In the wake of the recent floods, dubbed the worst in a century, our objectives should be to restore confidence in the people, minimise instances of dam safety concerns like overflowing and breaches, prevent/reduce dam-induced effects of floods, redefine and put in place a revised flood warning system, dissociate dam safety from the utility concerns and empower dam safety organization.
The objectives can be achieved by a well-defined action plan for each dam. Agencies must revise Blue and Orange alert levels, which set the alarm for simultaneous inflow and safe water discharge (SWD) for optimum days to avoid water level reaching the Red alert level and return to the Orange alert level.
ldukki dam shutters had to be opened as it was not possible to accommodate the heavy water inflow in the remaining available 4-ft storage space below the full reservoir level (FRL), due to dam safety concerns.
If there was more storage space available in dams, it would have reduced/ avoided the distress discharge of up to 1500 cumecs water between Aug 15-17 from ldukki dam, along with considerably lower outflow from Edamalyar and Bhoothathankettu and thereby reduced the last mile impact of the floods.
The frantic discharge of water averted dam breaches, but has not helped alleviate the effect of the incessant rains and the resultant flood havoc. As KSEB rightly reported, they had released 525 MCM water and retained 661 MCM water from Aug 14 - Aug 19 (6 days), including the water inflow from Mullaperiyar.
A portion of the retained water gave rise to increase in storage level by 3.45 ft and the balance must have been utilised for power generation. The effort to manoeuvre the flood water around the FRL ensured dam safety at the cost of huge social and cultural crisis.
It would be interesting to know how much storage space (ft) would have been required to fill additional 525 MCM water. A hypothetical study done by the author, based on the heavy inflow between July 14 and July 17 combined with an anticipated inflow from Mullaperiyar dam, corroborates the need for a reduction in water level up to 13.5 ft below FRL.
The last mile impact on large majority of affected habitats, shops and industries was the submergence of the first floors up to 6 ft in many areas. On the other extreme, at lower plains, also due to change of river courses, there were habitats which were submerged up to 2 floors.
The need of the hour is to identify and fix an optimum reservoir level and a safe water discharge (SWD) rate to ensure quicker discharge of excess water during the periodical dry spell, after the peak periodical inflow of water.
Once the SWD is arrived at, we need to identify affected bridges, roads and villages downstream that can be temporarily affected during regulated discharges. A revised inundation map has to be developed marking the level and extent of submergence forecast. It will also necessitate rebuilding or relocating the key infrastructural facilities downstream and actions against encroachments, illegal constructions and urbanization near to the river banks.
This tragic deluge is being discarded by responsible state agencies as a flood situation that can happen in 100 or 50 years. Even if we accept this contention, India, being home to about 4,900 large dams and about 300 under construction would have seen on an average 50 to 100 dam breaches every year, which is not the case.
Due to fast growing impact of global warming, repeated instances of heavier rains, absence of better dam safety management and river management policies, floods and breaches of dams can't be ruled out in immediate proximity.
The reports on the Myanmar floods of August 29, 2018 also point to almost similar reasons wherein the incessant rains coupled with the breach of the dam at its full capacity caused huge calamities to the people and properties downstream.
Adversities of recent Chennai floods of Nov- Dec 2015 were aggravated by the opening of reservoir shutters at the last minute.
Ever increasing landslides and environmental damage to the Western Ghats owing to large-scale deforestation and the accumulation of flood waters in the backwaters of Kuttanadu have proved beyond doubt that the immediate necessity is to heed the advice of stalwarts like Madhav Gadgil and M. S. Swaminathan.
Keralites were in a comfort zone and believed we will never be bit by floods. The water level has to be maintained at lower levels for longer period of monsoon and towards the end of NE monsoon, the water level can be allowed to raise to the red alert level/FRL based on weather forecasts and disaster preparedness, thereby avoiding any revenue loss from power generation/ irrigation concerns.
Most of the dams don't have the capacity to generate power even if the water is filled up to the FRL in the SW monsoon period itself. Slush removal from the dams and replanting in catchment areas to overcome soil erosion can also help in improving the effective storage capacity.
Mr. Himanshu Thakkar, CEO of South Asia Network on Dams, Roads and People, has repeatedly expressed his concern over having dams full while the monsoon is half way. Hence, redefining and re-fixing the alert levels is a pertinent issue, as with an additional anticipated average inflow of 30 per cent to dams during the NE monsoon (Thula varsham), may lead to repeated instances when the water can quickly reach the highest levels bringing more emergency situations, dam safety concerns and panic to the people.
(The author, a Rajagiri School of Social Sciences alumnus, is management executive in the Sultanate of Oman)
