Integrated Urban Water Management -IUWMJuly 24, 2012
Integrated Urban Water Management
The first week of a slightly delayed monsoon has been completed and rainfall 36 % less than normal has been reported. While this in itself a cause for major worry as according to the Indian Metrological Department the subsequent rains may make up for the shortfall it is time to understand the dependency of our cities on rain. Most urban areas now start to draw water from over a 100 kilometres. Cities like Chennai, Hyderabad, and Bangalore have large ‘water footprints’. Coimbatore was struggling to supply enough water to its citizens as the reservoir on the Siruvani was depleting fast and had enough water for just 15 days.
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. 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 to depend on one utility or the local government to be the only solution provider.
On the World Environment Day June 5th I was at the Volvo Construction Equipment factory in a suburb of Bangalore. Many in the team planted trees but what was striking was the effort put in 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 4 months of the total water requirement of the unit. There is also recharge of groundwater which enables the 3 bore-wells 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 Integrated Urban Water Management in practice.
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 they have 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 .
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 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 it to become a bio-diversity and recreation zone but also be functional by recharging groundwater and enabling it to be drawn through wells and bore-wells for further reuse.
The process of IUWM is one of keeping catchments and aquifers clean, understanding and working with the hydrological cycle at play in urban areas, 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 proper source control and management of water, managing aquifers through traditional structures such as open wells and modern ones such as bore-wells. A city like Bangalore has approximately 3000 million litres per day of water falling on it in 60 rainy days. The demand for water is about 1800 million litres per day. By taking responsibility for the rainwater and waste-water , by ensuring harvesting, recharge and treatment , by protecting urban water bodies and by appropriate 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 for it. IUWM is the process of translating that responsibility to 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.