Monsoon watch. Water levels in half the reservoirs dip below 10-year average 

Water levels have been low in the reservoirs in our country, compared to how things were last year.  As of June 30, 2023, the live water storage available in India’s 146 reservoirs is 47.95 billion cubic metre (BCM). It was 49.02 BCM, in the corresponding period in 2022. “The live storage available in these reservoirs is 47.95 BCM, which is 27 per cent of the total live storage capacity of these reservoirs,” reads the CWC bulletin.

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Also, 81 reservoirs have water storage less than 2022 levels and in 73 of them, water levels are lower than the 10-year-average numbers, shows the Central Water Commission data. While things appear fine in the reservoirs located in the Northern, Eastern and Central regions of the country, it looks quite bad in the South and the West.

Commenting on the situation in the Southern region, which includes Kerala, Tamil Nadu, Andhra Pradesh, Telangana and Karnataka, the CWC bulletin notes, “The total live storage available in these reservoirs (in the southern region) is 10.375 BCM which is 20 per cent of total live storage capacity of these reservoirs. The storage during the corresponding period of last year was 35 per cent and the average storage of the last ten years during the corresponding period was 23 per cent of the live storage capacity of these reservoirs.”

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This could be owing to the low rainfall in June. Many regions in the country are yet to get a noseful of petrichor, for the rain gods weren’t kind enough in June. The latest data from the CWC and the Indian Meteorological Department suggest that in the entire month of June, more than 50 per cent of IMD’s subdivisions received 80 per cent lesser than normal rainfall in June.

That is 19 out of IMD’s 36 subdivisions. These regions include Bihar, Marathwada, Kerala, South Interior Karnataka and East Uttar Pradesh. In these regions, ‘per cent departure from normal’ of rainfall received was between -69 and -58. In rainfall predictions, “per cent departure from normal” refers to the deviation or difference between the expected rainfall amount and the long-term average or normal rainfall for a specific time period and location. 

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“The departure from normal is expressed as a per cent, indicating whether the expected or observed rainfall is above normal (positive departure) or below normal (negative departure). A positive departure means that the rainfall is expected to be higher than the long-term average, while a negative departure indicates that it is expected to be lower. The larger the departure percentage, the greater the deviation from the normal rainfall,” said Anjal Prakash, Associate Prof (research) at the Indian School of Business. He also adds that the reasons for this could include climate change, climate oscillations like El Nino and weather patterns.

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