Despite heavy rains, water level in Kerala's big dams sufficiently low

Idukki Dam.

Thiruvananthapuram: Water level in 10 of KSEB's bigger dams, including the largest Idukki dam, has not crossed even the 'blue level', the first stage when a warning is issued.

No alerts have been issued for any of these 10 dams till Wednesday. This includes Sholayar, Banasurasagar, Idamalayar, Pampa and Kallar dams that played a big role in intensifying the deluge in 2018.

Idukki and Idamalayar dams alone have a storage capacity of over one billion cubic metres, which when released unplanned and in a hasty manner precipitated floods of unprecedented magnitude in 2018.

Though there has been a dramatic spurt in rainfall since the fag end of July, the water level in both Idukki and Idamalayar has not been significantly higher than the corresponding period last year. On August 2, Kerala received 70 mm rainfall, the highest for a single day this southwest monsoon season.

On that day, the water level in Idukki was 723.58 ft, which was only marginally higher than the 722.77 ft on August 2 last year. In Idamalayar, the water level on August 2 was at 157.75 ft, only slightly higher than 154.58 ft last year same time.

Even this marginal rise in water level is not a cause for worry at this moment as the levels are not high enough to issue even the lowest form of alert, the Blue Alert. At this stage, both these big dams are less than 70 per cent full. "But it is still too early to feel safe. The intensity of the rains has diminished but if it persists even at this level we might have trouble," a top KSEB official said.

The water level in Mullaperiyar, too, is far below the danger level. "Till August 10, the water level can go up to 137.5 ft but at the moment water has risen only up to 134.85 ft. As a result, there is no need to release water from Mullaperiyar," water resources minister Roshy Augustine said after a review meeting held on Wednesday.

"That there is relatively less rain in the catchment area has also helped. The inflow into the reservoir (Mullaperiyar) till evening yesterday (Tuesday) was 2,406 cubic feet per second and 1,867 cusecs of this were taken away by Tamil Nadu," the minister added.

However, water levels in seven small KSEB dams, five of them in the Idukki district, have touched the level that necessitates the sounding of the highest stage of warning, the Red Alert. Nonetheless, it is only from the Peringalkuthu reservoir in Thrissur that there is a moderate release of water, 363.11 cubic metres per second (cumecs). Top KSEB and Disaster Management Authority sources said the controlled discharge would not inundate areas lying downstream. Still, people have been shifted to camps.

Water is being discharged on the basis of what is called a 'rule curve', which was scientifically drawn up after the 2018 floods. The 'rule curve' essentially fixes the upper limit at which water level should be maintained in reservoirs every day. This preempts the panic release of water from reservoirs.

Already, there is controlled discharge from 15 of the 20 Irrigation Department dams in Kerala. Of these, only Meenkara dam in Thrissur and Mangalam dam in Palakkad seem to be filling up fast. Orange Alert, the second stage of warning, has been issued for both these dams. The Neyyar dam in Thiruvananthapuram has been issued a blue alert.

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