While heavy rainfall battered many parts of Delhi-NCR, Mumbai and other parts of India, disrupting daily life and causing waterlogging in several areas, Karnataka's capital Bengaluru has remain under a prolonged dry spell, which has raised a concern among the state government and local authorities.
According to a data, India's tech capital registered a 35 per cent deficit in rainfall between June 1 and July 9, while southern interior part of the southern state recorded a 24 per cent deficit during the same period.
Despite such a deficit, the Bangalore Water Supply and Sewerage Board (BWSSB) has maintained that there is no need to panic, and said that the city has sufficient water for three to four months; although it has accepted that several areas are facing water shortages due to a depletion in groundwater levels.
How Bengaluru gets its water?
Bengaluru overwhelmingly relies on the Cauvery River for its water supply, even though there are certain reservoirs in and around the city. Water is diverted at the Thorekadanahalli (TK Halli) intake and pumped through a network of pipelines and treatment plants under the Cauvery Water Supply Scheme. As the India's tech capital is around 900 metres above the mean sea level, the water is lifted nearly 500 to 600 metres in elevation, which is considered as one of the most energy-intensive urban water supply systems in the country.
Therefore, the availability of water in Bengaluru, which unlike other cities is not dependent on nearby reservoirs, largely depends on rainfall across the Cauvery basin.
What about the reservoirs near Bengaluru?
The city has two historic reservoirs: Hesaraghatta Lake and Thippagondanahalli (TG Halli) Reservoir. They are on the Arkavathi River, which was once the primary source of water for Bengaluru. But decades of declining inflows, rapid urbanisation, encroachment, pollution and groundwater depletion in the Arkavathi basin have led to a significant reduction in their yield.
Thus, the city has no other option but to depend on the Cauvery River to carter to its water needs.
There is one more reservoir in Bengaluru, though, which is the Manchanabele Reservoir. The Manchanabele Reservoir is on the Arkavathi River, which is roughly 40 kilometres from the city, but it is a supplementary source and water from this is mainly used for irrigation.
Why monsoon remains crucial for Bengaluru?
The southwest monsoon remains critical for Bengaluru, even though the city largely depends on the Cauvery River for its water supply. The rainfall helps in replenishing the Cauvery basin, feeding the Cauvery Water Supply Scheme and helps Bengaluru to meet its water needs. However, a weak rainfall would reduce water storage in the Cauvery basin's major reservoirs, particularly Krishnaraja Sagar (KRS) and Kabini, which supply water under the Cauvery Water Supply Scheme.
How much water do Bengaluru residents get?
According to BWSSB data, the people of Bengaluru get roughly 1,450 to 1,500 million litres per day (MLD) of treated drinking water from the Bangalore Water Supply and Sewerage Board. This helps in serving around 1.4 to 1.5 crore people. However, not every resident of Bengaluru receive the same supply of water and it largely depends on which area a person is living.
Unlike many other cities such as Mumbai, Bengaluru's fortunes depend largely on the health of the Cauvery basin. Even if rainfall within the city remains below normal, adequate precipitation in the Cauvery basin can help it maintain its water supplies. However, a weak monsoon would put pressure on Bengaluru's water availability.
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