Disasters · Floods

CWC’s Weekly Reservoir Bulletin: Closer look warns of impending disaster

One of the key source of information about India’s water availability that the government provides and media and everyone else quotes is Central Water Commission’s weekly (updated every Thursday) “Reservoir Storage Bulletin”[i]. The Reservoir Storage Bulletin (RSB) currently tells about water storage position of 91 storage dams across India with total live storage capacity of 161.993 BCM (Billion Cubic Meters), spread over 18 states and 12 river basins. CWC uploads it with a disclaimer: “The Data contained in this Bulletin is as received from the State Government/Project Authorities.”

While this is a useful source of information, since it is the only information source on water situation that is available from government on timely basis every week, it needs to be scrutinized closely.

Why so much water in these dams close to onset of monsoon? For example, as India awaits the onset of monsoon from early June, a scrutiny of the CWC’s RSB dated May 31, 2018 should not be looked at just from the point of water scarcity in the reservoirs by comparing with the storages in same week in previous year or average of last 10 years as most media has done. The scrutiny at this stage (as also earlier stages) should also look at how much water is there in various reservoirs as the monsoon inflows would start into these reservoirs within weeks.

Why is this important? It may be recalled as to what is the basic logic of creating reservoirs. The basic logic is that while most of the rain, the primary source of our water, is available in 3-4 monsoon months (June-Sept), but we need to store that water to make it available for the rest of the 8-9 non monsoon months. The reservoirs are created at huge social, economic and environmental costs for this basic purpose. So the optimum use of the reservoir would be when we have been able to use up most of the water stored in these reservoirs in 2017 monsoon, before the onset of 2018 monsoon.

Reservoir managers and government officials, however, have to be also prepared for the contingency of rainfall deficit in early monsoon, so that the water stored in reservoirs can be used during such a contingency. However, for this purpose, not more than 5-10% of live storage capacity is required. Particularly when almost none of India’s reservoirs are designed to carry over water beyond next monsoon.

What this means that is that if the any dam has water storage of more than 5-10% of its live storage capacity, than, we are not using the reservoir optimally. If the water was supposed to be used before the next monsoon, why was it not used? This signifies first level of sub optimal use of the reservoir.

When we check CWC’s weekly RSB of May 31, 2018, we find that there are at least seven reservoirs that has over 1000 Million Cubic Meters (MCM) of water in live storage and there are eleven more reservoirs that had between 500-1000 Million Cubic Meters (MCM) of water in live storage. The list is given in the table below.

Reservoirs with over 1000 MCM water in Live Storage as per RSB of 310518 Reservoirs with 500-1000 MCM water in live storage as per RSB of 310518
Reservoir Name Live Storage, MCM Reservoir Name Live Storage, MCM
Minimata Bango 1556 Srisailam 720
Supa 1365 Rihand 643
Hirakud 1307 Koyna 701
Gandhi Sagar 1154 Jayakwadi 581
Bargi 1416 Pong 562
Bansagar 2224 Thein 583
Indira Sagar 1156 Mahi Bajaj Sagar 542
Ukai 769
Kadana 612
Linkanmakki 605
Rengali 769
Total 10228 Total 7087
GRAND Total 17315

The total water stored in live storage of the 91 reservoir on May 31, 2018 was 27659 MCM, which means that about two thirds of that quantity was stored in just 18 reservoirs.

IS THERE ANY JUSTIFICATION FOR SUCH HIGH STORAGE IN THESE 18 RESERVOIRS JUST BEFORE MONSOON? Let us look at some of these reservoirs and their river basin situation.

  • BANSAGAR: This reservoir on Sone river (Ganga Basin) in Madhya Pradesh is an interstate project between Uttar Pradesh, Madhya Pradesh and Bihar. In Aug 2016, when monsoon was less than hallway through, massive water releases from this dam contributed hugely in creating unprecedented flood disaster in Ganga basin in Bihar[ii]. The Bansagar reservoir on the morning of Aug 19, 2016 started releasing close to 16000 cumecs (cubic meters per second) water, which led to the floods in Ganga two days later. On June 25, 2016, when Bansagar Reservoir filling started, the reservoir already had about 1809 MCM water. This year, with even higher storage, Bansagar could again create another massive floods in the downstream areas including in Bihar.
Official Sone Basin Map from Bansagar Control Board
Map Showing the location of Bansagar Dam, Sone River, Ganga River and Patna
  • GANDHISAGAR: This massive reservoir on Chambal River is also in Ganga Basin and there is Chambal Ghadiyal Sanctuary downstream from this dam. The government keeps saying it has no water for the Sanctuary, but as we see, the reservoir had 1154 MCM water in live storage, which could have been used for a number of purposes including for sustaining the Chambal River through the Ghadiyal Sanctuary.
  • GANGA BASIN: There are at least three dams in the table above (Bansagar, Gandhi Sagar and Rihand) that are in Ganga Basin. Even though the Prime Minister has pledged to rejuvenate Ganga, the government has been unable to allocate any water for rejuvenation of Ganga. The situation of Ganga this summer of 2018 is so precarious that at many locations people are crossing the river by walking across. Now we have these three Ganga Basin reservoirs with over 4000 MCM water, but that water wont be used for Ganga?
  • NARMADA BASIN: Throughout this year Narmada river in Gujarat has been in news for water scarcity, salinity ingress, drying river with no water even for last rites at Chandod. Now we see in the above table that two reservoirs (Indira Sagar and Bargi) have over 2570 MCM water, which could have been used for Gujarat’s needs for Narmada River, as Gujarat government had even pleaded. Now most of this water will not be used before the monsoon, but the water was not released for Narmada river in Gujarat.
  • MAHANADI Basin: Chhattisgarh and Odisha are at logger heads over use of Mahanadi water. Here we find that there is 1307 MCM water in Hirakud dam on this river in Odisha ad here is 1556 MCM water on Minimata Bango Dam in this river basin in upstream Chhattisgarh. Its shocking to note that the Minimata Bango Dam have been having such high water storage every year even on the eve of the monsoon.

Clearly, so much water in live storage in all these dams just days before the monsoon raises serious questions.

FURTHER SUB OPTIMALITY and RISK OF FLOOD DISASTER It should be noted here that water already stored in live storage in these dams means that this space will not be available for storage of monsoon inflow during monsoon 2018. This signifies further sub optimality in use of these reservoirs. Moreover, as we saw in case of Bansagar Dam creating flood disaster in Bihar in Aug 2016, all these reservoirs could also be source of additional flood disasters during 2018 monsoon, thus creating additional risk.

To illustrate, TENUGHAT Dam in Jharkhand over Damodar river in fact took advance action by releasing excess water on June 4, 2018, before the onset of monsoon after informing the downstream state[iii]. The reservoir had 318 MCM water in live storage on May 31, 2018, equal to 39% of live storage capacity. The live storage was reduced to 303 MCM on June 6, 2018. It may have been useful if the reservoir had taken more advance action and put the water to more optimum useful purpose.

More Questions about CWC’s Reservoir Bulletin The media and civil society groups can scrutinise the CWC’s Reservoir Bulletin keeping in mind more questions, some of which are listed here.

  • The bulletin provides a very small part of water reality of India. Firstly, it should be noted that since most of the water that India consumers for key water uses like irrigation, rural, urban and industrial water supply comes from groundwater, the bulletin does not provide key water reality.
  • Even in terms of surface water storage, the bulletin only provides information for LARGE surface storages. There is MASSIVE water storage capacity available in India through smaller storages, about which CWC has no clue either in terms of storage capacity or water stored at any given point of time.
  • Even among larger reservoirs, out of India’s 5254 large dams as per CWC’s National Register of Large Dams[iv], the RSB provides information only for 91 reservoirs. As per CWC’s 2017 Integrated Hydrological Data Book, the total storage capacity that India has is about 254 BCM, as against that, the RSB covers storage capacity of 161.99 BCM.
  • However, there is more detailed information available on websites of a number of state governments, much of which is updated on daily basis rather than weekly that CWC gives. For example, Maharashtra Reservoir Live storage[v]: This daily bulletin provides storage situation for Maharashtra’s 140 Major, 257 Medium and 2849 minor projects with live storage capacities of 29.13 BCM, 5.40 BCM and 6.34 BCM, grand total of 40.87 BCM for 3246 reservoirs collectively. Out of these, for 103 major reservoirs, the information is available individually, for the rest, it is available region wise and collectively. CWC’s RSB has information about 17 Maharashtra reservoirs with total live storage capacity of 14.073 BCM.
  • Similarly, for Madhya Pradesh[vi]: Daily Reservoir Bulletin provides information about 164 reservoirs with cumulative live storage capacity of 36.415 BCM. CWC’s RSB has information about 6 MP reservoirs with total live storage capacity of 27.318 BCM.
  • A number of other states (e.g. Gujarat, Tamil Nadu, Karnataka, Odisha) provide some information about reservoir storage, but this is not as detailed and consistent as that of Maharashtra and Madhya Pradesh.
  • Strangely, the bulletin does not provide names of the river basin for the 91 dams listed by it. This information is necessary to cross check the basin level situation that the bulltin provides.

In Conclusion It is clear that the dam reservoirs created in India at huge expenses are being operated sub optimally on several counts. CWC’s weekly Reservoir Storage Bulletins, while providing some useful information, is very limited in terms of giving true picture of the water scarcity or storages. CWC can also easily provide information on daily basis and for more reservoirs. One hopes the media will continue to raise critical questions about the weekly reservoir storage bulletin of CWC so that this crucial information is available to all concerned.

Himanshu Thakkar (ht.sandrp@gmail.com)


[i] See:

[ii] https://sandrp.in/2016/08/23/a-tale-of-two-dams-is-bihars-unprecedented-flood-an-avoidable-man-made-disaster/

[iii] http://www.dailypioneer.com/state-editions/ranchi/tenughat-dam-releases-water-ahead-of-monsoon.html

[iv] http://cwc.gov.in/main/downloads/NRLD_04012017.pdf

[v] https://wrd.maharashtra.gov.in/portal/content/default/pdf/contents/home/damstorages.pdf

[vi] http://eims1.mpwrd.gov.in/fcmreport/control/generatefcmdailyreport;jsessionid=7806C517FAE57B2CE0FD16D16B60FE76.jvm1?sdate=09/06/2018&dhiStatus=N

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