The Hindu 28.08.2012
Tardy monsoon: water table rises only marginally
The shortfall in rains this season has begun to have an
impact on groundwater in the city. The water level has witnessed only a
marginal rise this July compared to last year, according to a study of
Chennai Metrowater. For the past few years, the water level across the
city had risen by a minimum of 0.50 metre annually. However, this year,
there has been a rise of only up to 0.15 metre in areas, including those
newly merged with the city.
The water level in sandy
areas, including Ennore and Akkarai, has risen by 0.15 metre from 4.50
metre below ground recorded in July last year. In clay areas such as
Manali and Semmencheri, the groundwater has gone up by .10 metre from
4.30 metre last July. Hard rock areas, where percolation is relatively
slower, registered the least increase by 0.5 metre this year.
S.
Prema, a resident of Villivakkam, said that water in her well has
turned a bit hard over the past two months. She has had to use more
water to wash clothes. Residents in other areas, including
Sholinganallur, Kolathur and Valasaravakkam, also complained of a slight
increase in salinity in the groundwater.
The water
quality has also slightly dipped compared to last year. The level of
total dissolved solids, a parameter used to determine salinity in the
water, in sandy areas was 200 parts per million (ppm) last year. This
July, the TDS level across the city ranged between 400 ppm and 1,300
ppm.
Sources in the Metrowater said while water with
TDS up to 500 ppm is considered fit for drinking, the permissible limit
for TDS in water is up to 2,000 ppm.
Metrowater
monitors the water table and the quality of water in 80 observation
wells spread over the city, including the merged areas. The wells are
located every 3 sq.km. or 5 sq.km.
Rainwater harvesting
Harnessing
every drop of rain gains significance as the water table has shown only
a marginal rise. This year, Metrowater has turned its focus on added
areas and insists on installation of rainwater harvesting structures. It
has initiated random checks both in merged areas and the city. “We
found that only a negligible percentage of the buildings checked have
not maintained their structures properly,” said a source.
The
water agency is in want of more manpower to conduct a detailed survey
on the maintenance of the rainwater harvesting structures in the
expanded Chennai Corporation. There is a proposal to rope in volunteers.
Metrowater
is also in the process of writing to heads of 64 government departments
to check and maintain their RWH structures. Residents may contact the
Metrowater office at 28454080 for free consultation.
