Why water reserves in southern India are fast depleting in 2023

What are the currently available stocks in the dams?

The CWC monitors 42 reservoirs located in the southern states: Andhra Pradesh, Telangana, Karnataka, Kerala and Tamil Nadu. Their collective storage capacity is 53.334 Billion Cubic Metre (BCM).

There has been a sharp drop, observed over the past two months, in the already low water reserves. In September 2023, the water stocks stood at 25.609 BCM (48 per cent of the total storage capacity), which then dropped to 24.575 BCM (46 per cent of the total storage capacity).

According to the latest CWC report issued in the third week of November, this stock has dropped further to 23.617 BCM (44 per cent of the total capacity). Last year around this time, the collective water reserves were 87 per cent of the total storage capacity of these states.

Latest reservoir stocks. (Source: CWC)

During normal monsoon years over the country, the available water reserves in southern India touch 91 per cent of the total storage capacity. Even though the country as a whole recorded normal rainfall in 2023 (820mm, 94 per cent of the Long Period Average), the monsoon over the south peninsular was not appreciable.

(Source: CWC)

Why are the stocks low?

There was a vast inter-seasonal rainfall variability recorded during the southwest monsoon this year. Rainfall records by the India Meteorological Department (IMD) showed that the south peninsular India received normal or above rainfall only during the July 26-August 3 period during the four-month season.

The season, thus, ended with seeing large-scale rainfall deficits – June (-45 per cent), July (45 per cent), August (-60 per cent) and September (49 per cent), which cumulatively ended with 8 per cent below normal, which was quantitatively 659mm.

October over southern peninsular India remained the sixth driest in 123 years. The rainfall recorded was 58.7mm against a normal of 148.2mm. Normally during October, most of southern India receives rainfall, contributed by the retreating southwest monsoon and the incoming northeast monsoon.

However, cyclone Hamoon’s development in the Bay of Bengal during the onset phase of the northeast monsoon dampened the rainfall activity, particularly over Tamil Nadu and coastal Andhra Pradesh, the IMD officials had said.

As a result, the collective rainfall deficiency in south peninsular India slipped to 60 per cent. The recorded rainfall during October was Andhra Pradesh and Yanam (-90 per cent), Rayalaseema (-90 per cent), Tamil Nadu, Karaikal and Puducherry (-43 per cent), and Kerala (1 per cent).

Barring a handful, all other districts of Andhra Pradesh and Rayalaseema remained highly rain-deficient and nearly dry last month.

Most rain-deficient districts in southern peninsular India during October 2023. (Source: IMD)

What areas need urgent attention?

The shrinking of water reserves is not an encouraging development.

The immediate impact could be felt on irrigated farming, particularly the high water-intensive paddy cultivation which is largely undertaken in Andhra Pradesh and Tamil Nadu.

Besides, during the unfolding months, the impact will spiral over to the availability of drinking water.

While Karnataka has begun declaring drought-hit talukas, other states may soon follow suit. With new state governments to be sworn in in Andhra Pradesh and Telangana, it would be a challenge to tackle the agri-crisis triggered by water shortage.

Anjali Marar works at the Raman Research Institute, Bengaluru.