In populated metropolitan cities, the primary sources of water include groundwater and lakes. Groundwater is harvested with the help of borewells whereas pipes harvest water directly from the lakes. The harvested water is then stored in water tankers placed at strategic locations throughout the city. 2. Compare the above system with the probable systems in hilly/ mountainous areas or plains or plateau regions. Solution In hilly regions, rainwater is often collected and channeled with the help of a stream. The stream is diverted to different areas with the help of canals for the purpose of irrigation. In mountainous regions, water is commonly obtained from the rivers that flow from the glaciers. In the plains, water is obtained from many natural sources such as lakes and rivers. Groundwater is also harvested with the help of borewells for irrigation and human consumption. 3. Find out the source of water in your region/locality. Is water from this source available to all people living in that area? Solution
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At a time when most people in the city are scrambling for water and pinning their hopes on tankers to quench thirst, an apartment complex on Greenways Road has not bought a single tanker load this summer — the reason being the availability of groundwater and better rainwater harvesting techniques.
Desilting an open well on the premises and cleaning of recharge wells have helped residents avoid being dependent on tankers or Metrowater supply the last few months.
A.K. Subramanian, a resident of Greenways Road, said: “We still have groundwater at 20 ft and we draw 60,000 litres daily to supply 110 apartments. It was possible because of proper harnessing of rainwater. Piped water supply stopped two months ago.”
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A majority of the buildings in the city have rainwater harvesting structures in place since 2003, when the State made it mandatory. But many in the urban areas still do not have their own source unlike the apartment complex on Greenways Road, as they have either adopted wrong RWH methods or are not maintaining the structures, note experts.
Keeping tabs
According to Chennai Metrowater records, there are nearly 8.9 lakh rainwater harvesting structures in various types of buildings across the city. However, there is not enough data on the maintenance of such structures, except for random checks before the northeast monsoon and the RWH audit done by the Rain Centre in suburban areas.
Metrowater officials said it was imperative to harness rainwater in June, as structures would be nearly 100% efficient as parched land would absorb more water.
The average groundwater level in the city has dropped to 7.7 m. This is still better than 2003 when the city was reeling under acute water crisis, given the population growth and urbanisation, an official said.
While several commercial and residential establishments are waking up to rainwater harvesting, many buildings continue to implement wrong RWH methods, and are instead preparing to sink deeper borewells in search of water.
Residents of an apartment complex in Padur, OMR, now plan to install RWH structures to save rainwater.
V. Ravindran, president of the Color Berry Apartments Residents’ Welfare Association in Padur, OMR, said: “Our builder did not provide any RWH structures and we are spending ₹30,000 every month. We don’t have any other source of water and borewells have gone dry. We want to become self-sufficient with natural resources.”
Rain Centre, a city-based voluntary organisation (ph: 9677043869), has been receiving enquiries from residents on how to enhance the groundwater source.
Responsible shift
Sekar Raghavan, its director, said: “Several people, particularly in large complexes, are now shifting to recharge wells voluntarily, as there is growing awareness on RWH. If 80% of the city does RWH correctly and maintains the structures, we will be able to tide over the water crisis.”
He recalled the audit done a few years ago in 1,384 units in the suburban areas where 52% of multi-storied buildings did not maintain RWH structures.
The audit also indicated that 45% of government institutions surveyed did not maintain them.
“It will take one or two years for a visible change in groundwater levels, as people are volunteering to harness water. People in congested areas and along the OMR, where the demand for water is more, must store rainwater in sumps,” he added.
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