Dam Induced Flood Disaster · Dams

Idukki Dam releases water when Kerala is in Floods: Could this have been avoided?

Kerala is facing serious floods. Army, Navy, NDRF, neighbouring states are all out. Dozens of people have died, landslides happening, houses washed away, the whole machinery is out to deal with the crisis.

In this flood crisis, Idukki & Idamalayar two of the Kerala’s biggest dams along with about two dozen others, are releasing water, adding to the floods and the disaster. Why are Idukki and Idamalayar, both having live storage capacity above a Billion Cubic Meters, releasing water NOW, when whole of Kerala is facing floods due to recent excessive rains? Standard excuse: The dams are full and they have no option but to release the water, they cannot store more. But why did they wait to start releasing water till the dams are full and they are faced with TINA: There is No Alternative. This love to be in TINA situation seems like a disease affecting all dam operators.


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Slideshow of screenshots showing how flood water would travel from Idukii dam to Arabian sea affecting human habitation along the course.  (Image Source: Manorama 31 July 2018) 

There are still two months of South West Monsoon for Kerala. Then large parts of Kerala also get benefits from North East monsoon that follows in Oct-Dec. In fact, the only two occasions (1981 and 1992) when the gates (shutters) of Idukki dam were opened since the Idukki Dam was commissioned in 1975, were both during North East monsoon, never in SW monsoon. The filling up of the reservoir by end of July was an unprecedented situation and KSEB, Kerala Govt and CWC should have demanded that the dam gates should be opened to release the water as soon as possible.  

So they could have easily taken advance action to release water from Idukki when Kerala was not facing floods. They obviously did not and now, when Kerala is facing floods, Idukki is adding to Kerala’s misery.

In fact, just about ten days back, on July 31, 2018[i], the media was full of stories of possible release of water with water level in Idukki crossing 2395 ft, with FRL at 2403 ft. If they had started water in the intervening relatively dry period, Idukki dam need not have added to Kerala’s flood disaster misery. They did not. WHY? Why they again waited to be in TINA state when Kerala is also facing floods?

In fact, basic objective of Idukki Dam is power generation. Idukki dam has six turbines with 130 MW capacity each. One expected that this year Idukki power generation would have broken all records, since never before has the dam water level and inflows into the dam been so high. But when one looks at daily and monthly power generation figures from National Power Portal of Central Electricity Authority (CEA) and CEA’s own past records, one is shocked to see that during June-July 2018, Idukki generated about 325 Million Units (MU) of power, which was below power generated during at least four years in just last decade: below that in 2008, 2012, 2014 and 2015. In 2014, the highest generation year for June-July, Idukki generated over 50% more than it generated in June July 2018. If Idukki had generated more power, that could have also help reduce water level.

Kerala Rivers Map by India River Forum

So why did Idukki power not generate more power when so much water was available. National Power Portal[ii] provides the answer: one of the six 130 MW units of Idukki has been under shut down since Aug 1, 2017 for Renovation/ modernisation and another 130 MW unit is under shut down since June 26, 2018 for annual maintenance. Its of course a mystery why the second unit was taken out for annual maintenance during monsoon, when it could have been done in dry season. But the consequences of this actions are that Idukki produced less power and it also added to flood disaster misery of Kerala.

In fact, even before the SW monsoon set in this year, on May 31, 2018, Idukki’s live storage capacity was 25% full, much higher than normal and higher than previous year or average of last ten years. That also contributed to the dam filling up sooner. Why such high water storage before the onset of monsoon is a question that the Idukki managers will need to answer.

Kerala Rainfall As per IMD (India Meteorology Department) figures, till Aug 9, Kerala received 20% above normal rainfall. Idukki districts tops with 50% above normal rainfall and also highest rainfall among all districts of Kerala so far: 2433.5 mm. Palakkad (44%), Kottyam (36%) and Ernakulam (33%) are some other districts having high surplus rainfall. But it’s possibly the bouts of high intensity rainfall that has created the current situation.

Performance of SW Monsoon 2018 in Kerala
Image showing overall rainfall in Kerala state so far in South West Monsoon season                 (Image source: IMD, Kerala station)

CWC has no flood forecasting sites at all in Kerala The unprecedented floods and dam water releases also raise the questions about flood forecasting and advance action by Central Water Commission (CWC), India’s only flood forecasting agency. When we see CWC’s FF website, we are shocked to find that CWC has absolutely NO flood forecasting sites, neither level forecasting, nor inflow forecasting. CWC has only flood monitoring sites in Kerala, and as the table below shows, at least one of them is non functional. Its high time that CWC includes some key dams like Idukki and Idamalayar and some key locations in its flood forecasting.

List of CWC Level Monitoring Sites, in Kerala

SN Site River Basin District HFL, M Date
1 KALAMPUR Kaliyar WFR south of Tapi Ernakulam 14.96 NA
2 RAMAMANGALAM Muvattupuzha WFR south of Tapi Ernakulam 8.42 NA
3 VANDIPERIYAR Periyar WFR south of Tapi Idukki 793.8 NA
4 NEELEESWARAM Periyar WFR south of Tapi Ernakulam 11.105 27-07-1974
5 PERUMANNU Valapatnam WFR south of Tapi Kannur 14.75 07-08-2012
6 ADKASTHALA Shiriya WFR south of Tapi Kasaragod NA NA

WFR south of Tapi

Kasaragod 19.08 12-07-1995


Meenachil WFR south of Tapi Kottayam 8.015 NA


Kuttyadi WFR south of Tapi Kozhikode 8.32 18-07-2009
10 KARATHODU Kalalundi WFR south of Tapi Malappuram 13.5 18-07-2007
11 KUNIYIL Chaliyar WFR south of Tapi Malappuram 10.63 14-07-1984
12 MANKARA Bharathapuzha

WFR south of Tapi

Palakkad 51.55          NA
13 KUMBIDI Bharathapuzha WFR south of Tapi Palakkad 9.76 18-07-2007


WFR south of Tapi Palakkad 65.55 NA
15 PULAMANTHOLE Pulanthodu WFR south of Tapi Palakkad 19.07 14-07-1994
16 THUMPAMON Pamba WFR south of Tapi Pathanamthitta 13.735 NA
17 KALLOOPPARA Pamba WFR south of Tapi Pathanamthitta 9.31 NA
18 MALAKKARA Pamba WFR south of Tapi Pathanamthitta 8.2 NA
19 PATTAZHY Kalladda WFR south of Tapi Quilon 13.805 NA
20 AYILAM Vamanapuram WFR south of Tapi Thiruvananthapuram 10.685 NA
21 ARANGALI Chalakudy WFR south of Tapi Trichur 7.61 NA
22 MUTHANKERA Kabini Cauvery Wyand 712.735 22-06-1992


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CWC’s hydrographs showing Rivers Kabini, Bharatpuzha & Valapatnam unprecedentedly crossing highest flood levels. 

In Conclusion Its clear that major storage dams of Kerala like Idukki and Idamalayar, by releasing water when Kerala is facing floods due to widespread heavy rainfall, are adding to the flood misery of Kerala. This could have been avoided if the dam operators had started releasing water in advance rather than waiting for dams to be filled up, when they have no alternative but to release water. Its also clear that there was sufficient time and relatively dry period when they could have released water, rather than when Kerala is facing floods. If the Idukki power unit that was taken out or operation from June 26, giving “Annual Maintenance” as reason was in stead taken for annual maintenance during drier summer months, that would have helped, particularly when one unit is already out for renovation. If the water level in Idukki was lower before the onset of monsoon, it would have helped. CWC’s absence in flood forecasting is also additional handicap.

All this requires action. Possibly one of the first things, post current phase of rescue and emergency, that Kerala govt can do is to institute an independent inquiry into these issues, so that such situations do not recur, when dams, in stead of helping moderate the floods, add to the flood misery.

Himanshu Thakkar, SANDRP (ht.sandrp@gmail.com)


[i] https://www.thehindu.com/news/national/kerala/water-inflow-slows-down-in-idukki-dam/article24565074.ece, https://www.business-standard.com/article/pti-stories/idukki-dam-alert-continues-as-water-level-nearing-maximum-118073101490_1.html, https://english.manoramaonline.com/news/kerala/2018/07/31/idukki-dam-shutters-opened-reasons.html

[ii] https://npp.gov.in/public-reports/cea/daily/dgr/31-07-2018/dgr7-2018-07-31.pdf


14 thoughts on “Idukki Dam releases water when Kerala is in Floods: Could this have been avoided?

  1. Why would any one do a maintenance in summer when the power consumption is high? It always makes sense to do it in rainy season when the consumption is known to be low.


    1. Because there is least amount of water in rivers/ reservoirs in summer in Kerala and hence least power generation and hence possible to afford down time. In monsoon, with max flows, there is max power generation possible, when developers like to have all the machines available.


  2. Let’s not talk beyond the point – as why the hell did they let the water level to rise to freaking critical points, why didn’t they release at first signs of high levels and then they have weather forecasts reports!!

    We should demand explanation why wait??

    Negligence, total negligence I see here!

    Immorality if they thought of generating more power later despite warnings!!

    Listen India – wake up !!


  3. Himanshu. Great article and brilliant analysis. I came across you and your SANDRP when I saw a BBC article this mornign where you and SANDRP were mentioned. It is gratifying that I wasnt alone in wondering why the dams were opened in the peak floods (after all, flood control is a vital requirement of multipurpose dams) and I had written a post in a site called Bharat Rakshak (https://forums.bharat-rakshak.com/viewtopic.php?f=1&t=7660&start=200#p2289566) where I had called out the dam opening schedule and why there was no warning at all. From your post (and the BBC article quoting you),I learn that there is absoltuely NO warning issued at all to states like Kerala .Whatever happened to the IMD plan of putting in Doppler Weather Radars all over the country. Did the doppler radars in Trivandrum and Kochi not forecast the precipitation that was coming atleast a few hours (say 12 hrs) in advance ? What is the point of having forecasts if they are not widely disseminated in real time and there are agencies receiving it to act on them and systems are set up to act on this and make informed decisions.

    I do wish that you ,your organization and other organizations in this area take this forward and make sure that we have India fully covered with doppler weather radars with no gaps, we get micro forecasts with great granulartiy on all severe weather events (flooding, hail, snow, storm, tornadoes )and that we have a centralized agency /weather service (an expanded IMD?) and that this is not split into silos into different organizations and the inevitable turf wars , infighting and buck passing that would follow and that the state and local level adminstrations and disaster management teams have sufficient notice to plan for the impending disaster and that the information can be intelligently used to put in place measures to proactively manage it. No part of India should ever face a disaster like this unprepared and without sufficient warning .

    Please do not publish my email anywhere. I value my privacy and dont wish to receive an emails/ phone calls/ anything on what I write or blog anywhere . Than you for your understanding.


  4. Yes. It’s a man made disaster. And this isn’t the first one. Similar disaster occured in erstwhile unified AP in 2009, when allegedly due to late CM YSR’s insistence on filling up Srisailam reservoir to the brim so that water can be diverted to his district , the reservoir water denued release in downward course flowed down backwards inundating Kurnool district – washing away large part of Kurnool town and silting large area of agricultural lands along the course of river upto Nandyal town some 30 Kms away. MOST OF THE MISERIES OF INDIANS is due to Politicians as these JACKS of all Trades who aren’t accountable to any one take or delay decisions which make or break lives of millions of people. HIGH LEVEL ENQUIRY MUST BE ORDERED INTO KERALA MANMADE DISASTER AND THE GUILTY SHOULD BE PUNISHED. Of course the State to divert attention of people will play RELIEF POLITICS AND BLAME CENTRE


  5. Questions:

    1. Do other dam systems in India or abroad follow this ‘releasing during drier season’?
    2. Do you know what was the daily rainfall that the catchment area received and the inflow?
    3. If you were in control, at what level would you have released the water?


    1. 1. Yes
      2. Inflow not in public domain
      3. Firstly follow the rule curve. Secondly release more water when you have advance information about rainfall and there is forecast of heavy rains.


  6. A very good article. Is it not mandatory to have a Dam manual when the Dam is Commissioned? And that manual has to have details of when to release how much water etc? And that should be based on the current storage level, the present inflow, and the forecast of rain in the catchment area for the next one week. If such a manual is not available, is it not time to prepare one? Also no one, including the Ministers should be allowed to over ride the same.


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