Reservoir levels have seldom been this low in September, shows data

Nearly 40 per cent of storage capacity is unutilised

The amount of water in the country's reservoirs is lower than it has been for years.

The live storage in reservoirs has dipped to 111.74 billion cubic metres (BCM), as on 6 September 2023, as observed for 150 reservoirs. The lowest live storage in the corresponding comparable period was observed in 2017, when live storage was at 91.2 billion cubic metres, shows data since 2015 (the earliest year with immediately available numbers on the Central Water Commission website). The latest data is for 6 September. Similar data was collated from previous year bulletins. Since the bulletins are not released on the same date every year, the date closest to the current one was considered for previous years.

The trend also holds in terms of percentage of reservoir capacity utilised. The number of reservoirs monitored has varied over the years. For example, 91 reservoirs were monitored across the country in 2017. They were at 58 per cent of capacity. The current level is 62 per cent of the storage capacity (chart 1).
 

"...the live storage available in 150 reservoirs...is 74 per cent of the live storage of the corresponding period of last year and 86 per cent of storage of the average of the last ten years," said the latest bulletin.

August rainfall was 36 per cent below the long-term average this year, at 162.7 millimetres (mm).

"Rainfall over all India was lowest (162.7 mm) since 1901 against the previous record of 191.2 mm in 2005. Rainfall over the homogeneous region of Central India (165.0 mm) and the homogeneous region of South Peninsular India (76.4 mm) was also lowest since 1901 against 172.8 mm over Central India in 1905 and 89.4 mm over the South Peninsula in 1968. Rainfall over the homogeneous region of Northwest India (339.3 mm) was the 8th lowest since 1901," said the India Meteorological Department climate summary for August 2023.

A regional split shows some divergence in the availability of water relative to previous years.

The eastern region seems the worst affected by the rain shortfall of recent months. Reservoirs there have less than 10 billion cubic metres of water stored. This is the lowest for the beginning of September, as shown by bulletins going back to 2015. It is 16 billion cubic metres in the north, 26 billion cubic metres in the west, and 34 billion cubic metres in the central region; all in line with long-term averages. Southern reservoirs have 26 billion cubic metres worth of water, compared to 37 billion cubic metres seen on average over the preceding seven years (chart 2).