As the elevated tracks come up over the city a mass transport network called the metro is being built all over the city. In phases it is likely to cover over a 100 kilometre and become one of the prime modes of transport to the city. Apart from the transport benefits it will bring to the city there is one other potential benefit that could accrue to the city due to its construction.
The metro rail track offers a tremendous potential for rainwater harvesting. A total length of about 45 kilometres and a width of about 12 metres mean that the endowment of rainwater on the relatively very clean track with Bangalore’s rains of 970 mm annually is about 523 million litres. Considering a coefficient of runoff of 0.90 the harvestable rainwater is around 471 million litres annually. This could provide about 13,000 people with their annual requirement of water at 100 litres per day. A substantial sum.
Since the metro will intend to develop a small landscaped area between piers of about 25 metres and with a width of 2.50 metres, part of the rainwater could be used for this landscape purpose. The additional rainwater could be used to recharge the groundwater aquifer without causing any urban flooding.
