Water in reservoirs across India much below full capacity

Water in several reservoirs, mainly in the south of India, is significantly below the maximum capacity as a result of patchy rainfall due to a poor southwest monsoon in June. The only region which saw surplus rainfall was Northwest India.

Worryingly, as of June 27, the country has already registered a rainfall shortage of 32 per cent. Central India witnessed the largest deficit in June at 56 per cent, closely followed by South India with a 54 per cent shortage. East and Northeast India saw a 15 per cent deficit. The only region with surplus rainfall was Northwest India at 31 per cent as a result of pre-monsoon showers due to Western Disturbance.

The Indian Meteorological Department had predicted a normal monsoon, but Skymet had expected the upcoming monsoon to be 'below normal' to the tune of 94 per cent. Skymet had stated that besides El Nino, there were other factors too influencing monsoon. Indian Ocean Dipole (IOD) has the potential to steer monsoon and negate the ill effects of El Nino, when sufficiently strong.

The Indian Ocean Dipole (IOD) is defined by the difference in sea surface temperature between two areas (or poles, hence a dipole) — a western pole in the Arabian Sea (western Indian Ocean) and an eastern pole in the eastern Indian Ocean south of Indonesia, states Australia’s Bureau of Meteorology.

Depleting Reservoir Levels

As of 22 June 2023, the overall water storage position is less than the corresponding period of June 2022 in the country. The live storage in 146 reservoirs across the country is 46.23 BCM, which is 26 per cent of total live storage capacity of these reservoirs. However, last year the live storage available in these reservoirs for the corresponding period was 50.03 BCM. The total live storage capacity of 146 reservoirs is 178.19 BCM.

In the Southern region, which includes states of Andhra Pradesh, Telangana, Karnataka, Kerala and Tamil Nadu, the total live storage available in the 40 reservoirs is 10.990 BCM which is 20.71 per cent of total live storage capacity of these reservoirs. The storage during corresponding period of last year was 35% and average storage of last ten years, according to the Central Water Commission.

The crucial water source for Bengaluru, the Krishnarajasagar (KRS) Dam, which supplies Cauvery water for drinking purposes, is at 18 per cent storage as compared to normal levels. The water level is currently at a 77.6 feet, which is significantly below its maximum capacity of 124.8 feet.

Similarly, the Tungabhadra Dam in Karnataka, which caters to the Hyderabad and Karnataka regions, is at 19 per cent storage as compared to an average of the last 10 years storage. It currently holds storage of 4.1 TMC compared to last year’s 43.9 TMC of water.

In the Western region, the total live storage available in the 49 reservoirs is 8.507 BCM which is 23 per cent of total live storage capacity of the reservoirs. The storage during corresponding period of last year was 24 per cent. The Western region includes Gujarat and Maharashtra.

In Mumbai, the collective water storage in the seven reservoirs that supply drinking water to the city is now 6.49 per cent, according to the BMC data. Mumbai draws water from Tulsi, Tansa, Vihar, Bhatsa, Modak Sagar, Upper Vaitarna, and Middle Vaitarna.

The total live storage available in the 26 reservoirs in the Central region is 15.513 BCM which is 32 per cent of total live storage capacity of these reservoirs. The storage during corresponding period of last year was 29 per cent. Uttar Pradesh, Uttarakhand, Madhya Pradesh and Chhattisgarh are part of the Central region.

In the Eastern region, the total live storage available in the 21 reservoirs is 3.512 BCM which is 17 per cent of total live storage capacity of these reservoirs. The storage during corresponding period of last year was 16 per cent and average storage. The region includes Jharkhand, Odisha, West Bengal, Tripura, Nagaland and Bihar.

As per the reservoir storage bulletin published by the Central Water Commission, the total live storage available in the 10 reservoirs in the Northern region is 7.709 BCM which is 39 per cent of total live storage capacity of these reservoirs. The storage during corresponding period of last year was 26 per cent. This implies that the storage during current year is better than the corresponding period of last year. The region includes Himachal Pradesh, Punjab and Rajasthan.

Deficit rainfall

According to Mahesh Palawat of Skymet, Central India has seen a deficit of 24 per cent rainfall, East and Northeast regions 23 per cent, 27 per cent in the South and 46 per cent in the Northwest regions of the country. “There is likely to be 10-15 per cent deficit rain fall until the end of June. The onset of Monsoon was delayed, but it has progressed after June 25. There is a sudden improvement,” added Palawat.  

Kerala, Karnataka and Telangana have seen largely a deficit rainfall season at -65 per cent, -57 per cent and -53 per cent respectively. According to IMD, Maharashtra has seen a -63 per cent rainfall deficit season. Chhattisgarh, where rice is the main crop, has seen a -23 per cent deficit in rainfall. In Uttar Pradesh, the deficit rainfall is -29 per cent, while in Bihar it is -78 per cent as of 27 June 2023.