The Hindu 04.08.2017
Metrowater plans rainwater harvesting audit
Earlier sample study found poor maintenance in 30% of structures;
Existing mechanisms have potential to add 2.7 tmcft to groundwater every
year
In
an effort to assess the impact of rainwater harvesting (RWH) measures
and ensure water security in Chennai, Chennai Metrowater is planning to
conduct an audit of RWH structures across the city. The exercise is
expected to begin in a couple of weeks.
The water agency plans to
have the audit with community participation and support from voluntary
organisations as it does not have sufficient manpower on its own.
According
to Metrowater’s data, there are nearly 8.62 lakh RWH structures
installed in the buildings across the city. During the last fiscal,
15,200 structures were constructed as it was mandatory for obtaining new
or renewal of water and sewer connections.
Metrowater officials
said if the RWH structures were found to be poorly maintained, residents
would be sensitised about the need for maintenance. Bulk consumers like
hospital and educational institutions would be asked individually to
maintain such structures. “We have to decide on the methodology to be
adopted for the audit. The options of using digital technology are also
being considered,” said an official. Residents could also attend
awareness meetings planned by the Metrowater in various areas.
Metrowater
is also planning to strengthen its hydro-geology wing by recruiting or
outsourcing services of graduates from Anna University. The team would
be used to map the city’s aquifers, identify new water sources and also
encourage implementation of greywater recycling in Chennai’s buildings.
Design change
An
audit of RWH structures taken up by Rain Centre, a city-based voluntary
organisation two years ago, is perhaps the only comprehensive audit
available so far. The organisation was assigned the project by the
Chennai Metropolitan Development Authority (CMDA).
The audit
covered 1,200 households spread over the city with sandy, clayey and
rocky soil. Kottivakkam, Anna Nagar, Thiruvanmiyur, Velachery and
Tambaram were some of the areas covered. Sekhar Raghavan, the Centre’s
director, said: “We were asked to conduct the audit in fast-developing
added areas. We found that 90% of the households had RWH structures.
But, 30 % of them were poorly maintained. Many multi-storeyed buildings
did not have RWH structures.”
Some of the recommendations included
change in RWH structure design and implementation of water metering
system. The recommendations are waiting to be incorporated in the
Development Control Regulations of CMDA.
Installing rainwater harvesting structures has also gained momentum in town panchayats.
According to sources, nearly 24.31 lakh buildings in town panchayats across the State have constructed such structures.
Across the State
Though
it was estimated that recharge potential would be increased to 4,800
million cubic feet as most buildings in the State claimed to have RWH
systems, the water table dipped up to 16.5 feet this year in some parts
of the State.On the impact of RWH, Mr. Sekhar Raghavan said percolation
pits that are suggested by the government agencies would need to be
replaced with recharge wells as pits get silted up and cannot be reused.
Environmental
activists also noted that the misuse of water bodies has led to the
depletion of groundwater resources. Kanchi Amudhan, convenor of Palar
River Protection Movement, said that deliberate breaching of bunds of
smaller water bodies has compounded the problem further.
( With additional reporting by V. Venkatasubramanian )