The India Climate Observatory

Commentary, action and research on climate and development in India

Big water storage wheel

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The Central Water Commission, Ministry of Water Resources, Government of India, monitors every day the quantity of water stored (and used from) each of the 91 major reservoirs of the country. It issues a bulletin every week that gives the weekly storage position of these reservoirs – the volume of water, the level of water in the reservoir and the change from the last week, the change from the same date last year and from the average on this date of the last ten years.

The water storage capacity of these 91 reservoirs taken together is 157.799 billion cubic metres (bcm) which is estimated to be about 62% of the total water storage capacity (in other smaller dams and storage structures all over the country) that has been built and is being used, and which is approximately 253.38 bcm. Out of these 91 reservoirs, hydro-electric power stations (with a capacity of 60 megawatts and more) are attached to 37 reservoirs.

In this illustration by Indiaclimate, for the first time the total storage capacity of the 91 major reservoirs has been visually mapped to show reservoir, state and zone capacities relative to each other and the total.

These are the reservoirs with state, reservoir name and full reservoir level in billion cubic metres (bcm). For a good quality file that you can print, write to us.

South zone reservoirs (AP for Andhra Pradesh, TG for Telengana, APTG for Andhra Pradesh and Telegana together, KAR for Karnataka, TN for Tamil Nadu, KER for Kerala): AP, Somasila (1.994); TG, Sriramsagar (2.3); TG, Lower Manair (0.621); APTG, Srisailam (8.288); APTG, Nagarjuna Sagar (6.841); KAR, Krishnaraja Sagra  (1.163); KAR, Tungabhadra (3.276); KAR, Ghataprabha (1.391); KAR, Bhadra (1.785); KAR, Linganamakki (4.294); KAR, Narayanpur (0.863); KAR, Malaprabha (Renuka) (0.972); KAR, Kabini (0.444); KAR, Hemavathy (0.927); KAR, Harangi (0.22); KAR, Supa (4.12); KAR, Vanivilas Sagar (0.802); KAR, Almatti (3.105); KAR, Gerusoppa (0.13); KER, Kallada (Parappar) (0.507); KER, Idamalayar (1.018); KER, Idukki (1.46); KER, Kakki (0.447); KER, Periyar (0.173); KER, Malapmuzha (0.224); TN, Lower Bhawani (0.792); TN, Mettur (Stanley) (2.647); TN, Vaigai (0.172); TN, Parambikulam (0.38); TN, Aliyar (0.095); TN, Sholayar (0.143). Total for 31 reservoirs 51.59 bcm

West zone reservoirs (GUJ for Gujarat, MAH for Maharashtra): GUJ, Ukai (6.615); GUJ, Sabarmati (Dharoi) (0.735); GUJ, Kadana (1.472); GUJ, Shetrunji (0.3); GUJ, Bhadar (0.188); GUJ, Damanaganga (0.502); GUJ, Dantiwada (0.399); GUJ, Panam (0.697); GUJ, Sardar Sarovar (1.566); GUJ, Karjan (0.523); MAH, Jayakwadi (Paithon) (2.171); MAH, Koyana (2.652); MAH, Bhima (Ujjani) (1.517); MAH, Isapur (0.965); MAH, Mula (0.609); MAH, Yeldari (0.809); MAH, Girna (0.524); MAH, Khadakvasla (0.056); MAH, Upper Vaitarna (0.331); MAH, Upper Tapi (0.255); MAH, Pench (Totaladoh) (1.091); MAH, Upper Wardha (0.564); MAH, Bhatsa (0.942); MAH, Dhom (0.331); MAH, Dudhganga (0.664); MAH, Manikdoh (Kukadi) (0.288); MAH, Bhandardara (0.304). Total for 27 reservoirs 27.07 bcm

East zone reservoirs (JHR for Jharkhand, ODI for Odisha, WB for West Bengal, TRI for Tripura): JHR, Tenughat (0.821); JHR, Maithon (0.471); JHR, Panchet Hill (0.184); JHR, Konar (0.176); JHR, Tilaiya (0.142); ODI, Hirakud (5.378); ODI, Balimela (2.676); ODI, Salanadi (0.558); ODI, Rengali (3.432); ODI, Machkund (Jalput) (0.893); ODI, Upper Kolab (0.935); ODI, Upper Indravati (1.456); WB, Mayurakshi (0.48); WB, Kangsabati (0.914); TRI, Gumti (0.312). Total for 15 reservoirs 18.83 bcm

Central zone reservoirs (UP for Uttar Pradesh, UTT for Uttarakhand, MP for Madhya Pradesh, CHT for Chhattisgarh): UP, Matatila (0.707); UP, Rihand (5.649); UTT, Ramganga (2.196); UTT, Tehri (2.615); MP, Gandhi Sagar (6.827); MP, Tawa (1.944); MP, Bargi (3.18); MP, Bansagar (5.166); MP, Indira Sagar (9.745); MP, Barna (0.456); CHT, Minimata Bangoi (3.046); CHT, Mahanadi (0.767). Total for 12 reservoirs 42.30 bcm

North zone reservoirs (HP for Himachal Pradesh, PUN for Punjab, RAJ for Rajasthan): HP, Gobind Sagar (Bhakra) (6.229); HP, Pong Dam (6.157); PUN, Thein  (2.344); RAJ, Mahi Bajaj Sagar (1.711); RAJ, Jhakam (0.132); RAJ, Rana Pratap Sagar (1.436). Total for 6 reservoirs 18.01 bcm

Decoding reservoirs for the rest of us

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RG_ICP_reservoirs_201407_imageEvery week, the Central Water Commission releases to the public and to government departments the numbers that describe how much water is stored in 85 reservoirs in India. These are the reservoirs designated as nationally important, because of their roles in providing water for large irrigated command areas and for generating hydro-electric power (37 of these dams).

These readings are taken as the authoritative compilation of the current weekly state of water storage, and are widely used in government. Amongst the uses is to recommend the rationing of water consumption in the states and urban settlements. Another use is to help determine what advice to broadcast to our farmers about when they can sow seeds (if their fields are irrigated by the canals that radiate outwards from these dams).

RG_ICP_reservoirs_panel_201407But of course these are only 85, even if they are the biggest. Whether Bargi in Madhya Pradesh is half full does not interest in the least a farmer in Purnea, Bihar. Whether Tungabhadra in Karnataka is filling up well in the last two weeks is of no consequence to the residents of Rohtak in Haryana. That Yeldari in Maharashtra has water at a level very much lower it should be at this time of the year does not affect the cultivators of Virudhanagar, Tamil Nadu.

Bihar has 24 large dams (and groundwater) and Tamil Nadu has 116 while Madhya Pradesh has 898 large dams other than Bargi, but we have no weekly or monthly information about how much water these hold, in the first week of June or at end July. And this is what we don’t know for all the 4,839 dams – in the national register of large dams – that are not amongst the list of 85. The Central Water Commission tells us that it uses the combined readings for the 85 large dams because, with their total of about 155 billion cubic metres (bcm) of water storage (if they are all full), they form a large portion of the approximately 254 (bcm) of total reservoir storage available in India (excluding tanks, ponds and traditional water storage structures). But, for the smallholder cultivator and the town council of a Class 2 urban settlement, it is the 50 million cubic metres reservoir in the next taluka that they depend on for water, not on any of the big 85.

What can we then do with the weekly reservoir storage bulletin from the CWC? My approach is to treat it as an indicator of the collection of rainfall by reservoirs in the same meteorological region and agro-ecological zone. When the list is divided into ten groups, by reservoir size, we see far more clearly the effect of the last two weeks of rainfall on the storage levels. Until we can persuade state and central governments to invest in widespread and cheap monitoring of as many of our water storage receptacles as possible, we may use the CWC bulletin as an indicator.

By Rahul Goswami

The panel of charts shows water storage ranges (at full capacity of the dams) for the groups of reservoirs. Starting with the smallest first: 56 million cubic metres (mcm) to 176 mcm (tenth group); 184 mcm to 380 mcm (ninth group); 399 mcm to 523 mcm (eighth group); 524 mcm to 735 mcm (seventh group); 767 mcm to 927 mcm (sixth group); 935 mcm to 1.436 billion cubic metres (bcm) (fifth group); 1.456 bcm to 1.994 bcm (fourth group); 2.171 bcm to 2.676 bcm (third group); 3.046 bcm to 5.378 bcm (second group); 5.649 bcm to 9.745 bcm (first group).