Assam · brahmaputra · Dam Induced Flood Disaster · Floods

Role of Doyang Dam in bringing unprecedented floods in Golaghat

When Dhansiri river broke the highest flood level mark at Numaligarh site in early hours of Aug 2, 2018 in Golaghat district in Assam, it was not only completely out of the blue, the whole episode was unprecedented.

The earlier Highest Flood Level of Dhansiri River at Numaligarh was 79.87 m. The new HFL, it seems, was 80.18 m, full 31 cm above the previous HFL. This is rather rare, normally the new HFL would be a few cm higher, not almost one third of a meter. Secondly, the water level remained above 79.87 cm, the old HFL, for over 60 hours. This is also unusual, normally the water level rarely remains above HFL for more than a day or so. Thirdly, the earlier HFL was achieved on Sept 24, 1985, so this sudden episode of flood was breaking 33 year old record.

Numaligarh 020818 0600

But more surprising was that when we go through the IMD’s daily district level rainfall, we find that there has not been unprecedented rainfall in the Dhansiri River Catchment in the week preceding Aug 2, 2018, though there was some rainfall, the catchment has in fact seen deficit rainfall this monsoon. Similarly, there were no signs of such unprecedented rainfall or flood levels in other rivers around Dhansiri.

So what brought the unprecedented floods in Dhansiri River? The Assam Chief Minister, and groups like AASU and KMSS provide a clue when they allege that the Doyang Hydropower Dam upstream in Wokha district in Nagaland played a role. Did it?

Particularly when NEEPCO, the central govt company that owns and operates the dam claimed, on the contrary that Doyang dam helped moderate the flood peak in downstream river. But every dam operator makes such claims. Theoretically, every dam can help moderate flood in the downstream river, provided it is operated to achieve that objective. Most dams do not.

Numaligarh 070818

What are the facts about Doyang? Doyang dam has gross storage capacity of 535 Million Cubic Meters (MCM) and live storage capacity of 370 or 400 MCM as per different sources, NEEPCO website does not provide even these figures.This is substantial storage. The spillway of the dam has a capacity to release 5977 cumecs of water. This is massive, massive quantity for Doyang-Dhansiri rivers. So the dam certainly has the capacity to bring massive flood disaster in the downstream area if it is not operated properly.

So how was the dam operated? Shockingly, NEEPCO’s website provide no information about how the dam was operated in days preceding the Aug 2-4 Golaghat floods. NEECO website also does not provide any information as to how the dam is supposed to operate, particularly during monsoon.

Doyang Dam NE Now 310718
Doyang Dam NE Now on 310718

We find a clue about this from a CERC (Central Electricity Regulatory Authority, a statutory body) order, which provides the month wise design power generation figures for the Doyang Project. It says the Doyang project is supposed to generate 14.28 Million Units (MU) of electricity in whole of July.

How much electricity did Doyang produce in July 2018? According to National Power Portal of Central Electricity Authority of Government of India, Doyang Project produced 45.52 MU in July 2018!!! That is more than three times the electricity it is supposed to produce in July. This also tells us that by design, NEEPCO is supposed to keep water level low during July 2018,  so that there is minimum risk of floods to the downstream areas, but NEEPCO was completely violating that norm on daily basis. NEEPCO could not have produced three times the design energy without keeping the water level high in the dam, which is also completely against the basic principle of flood management.

WRIS map 0818
WRIS map showing location of Doyang Dam in Dhansiri Basin

And then when there was some heavy rainfall in the catchment area of Doyang project, NEEPCO claimed helplessness, saying we had no option but to open the gates to release the water. In press statement NEEPCO claimed that it had to open the dam gates on July 27, when downstream river was also flooded, creating unprecedented flood disaster in Golaghat.

But even July 27 onwards, NEEPCO continued to generate maximum electricity. So Doyang project generated, as per NPP website, 1.70 MU on July 31, 1.71 MU each on July 28-30, 1.76 MU on July 27, 1.78 MU on July 26, 1.67 MU each on July 20-24-25. This clearly means that the water level in Doyang dam even on July 24-31, was very high for NEEPCO to be able to generate so much electricity throughout this period. NEEPCO has clearly, completely violated the basic safety norms and design norms in order to generate maximum power in July 2018.

WRIS map Doyang Project
WRIS map showing location of Doyang Dam in Dhansiri basin

In Conclusion Some of the recommendations that flow from above analysis:

  • NEEPCO must accept that Doyang dam did have a significant role in increasing the flood disaster in Dhansiri river, Golaghat district during Aug 2-4, 2018. NEECO should compensate all those who have suffered due to the floods.
  • NEEPCO needs to assure everyone that it will adhere to the design norms and not increase the water level in dam to generate more power when it is not supposed to.
  • NEECO must put on its website, on daily basis, what is the Doyang water level, how much was inflows and how much was the water out flow and power generation. It can be on the lines of what Narmada Control Authority does[i], see:
  • NEEPCO should also put up on its website the Dam Operation Manual, including the rule curve that would state how the dam is supposed to be operated in filling period.
  • CWC needs to include Doyang reservoir in its inflow forecasting in its Flood Forecasting system.
  • CWC, IMD and NEEPCO needs to provide the daily rainfall in catchment of Doyang Dam on daily basis. For this they will need to put up rainfall measuring and transmission system. Today, even IMD’s daily district wise rainfall bulletin has blank spaces for every single day during July 25-Aug 6 for Doyang-Dhansiri catchment districts like Phek, Peren and Zunheboto districts in Nagaland.


Doyang Project Aug2018 3
Doyang Reservoir Photo from


More details about the Dhasiri Floods in Aug 2018 and role of Doyang Dam:

One of the earlier reports[ii] said on July 31, 2018 about the floods in Golaghat district: “A total of 36 villages of Golaghat district have been reeling under flood waters due to discharge of water from the dam of the Doyang Hydroelectric Project (DHEP) located in Wokha district of Nagaland. This has triggered panic among the affected villagers in the district. The DHEP authority opened its sluice gates on Friday (July 27) to discharge excess water of the Doyang reservoir which keeps on increasing due to the incessant rains that have been continuing for the last couple of days in Wokha.”

The report quoted Rony Rajkumar, Project officer of District Disaster Management Authority of Golaghat district: ““The DHEP authority has informed us that once the water level in the Doyang reservoir comes below 324 meter, they will close the gates. They have also refuted all the rumours about the vulnerability of the dam due to the flood.” This thus officially confirmed that Doyang reservoir did have a role to play.

Reconfirming Doyang Dam’s role, the same report quoted Nina Barua, district information and public relations officer of Golaghat district saying: “As informed by the North Eastern Electric Power Corporation Limited (NEEPCO) authority due to continuous rains in the catchment area, the water level of Doyang reservoir has been on the rise. In the meantime, all the gates are open for release of excess water from the dam”.

Doyang Project Aug2018 5
Doyang Dam and reservoir photo from

This was also confirmed by NEEPCO statement published in the Shillong Times: “The reservoir water level started increasing abruptly since July 25, 2018 with incessant rainfall in the upper catchment area. The inflow to the reservoir increased from over 600 cum/sec to over 1150 cum/sec on July 31, 2018, which is much higher than the normal range of inflow and necessitated release of excess water in a controlled manner by opening the radial gates at 5:30 am of July 27, 2018,” the NEEPCO statement said.

The gates were closed at 5 am on Aug 5, 2018, once the water level in Doyang reservoir went below 324 m.[iii] According to DDMA authorities, the stagnant flood  waters will take about a week to recede completely even if there is no more rain.

According to Daily power generation reports[iv] on National Power Portal, the Doyang project generated 1.73 MU on July 29, 2018 (1.70 MU on July 31, 1.71 MU each on July 28-30, 1.76 MU on July 27, 1.78 MU on July 26, 1.67 MU each on July 20-24-25, 1.43 on July 23, 1.54 on July 22, 1.46 each on July 9-10-21, 1.66 each on July 16-19, 1.68 on July 18, 1.65 on July 16, 1.24 on July 15, 1.57 on July 14, 1.53 on July 13, 1.47 on July 12, 1.52 on July 11, 1.41 on July 8, 1.36 each on July 1-2-6-7, 1.14 on July 5, 0.91 on July 4, 1.26 on July 3), against normal program generation of 1.35 MU. The project generated 25.08 MU during April-May 2018 and 26.99 MU during June 2018. During July 1-31, the project has generated 45.52 MU power.

Doyang Project Aug2018 6
Doyang dam and transmission lines

Some salient features of the Doyang Project as per National Register of Large Dams[v]:

  • Dam has live storage capacity of 216.5 MCM at EL 324.0 M and intercepts a catchment area of 2606[vi]

In the past too downstream affected people in the ten villages of Mengshanpen, Tsopo, Chudi, Longtsung, Sheruechuk, Morakjo, Lotsu, Pyangsa, Moilan and Pyotchu have said that the Doyang project led to very serious impacts in the downstream areas[vii]. The ten affected villages, under the banner of the Downstream Affected People’s Organization (DAPO), had in Aug 2015 submitted a representation to the Chairman and Managing Director of the North Eastern Electric Power Corporation Limited (NEEPCO), their grievances include:

  • Death of at least five persons between 2003 and 2014 due to the sudden “release of huge volumes of water”.
  • Very large number of people have suffered loss of livelihood. Movement of people across the river has been severely hampered.
  • Destruction of access to river, fisheries, water sources, hanging bridges, sand and boulder sources and river bed cultivation.
Doyang Project Aug2018 7
Doyang Dam photo from



[ii], this was largely repeated the next day in TELEGAPH: There were more reports:,






16 thoughts on “Role of Doyang Dam in bringing unprecedented floods in Golaghat

  1. Dear Sirs:

    The hydro power station (hps) at Doyang Dam produced 3 times the amount of electricity in July. This was done by letting out additional water from the dam to the turbines of hps, which created extra capacity in the reservoir of the Dam so as to accommodate any floodwater in August.

    How do you justify your statement “NEEPCO could not have produced three times the design energy without keeping the water level high in the dam,” “ This goes against the principles of hydropower generation. Extra electrical energy is produced NOT by keeping the hydraulic head high BUT by letting out more water to run the turbines which eventually lowers the hydraulic head thereby lowering the water level in the dam. This creates a capacity in the reservoir to absorb floods, which is the purpose of constructing the dam. Your comment is attached below.

    Please clarify.


    Dr Shrikant Limaye


    Doyang Project produced 45.52 MU in July 2018!!! That is more than three times the electricity it is supposed to produce in July. This also tells us that by design, NEEPCO is supposed to keep water level low during July 2018, so that there is minimum risk of floods to the downstream areas, but NEEPCO was completely violating that norm on daily basis. NEEPCO could not have produced three times the design energy without keeping the water level high in the dam, which is also completely against the basic principle of flood management.


    1. Basics: The hydropower capacity is decided by head and flow. The capacity once decided, based on limits on flow and head, there is no room for increasing the flow indefinitely. So high % of capacity generation necessarily means maximum possible flow for the project (fixed upper limit) and full head.


  2. Dear Sirs,

    As per CEA’s generation report, the program for generation from Doyang HPS in July 2018 was 42 MU. The actual production was higher at 46.91 MU (or 45.52 MU as per your report). However, in the same month of July last year (2017), the generation was 49.90 MU. So in fact the generation was less this year. Can you please give the reference to your statement as to what actually Doyang was supposed to generate in the month of July?

    Yours sincerely,
    Dweependra Nath Kalita


    1. As per design electricity generation norms decided by CEA while sanctioning the project, Doyang is supposed to generate around 14.4 MU in July. This should be the deciding factor. CEA’s program is clearly wrong to propose that Doyang will generate 42 MU in July as you say. Yes, Doyang has been violating the norms for several years, it should be held accountable for that.


      1. So, 14.4 MU is the design generation for July approved by CEA while sanctioning the project. If it is design generation, then it cannot be the deciding factor. Because design generation is based on 90% dependable year, and each year monthly generation will obviously be different, depending on the flows. NEEPCO’s website states that the annual design energy for the project is 227 MU. So, you may please provide/check the design energies of other monsoon months like June, August, September etc. They are likely to be much more than 14.4 MU, because otherwise how can the monthly design generations add up to 227 MU? In any case, monthly design energies are not limiting figures. Clearly, there is no question of violation by NEEPCO, at least on this count.


      2. No. For each month there is different design energy figures are given, totally for the year to 227 MU. So NEEPCO should not have violated this design energy for July, which also necessitated them to keep the water level much lower than the FRL. There is absolute and clear violation of Norms by NEEPCO by this count as on various other counts.


  3. Violation of design energy? If I was not fully clear in my earlier comment, please let me reiterate that monthly design energy is not a NORM.
    Will be grateful if you can provide the monthly design energies. Thank you.


  4. The author claimed that there were no unprecedented rainfall in the areas adjoining the river Dhansari. Well, the Dhansari flooded even before it converge with Doyang. Dimapur city itself was flooded even if it received less rainfall comparing to other districts of Nagaland. That’s because Nagaland state received an excess rainfall of over 72 percent from the period January to July 2018. And half of these rainfall directly goes to Dhansari river. So it is not rational to assume a high rainfall in adjoining areas of Dhansari for it to be flooded.


  5. Dear Sir,
    I have carefully gone through the above article and the comments and your replies. As all your earlier articles are aimed to blame hydro power projects, this is no different. Your claims to blame the Doyang hydro project are not based on hydro power Science. Hydro power projects are planned based on the hydrology of the river at project sites. Installed power and annual generation are calculated on basis of the water availability. If in a particular period, water availability is more, the power generation is also increased. In the non monsoon period, we frequently faced shortage of power from hydro projects because of scarcity of flow to the reservoir.
    Reservoir operations have significant role in flood moderation in the downstream and it is seldom noticed by anybody. As claimed by NEEPCO, it controlled flood for last 17 years and due to unprecedented rainfall in the catchment area, this year flood was beyond the capacity of the Doyand project reservoir to control . This claim of NEEPCO can be confirmed only after investigations by experts in the field.
    You have blamed Doyang project for generation of more electricity during the flood period. At the same time you have blamed Idukki dam for not producing power thus contributing to the Kerala flood . (Refer your article on kerala Flood dated 10.08.18). This indicates that you are highly biased against hydro power projects.


    1. Thanks, Sir,

      I with you could go beyond the ideological bias you come with. If you would have seen the issues on merits, you would have understood how Idukki created disaster by not able to generate optimum power and Doyang created disaster by doing the opposite. There is no contradiction there. Contradiction is seen because of ideological glasses you are wearing.


  6. Mr. Humptsoe’s observation prompted me to look into the rainfall aspect. TRMM data of NASA shows that the Dhansiri basin received about 545mm during the month of July 2018. This is the highest rainfall since 2000. The average July rainfall from 2000 to 2017 stands at 366mm. If we talk of specific dates i.e. in the week preceding Aug 2, 2018 as referred in your article, the Dhansiri basin received 179mm against the average of 90mm received during that specific week from 2000 to 2017 – almost double! This vindicates Mr. Humptsoe’s point, also Mr. Mohammed’s mentioning of unprecedented rainfall in the catchment.


    1. Plz share all the links where I can cross check these figures. It still does not help NEEPCO or Doyang to go scot free, but for my education, would like to see how/ from where you got all these figures.


      1. The author should have cross check the data beforehand. The unsubstantiated data and statements have negated even the real and humane issue highlighted in the article.


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