Key reservoirs in the country, except those in the south, are showing comfortable storage levels for this time of the year, as they wait for a fresh infusion of waters from monsoon rainfall in a few days’ time. The 91 big reservoirs currently hold a total of 35.053 billion cubic metres of water that is about 10 per cent more than what is expected at this time of the year, according to latest data released by the Central Water Commission that manages these reservoirs. This is also 27 per cent more than the storage of last year at this point of time.
With the forecast of a normal monsoon this season, the reservoirs could be expected to fill up to healthy levels in the coming weeks. Though the monsoon has not been officially declared to have arrived on the Kerala coast, many parts of southern India have already started receiving rainfall. This should help the major reservoirs in these areas, in the basins of Krishna, Cauvery and other east-flowing rivers, which are left with little water right now. The reservoirs in these basins are now deficient by 75 per cent in storage as compared to normal levels at this time of the year.
The water levels in the reservoirs are used not just for irrigation and hydropower generation but for drinking water supplies as well. The four-month monsoon season, which accounts for about 75 per cent of India’s annual rainfall, is crucial to replenishing these reservoirs, many of which reach their maximum storage capacities during this time. The 91 big reservoirs — 31 of them are in the five southern states — have a total capacity of about 158 billion cubic metres. This is more than 60 per cent of the total capacity in all the reservoirs in the country put together.
As of now, 80 of these 91 reservoirs have are filled only up to 40 per cent of their capacities, which is normal during the pre-monsoon season. Just two of them, Sardar Sarovar Gujarat and Gerusoppa in Karnataka are more than 70 per cent full. A total of 38 reservoirs are showing storage over their expected normal levels, while 47 of them have storage more than last year at this point in time.
The reservoirs in the Narmada, Mahi, Ganga, Sabarmati, Godavari, Tapi and Mahanadi basins are showing better than normal storage as of now while those in the Indus and west flowing rivers of the south have normal water levels.
Of the total 35.053 billion cubic metres storage, 4.36 bn cu m is being held in the six reservoirs of north India, 5.66 bn cu m in the 15 reservoirs of eastern region, 6.87 bn cu m in the 27 reservoirs of western India, 14.25 bn cu m in the 12 reservoirs of central India, and 3.92 bn cu m in the 31 reservoirs of southern India.
The India Meteorological Department has predicted a normal monsoon this season. During the June to September season this year, the country as a whole is expected to receive rainfall that is 96 per cent of the average annual rainfall between the period 1961 and 2011.
Monsoon is expected to hit the Kerala coast, signalling its arrival on Indian mainland, on Tuesday, two days ahead of the scheduled date of June 1. “Present meteorological conditions indicate that conditions are favourable for onset of southwest monsoon over Kerala on 30th May. Simultaneously, onset is likely over most parts of northeastern states as well,” the IMD said in its latest bulletin on Monday.