Did Ker­ala's dams ex­ac­er­bate its once-in-cen­tury floods?

The flood­ing, dubbed the worst to hit the south­ern state in nearly a cen­tury, caused bil­lions of dol­lars of dam­age to fields, homes and other in­fra­struc­ture


Joby Pathrose, a farmer liv­ing a kilo­me­tre away from the usu­ally lan­guid Peri­yar river in south­ern In­dia, was wo­ken in the night by the sound of rush­ing wa­ters. Hours later his plan­ta­tions and every­thing he owned were sub­merged.

“There was ab­so­lutely no warn­ing from the gov­ern­ment side,” said Pathrose, de­scrib­ing the dev­as­tat­ing flood­ing that hit his vil­lage of Okkal, in Ker­ala, on Au­gust 15. Pathrose says lo­cal au­thor­i­ties had ad­vised his fields were safe, de­spite the in­ces­sant rains that bat­tered Ker­ala at the peak of mon­soon.

More than 5 mil­lion peo­ple in Ker­ala were af­fected and over 200 were killed in tor­ren­tial rain and floods in Au­gust. The flood­ing, dubbed the worst to hit the south­ern state in nearly a cen­tury, caused bil­lions of dol­lars of dam­age to fields, homes and other in­fra­struc­ture.

As the rain in­ten­si­fied in mid-Au­gust state au­thor­i­ties were forced to re­lease wa­ter from 35 dams to man­age ris­ing wa­ters in reser­voirs, many of which are used to gen­er­ate hy­dro­elec­tric­ity. Pathrose and oth­ers liv­ing near the Peri­yar say the sud­den open­ing of dam gates with­out proper warn­ings to those liv­ing down­stream was a big fac­tor in the dev­as­ta­tion.

More than half a dozen ex­perts who Reuters con­sulted were di­vided on the ex­tent to which dam wa­ter spills con­trib­uted to the flood­ing, but al­most all, in­clud­ing In­dia’s Cen­tral Wa­ter Com­mis­sion (CWC), said reser­voirs lev­els were too high ahead of the dis­as­ter.

“Be­cause of this care­less­ness the dis­as­ter pro­por­tions were mul­ti­plied,” said Hi­man­shu Thakkar, co-or­di­na­tor of the South Asia Net­work of Dams, Rivers and Peo­ple (SANDRP), a non­govern­men­tal body that ad­vo­cates for bet­ter wa­ter man­age­ment prac­tices.

The re­lease of dam wa­ter, sharply crit­i­cised by some wa­ter man­age­ment ex­perts, has put a fo­cus on reser­voir op­er­a­tions and the need for bet­ter flood map­ping and warn­ing sys­tems in In­dia.

State gov­ern­ment of­fi­cials say the sever­ity of the flood­ing was due to a on­cein-a-cen­tury storm that could not rea­son­ably have been pre­pared for, and that the spilling of dam wa­ter had lit­tle im­pact.

Two largest reser­voirs in Ker­ala – Idukki and Idamala­yar – have been oper­at­ing for years with­out any emer­gency ac­tion plans, a ba­sic re­quire­ment for ma­jor dams world­wide. The reser­voirs also lack “rule curves”, an­other key safety pro­to­col that dic­tates the level of wa­ter that can safely be main­tained be­hind a dam at any point given sea­sonal fac­tors.

These pro­to­cols, while rec­om­mended by the CWC, are not yet man­dated by law. CWC says it is merely an ad­vi­sory body and it hopes a new dam safety bill, un­der fed­eral con­sid­er­a­tion, will make dam op­er­a­tors more ac­count­able.

His­tor­i­cal data shows both reser­voirs were at more than 90 per cent of their full ca­pac­ity on Au­gust 2, or more than dou­ble their 10year his­tor­i­cal av­er­ages for that time of the year.

Dam man­age­ment ex­perts who spoke to Reuters said such lev­els were dan­ger­ously high for the mid­dle of In­dia’s mon­soon sea­son.

“One of the key ad­van­tages of a dam is it can help mod­er­ate floods,” said SANDRP’s Thakkar, an engi­neer­ing grad­u­ate from the elite In­dian In­sti­tute of Tech­nol­ogy (IIT) Mum­bai. “That didn’t hap­pen as Ker­ala’s dams were al­ready full by end-July. Dams aren’t sup­posed to be full be­fore the end of the mon­soons.”

In­dia’s mon­soon sea­son runs from June through Septem­ber, and south­ern states such as Ker­ala also typ­i­cally re­ceive heavy rain in the months of Oc­to­ber and Novem­ber as mon­soon winds re­verse.

The data also shows that if the wa­ter lev­els in Idukki and Idamala­yar had been slowly low­ered to closer to their his­tor­i­cal av­er­ages in the two weeks be­fore the worst flood­ing be­gan they would have been able to ab­sorb all the rain that fell dur­ing the mid-Au­gust storm.

“The re­lease could have started ear­lier so that by Au­gust 9 there would have been left-over ca­pac­i­ties in the reser­voirs to store the wa­ter,” said Biswa­jit Mukhopad­hyay, direc­tor of wa­ter re­sources at US-based engi­neer­ing firm IEA.

NS Pil­lai, chair­man of the Ker­ala State Elec­tric­ity Board (KSEB), a state-run body that man­ages most of Ker­ala’s big dams, said that was a “highly hy­po­thet­i­cal and imag­i­nary con­clu­sion”. Heavy rain had not been fore­cast and blam­ing the dams for the flood­ing was “not jus­ti­fi­able”, he said.

Still, dozens of flood vic­tims, who live in vil­lages dot­ting the banks of Ker­ala’s big­gest river, the 244 km Peri­yar, say they faced no floods de­spite tor­ren­tial rain in late July and early Au­gust. All of them said wa­ters only rose overnight on Au­gust 15.

That was when more in­tense rain­fall forced KSEB to rapidly ramp-up re­leases of wa­ter from Idukki and Idamala­yar reser­voirs, which feed into the Peri­yar.

Wa­ter man­age­ment ex­perts note state au­thor­i­ties and the KSEB is­sued an alert on Idukki’s high wa­ter lev­els on July 31, when the reser­voir was 92 per cent full, but only be­gan a slow re­lease of wa­ter on Au­gust 9, when lev­els were at 98 per cent. Data shows Idamala­yar spills be­gan only when it ex­ceeded its full ca­pac­ity on Au­gust 9. James Wil­son, who works for the Ker­ala gov­ern­ment as spe­cial of­fi­cer on a in­ter-state wa­ter ad­vi­sory com­mit­tee, said blam­ing KSEB was un­fair, as Ker­ala’s dams only have the ca­pac­ity to store less than a tenth of the state’s an­nual rain­fall, and even less in years of ex­treme rain­fall.

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