With plugging of leakage & rain water harvesting, Bengaluru may not need Cauvery water

Bengaluru: During last year’s harvest season, thousands of South Karnataka’s farmers from districts like Mandya were hundreds of kilometers away from their homes. They were climbing the hills of Belagavi up in the north, trying to block the chauffeur-driven VIP vehicles rolling on to a seat of the state legislature, only to get beaten up by the police later.

It was a desperate measure to seek the attention of the state’s politicians towards their plight—an estimated 1,300 farmers killed themselves in Karnataka last year alone because of a collapse in income more than anything else, which was succinctly put by a farm union leader to Mint then: “We have told our families not to wait for us.” This time around, the roles are reversed. The politicians in the same chauffeur-driven cars are visiting districts like Mandya, where they are greeted by the Cauvery protestors. Some are even flying in on helicopters. Even the local movie industry’s stars have came down to earth to join hands with farmers.

It is a surreal scene, actually.

At the heart of the matter is the release of Cauvery waters to Tamil Nadu, which Karnataka farmers think is an indiscriminate allocation because the state is also facing a severe shortage of even drinking water, forget that for irrigation. But as some would argue, the role of a burgeoning Bengaluru in creating these water shortages cannot be ignored. Bengaluru depends heavily on Cauvery, and if Karnataka’s farmers want to fight with anyone for Cauvery waters, they should perhaps do it with the city’s planners, analysts say.

What’s wrong with Bengaluru?

The story of the Cauvery dispute is closely connected to the story of Bengaluru gradually coming to be known as a ‘Garbage Nagara’, a city of garbage, from a Kalyana Nagara, a city of water reservoirs, according to water experts. Bengaluru is located at an elevation of 900m above the sea level on a hard rock (granite-gneiss) terrain and has always been a city of rapid development. However, the city has no perennial river flowing within its 100km vicinity to supply water.

The early founders and the colonial rulers of Bengaluru plugged this crucial hole through building a strategic network of lakes, says scholar and writer Harini Nagendra in her 2016 book Nature in the City. There were as many as 19,800 lakes in the erstwhile Mysuru region, of which Bengaluru was also a part of, according to the book. But after facing a near-drought situation in 1892, Bengaluru started seeking water out of the city, which became quite a popular trend throughout the 20th century, and also saw the beginning of the water supply from Cauvery in 1969, it says.

In the 21st century, Cauvery water has surely became more crucial than anything else to meet the huge water requirements of the city, so much so that, as an Indiaspend article pointed out last week, the city consumes 50% of Cauvery water reserved for domestic use in Karnataka. This is partly owing to the sudden explosion in the city’s population over the past few decades. In the last decade alone, Bengaluru’s population increased by 65% to reach 8.5 million, the highest spike among all Indian cities, and is projected to cross the one crore mark by 2020.

Altogether, Bengaluru draws 810 MLD of water from Cauvery, but as it has been noted in several research papers before (this was reasserted both in the Indiaspend article and another one in The Newsminute last week), over out of this designed supply, nearly 49% is estimated as being lost in distribution. It’s interesting how Bengaluru plugs this shortage, which was clearly found out by two retired mining department officials and veteran hydrologists, Subhash Chandra and G. V. Hegde, in their book published last year called ‘Bengaluru Water Resource Management’.

Challenges and Remedies

Minus the shortage, the effective water supply in Bengaluru is only 318mm3/year, against a supply target of 485.45 mm3 per year (or 140 liter per day/head (lpdh)).

To plug the shortage, the city administration is extracting groundwater on a large, says the study, so much so that 12 wells dug by the mining department in 1973 to monitor ground water tables became non operational during 1985-2000 as the wells became dry or non existent. The story doesn’t end there. The department again dug a few more bore wells, in the 2000s, which also became dry by end 2010, tells the book. The results are far reaching- from having to deal with dead fish floating, fuming, frothing lakes to managing 10,000 farmers riding their tractors to the heart of the city.

Is there an alternative?

Even if Bengaluru continue to depend on Cauvery, it will not be able to meet its water demand by 2020, according to the book of above mentioned hydrologists. The water requirement for a conservatively estimated population of 9.5 million in 2020 would stand at about 1330 liter per day per/head, way above even what Cauvery could provide, says the book.

Will Bengaluru have to be evacuated by then?

No, if at least a 30% of the leakage and transmission loss is plugged, as per the hydrologists. If the administration could harvest a 50% of water in its storm water drains before it gets mixed with sewage, and if it could treat its sewage or used water up to a secondary level or tertiary level, Bengaluru will have water for at least 11 million people, they say.

There’s a rather easy way out, said Vivek Menon, who is a member at the Center for infrastructure, Sustainable Transportation and Urban Planning (CiSTUP) of Indian Institute of Science (IISc), in an earlier interview with Mint. “There are about five lakh houses in Bengaluru, each having an average roof area of 100 Sq m. With 830 mm of average rainfall per year, these rooftops could harvest about 40 mm3 of rain water. Even a 70% of it could meet the annual requirement of 6 Lakh people,” he said.

So there are ways to harness enough water from Bengaluru itself to supply for 15 million people, which can reduce the over dependence on distant river water resource like Cauvery that is core to the life of farmer in Mandya. If the money cost (Bengaluru is already spending an estimated Rs.350 crore to year to pump Cauvery water all the way to the city from 100 km away) and the social cost is factored in, it’s better to start thinking of alternatives, noted Menon.

Author: Nidheesh M.K.
 Credits Live Mint

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