Homes and gardens

The city’s future

Should we opt for large-scale inter-basin transfer of water or simpler solutions such as RWH? By S. Vishwanath

As the rains of August finally arrive over the city, the question is will it bring relief to the water stress that the region faces? The four major reservoirs of the Cauvery are at historically low levels and there is trouble brewing for the future.

The city of Bengaluru is an economic and population powerhouse for the State and both the economy and people need water. Projections suggest that the city will need close to 4,000 million litres per day of water by the year 2050 as against the current 1,400 million litres per day being pumped into it. This water comes from a single source which is 95 kilometres away and 300 metres below the city, making it a hugely energy intensive and costly affair.

Where will water come from in the future? Will the needs of the surrounding greater metropolitan region be considered? Farmers, small towns, special economic zones, the airport? What will the over 8000 square kilometre of essentially semi-arid land with depleted groundwater do?

Gigantism

Two sets of answers are emerging and they challenge each other. One involves large scale inter-basin transfer of water, the conventional supply side approach increasing the already enormous ecological and energy footprint of the city.

The Cauvery 5th stage will bring an additional 775 million litres per day from the current source. The project is estimated to cost well over ₹ 6000 crore. Then there is a proposal to build an additional dam on the Cauvery at Mekedatu, create a reservoir and pump 500 million litres of water per day to the city from this reservoir. A third project looks at bringing water from the Linganamakki reservoir on the Sharavathy, transporting the water over 380 kilometres. The project is estimated to cost ₹ 10,000 crore. A project called Yettinahole, which involves diversion of parts of the flow of a west flowing river to the east and bring water to the farming communities of Kolar and Chikballapur and some for the city of Bengaluru, is already in progress. Finally, there is a proposal to store the fresh water flows of the Nethravathy in the Arabian Sea and then to pump it to the city for a distance of about 350 km.

Meanwhile projects are on to pump secondary treated waste-water to fill the tanks of Kolar, Chikballapur and Bengaluru (Rural ) districts and provide water for agriculture. Over 750 million litres will be pumped from the sewage treatment plants of the city to hundreds of tanks.

Small is beautiful

The other set of solutions looks at rainwater harvesting. By distributed collection of rainwater in individual buildings and in the lakes of the city, by recharging groundwater it suggests that the city can double its current water supply and actually tap into at least an additional 1,500 million litres per day equivalent. This solution also looks at reusing treated waste-water, either for non-potable use through dual pipelines or for indirect recharge of lakes through wetlands. Finally demand management, reducing demand to its optimal through leak reduction, water efficient devices, consumer education and pricing of water.

Apart from the huge sums of monies involved, the approach that the city takes will have large consequences on the environment, the growth of the city, livelihoods and energy used.

Do we have the right frameworks to evaluate the projects and the consequences? Can we insulate them, at least partially from hasty short-term political decisions which will bind and lock us to a long-term project? The answer is a clear no.

In the end the governance of water, the creation of the right participatory and democratic framework, the weighing of pros and cons of every decision carefully and transparently and then arriving at a decision is the challenge. The livelihoods, economy and the very environment is at stake. Hope we have the wisdom to be water wise.

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Printable version | Feb 22, 2020 10:14:34 PM | https://www.thehindu.com/life-and-style/homes-and-gardens/the-citys-future/article19474412.ece

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