Managing the catchment of rivers needs to figure high on the list of priorities if a city wants to be sustainable and just in its water supply, says S. Vishwanath
A city needs a vast hinterland to support its population base as well as its economic engine. From here will come the food, water and other resources to keep it going. Of these, water is a crucial limiting factor in the sense it has to be physically managed in large volumes to be delivered to every household daily.
Managing the catchment of the rivers which are the primary source of water will need to figure high on the list of priorities if a city wants to be sustainable and just.
On the other hand the city also needs large areas of land downstream to manage the vast streams of waste that flow from it. Solid waste generated needs land-fills as disposal areas. Liquid waste flowing through streams need large areas too for absorption of the nutrients.
In a strange conundrum the valley of the Vrishabhavati is one of the greenest areas around Bangalore while the surrounding areas suffer from drought and a shortage of water. The city generates waste-water in the millions and about 500 million litres per day flows out in the Vrishabhavati valley. The Byramangala reservoir, spread over 420 acres, receives all this water. It is a surprisingly scenic spot and deceptively beautiful. Built in 1940 this reservoir continues to provide irrigation water through canals to many a farm field. The reservoir itself used to be a breeding ground for fish but all that has gone with the introduction of the African catfish into it.
Downstream the waste-waters undergo a remarkable transformation. The soil, the vegetation and farmers transform this nutrient rich water into a green bounty. Slowly and surely, as the river progresses, one sees an improvement in the quality of the waters and by the time it joins the Arkavathy it can hardly be recognised as a foul-smelling black stream which leaves the city. The ecosystem service provided by nature is truly remarkable.
This is not to say that there are no problems. Industrial effluents should not enter the stream at all. Domestic sewage too should be treated to a certain minimum standards before release into the river. Groundwater in around 50 per cent of the borewells was reported as contaminated, especially with nitrates and bacteria, according to a study. Farmers and field workers too have been reported to suffer from skin disease and other ailments.
While source control and elimination of the problem there is the best way it is still true that these waters are now essential for the livelihoods of hundreds.
Can the city think of identifying the entire area of the Byramangala reservoir and its command area as a zone which produces ecological benefits and for which the city should support the land and its cultivators? Can this land be bought by the city and managed with the farmers and a palate of crops developed which will not enter the food chain of the residents of Bangalore? Can the villagers downstream be supported to access safe water and also be rid of the disease impact of using the waste-water?
Can we think other than conventional waste-water treatment plants, say vast bio-diverse managed wetlands to clean the sewage that emanates from our city and for which each and every citizen is personally responsible? Can the institutions in our city rise up to the challenge and can the city become ecological and waterwise? If any city can be the first, this city has a fair shot at it.