three-colour alert system (blue, orange and red) will be issued according to the emergency level.
P Manoharan, assistant executive engineer (research and dam safety sub-division) at Banasura Sagar, said that blue alert will be issued when water reaches 1.5 metre below the rule curve level and orange alert will be issued when the water level reaches one metre below the level and the red alert will come into force when water level reaches 50 cm from the rule curve level.
As opposed to the earlier practice of allowing the water to reach the full reservoir level of 775.6 metres above mean sea level (MSL), the revised upper rule levels propose to keep the water level at/below 768 metres on June 10, 771m on July 10, 774m on August 10 and 775.6m (FRL) on November 20.
“The gate of the control shaft from Banasura Sagar to divert water for power generation will be used to control the water levels at the dam and the dam shutters will be opened if the water level crosses the rule levels fixed for that point of time,” Manoharan added.
During the last monsoon, the Banasura Sagar reservoir had been in full reservoir level from July 15 onwards and KSEB had to raise all the four shutters of the dam to record level of 290cm on August 9 following heavy inflow to the earthen dam, causing massive flooding in many downstream areas. The water from the dam had flooded houses and devoured crops in three panchayats of Padinjarathara, Kottathara and Panamaram.
The revised rule curve for Banasura Sagar Dam along with 16 other dams in the state was finalized by a committee constituted by KSEB based on the suggestions made by the central water commission.