To prevent recurrent monsoon flooding that brings India's metro cities to a halt, adopt the watershed approach

The horror of Chennai floods was still fresh in the mind when severe flooding crippled the millennium city of Gurugram and struck Delhi, Mumbai and Bengaluru. Rain for only two hours paralysed life in glittering Gurugram, with knee-deep waterlogging forcing authorities to shut down schools and offices declaring a holiday. It is a reality of unsustainable urban development that population growth and visionless race for infrastructure is disturbing the natural equilibrium and worsening quality of life for urban residents.

Master plans have failed in our country because they are rigid, obsolete and unable to cope with the pace of growth of Indian cities. Traditionally, colonies and residential areas have been the unit of micro-level planning within city limits. Planning has focussed on providing civic amenities like water supply, electricity, road connectivity and sewage facilities to residents of an area. In cities like Gurugram, the focus of water supply schemes has been to lay down pipelines, import water from outside city limits and supply it to residents.

While this is a convenient approach to solve water scarcity within the city, it increases dependence on natural resources outside the city or state jurisdiction and increases vulnerability by limiting the scope of management only to supply and not to availability of water.

Moreover, the approach of laying sewage lines to expand coverage only, disturbs the natural drainage patterns of a city and increases the incidence of waterlogging. Lack of a regional planning approach has led to haphazard proliferation of slums and other urban problems.

A watershed is a geo-hydrological unit comprising all land and water within the confines of a drainage divide. Firojpur Jhirka-Delhi ridge forms the western boundary and Delhi ridge forms the eastern boundary of such a watershed. These hills are the northern continuation of the Aravalli hills. The natural drainage pattern of the city comprises large depressions and streams, tending to converge inland instead of flowing into Yamuna. A delineation of watersheds in Gurugram district, indicate the distribution of Gurugram urban into six micro-watersheds, five of which flow northwards to Delhi. Delhi-Jaipur expressway crosses these micro-watersheds almost in the middle, and blocks the natural drainage pattern from south to north.

Adopting a watershed approach to micro-level planning in a city reduces its dependence on imported natural resources like water from outside the city limits, and also mitigates the risks of extreme weather events. While increasing the potential for water conservation options like rainwater harvesting and aquifer recharge, it is useful in efficient drainage and storm water management.

It is more important to incorporate the watershed approach within city development plans itself, especially in siting of residential colonies and other facilities. This will increase the availability of water for residential areas while reducing energy consumption in transporting water to upstream locations. It will also lead to reduction in financial expenditure for laying the pipelines.

While it is not possible to relocate the existing infrastructure of cities like Gurugram, municipal authorities should reassess the drainage network especially along the roads and highways in the context of natural drainage pattern within the micro-watershed. Locality-wise sink hole/ depressions need to be identified, and lift systems should be installed at these places for transferring water. NDMA through its guidelines for management of urban flooding, published in 2010, also recognises the significance of this approach. However, it hasn't found salience in urban development discussions among authorities.

As climate change is reality now heavy precipitation events are likely to increase. This requires city authorities to adopt an integrated watershed based approach for better adaptation of their population.

The watershed approach is being adopted across the cities of the world. The City Concept Plan of Singapore had the provision of satellite towns development around the central water catchment area. Louisville-Jefferson county in the US have stormwater master management plans. In India this approach has been applied to village level development planning. But cities too need this approach, if they are to be 'smart'.