As an alternative to drawing water from large distances, the concept of an Integrated Urban Water Management system has been mooted globally and is being tried out in several cities. A look by S. Vishwanath
The first week of a slightly delayed monsoon has been completed and rainfall 36 per cent less than normal has been reported. While this in itself is a cause for major worry according to the Indian Meteorological Department, the subsequent rains may make up for the shortfall. It is also time to reflect on the fact that our cities are so dependent on rain. Most urban areas now draw water from a distance of over 100 km. Cities such as Bangalore, Chennai and Hyderabad have large ‘water footprints'.
As an alternative to drawing water from large distances the concept of an Integrated Urban Water Management (IUWM) system has been mooted globally and is being tried out in several cities. This process seeks to manage the surface water, groundwater, rainwater and treated waste-water as a whole.
It seeks to close the hydrological loop at the city scale itself, if possible. If not, to reduce the dependency on external piped water supply to the extent possible. IUWM is a principle and a process and not a set-sequence of solutions. It is also a process which seeks to encourage a lot of solutions within the city rather than get dependent on one utility or the local government to be the only solution provider.
Outstanding effort
On the World Environment Day (June 5) I was at the Volvo construction equipment factory in a suburb of Bangalore. Many in the team planted trees but what was exceptional was the effort put in by employees to manage water. Below the parking area a huge rooftop rainwater harvesting tank has been created. This can hold up to 2.5 million litres i.e. every drop of rainwater falling on the large rooftops. This provides for almost four months of the total water requirement of the unit. There is also recharge of groundwater which enables the three borewells on site to provide the rest of the water needs of the factory. A 20 kilo-litre per day waste-water treatment plant treats all the effluent generated on site and this is reused for landscaping requirements and for toilet flushing. The factory has shown itself to be independent of the city's water and sanitation network and has reduced its water footprint to zero.
This is an exceptional Integrated Urban Water Management in practice.
More harvesting
There is a residential layout on Sarjapur Road which also harvests almost every drop of rainwater falling on site, prices water to control demand and recovers the monies spent on supplying it, has a waste-water treatment plant which treats and reuses all the domestic sewage generated and depends only on groundwater for its requirement from an aquifer which it has recharged. This too is IUWM in practice. Depending on local sources not only provides for independence and control but also reduces the cost of the water as well as the embodied energy.
Bio-diversity zone
Urban water bodies can all become recipients of properly treated waste-water, sometimes through wetland systems, which can then be reused as groundwater after properly testing the water quality. This means that sewage treatment plants need to be located near lakes, all sewage in the catchment conveyed to the treatment plants, the water treated and released into the lakes for them to become not just a ‘bio-diversity and recreation zone' but also be functional by recharging groundwater and enable the water to be drawn through wells and borewells for further use.
The process of IUWM is one of keeping catchments and aquifers clean, understanding and working with the hydrological cycle at play in urban areas, and aiming for universal connections so that there is social equity in access to water. It is also about celebrating water in the form of lakes and tanks, avoiding floods through source control and management of water, and managing aquifers through traditional structures such as open wells and modern ones such as borewells.
Bangalore has approximately 3,000 million litres per day of water falling on it in 60 rainy days. The demand for water is about 1,800 million litres per day. By taking responsibility for the rainwater and waste-water, by ensuring harvesting, recharge and treatment, by protecting water bodies and by garbage management, not only water but the environment can be made sustainable.
From exercising our rights to water we have also to move towards showing responsibility in using it. IUWM is the process of translating that responsibility into action. Institutions will need to change gears and invest quickly in lake maintenance, waste-water treatment and storm-water drainage. Only this will ensure that the monsoon rains are put to good use and that cities are sustainable in so far as water is concerned.
That would be water wisdom.
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Keywords: Waste water recycling, water footprints
