Encouraging ground reality in city
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There has been a remarkable improvement in the groundwater table in Chennai, thanks to the copious northeast monsoon flows of 2005. A survey by T. RAMAKRISHNAN
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The results are out and they convey a very positive picture. There has been a remarkable improvement in the groundwater table of Chennai following the bountiful northeast monsoon of 2005. A comparison of the groundwater level data in different parts of the city in January this year with that of the previous years clearly shows the tremendous increase in water table this year.
Average groundwater level in the city has risen to 2.1 metres in January 2006 from 5.4 metres exactly a year before. It fell to as low as 6.56 metres in 2004, considered the worst year in recent times. In January 2003, the level was somewhat close to the present one at 3.36 metres.
Dramatic rise
That's at the macro level. If one were to go by zone-wise data (see graph), the rise in the groundwater levels is there for all to see. Some of the most congested pockets of the city - Royapuram, George Town, Kodambakkam and T. Nagar have seen a dramatic rise in the levels.
Two years ago, the average groundwater level in Kodambakkam and T. Nagar (both come under the Zone - VIII) was 7.71 metres. This was the worst water level for any zone then. But, this year, the same areas witnessed the groundwater level going up and remaining at 1.25 metres. The zone saw a rise of nearly 5.5 metres in one year.
In respect of Royapuram and GT, perhaps the most densely populated part of the city, the situation has not improved to the same extent as in the southern parts. This year, the mean level was 2.47 metres whereas it was 7.09 metres two years ago and 6.44 metres last year.
The best levels were recorded in the northern and southern extreme zones (Zone I and X) with 0.84 metres and 0.9 metres respectively. One common feature is that they are predominantly sandy areas. The improvement is not just confined to the levels. It is also evident in respect of the quality of groundwater according to official data with Chennai Metrowater, which regularly monitors the groundwater levels.
In January 2005, the level of Total Dissolved Solids (TDS), an index of water quality, was as high as 3,800 parts per million (ppm) in sandy areas of the city, whereas this year, it was just 200 ppm. Tondiarpet, Washermanpet, Royapuram, Park Town, Triplicane, Mylapore, Besant Nagar and Thiruvanmiyur are classified as sandy areas.
Lower extraction and RWH
As for clayey areas, the corresponding TDS values were 2,100 ppm and 100 ppm. Among the clayey areas are T. Nagar, West Mambalam , K.K. Nagar, Vadapalani, Villivakkam, Choolaimedu and Anna Nagar.
In hard rock areas such as Velachery, Saidapet and Guindy, the TDS values were 2,200 ppm and 100 ppm for January 2005 and January 2006 respectively. High rainfall, and the consequent lower extraction of groundwater have contributed to the present situation. But, there is one more factor that is responsible, say Metrowater officials.
Rainwater harvesting (RWH) structures are there all over the city and this has left a positive impact. The officials substantiate this by citing the values of TDS obtained during the pre-RWH regime. (It was in 2003 that the Government carried out an intensive drive, calling upon people to install RWH structures.)
Prior to 2003, on an average, the TDS values in the post-rainy season for sandy, clayey and hard rock areas were in the range of 400 ppm - 300 ppm. Emphasising on the need for sustaining the situation, the officials say that the focus is now to maintain the RWH structures properly. Filter medium has to be cleaned now so that any rain during summer can be harnessed.
Judicious use will help
Experts stress that though the situation is improved now citizens should still be judicious in the use of groundwater. Though it has become natural for any Chennaiite to rely on groundwater to meet his or her immediate needs, the resource is not something that one can keep on drawing for ever.
Already, some parts of Chennai metropolis — Minjur and Besant Nagar — have shown their vulnerability. In these areas, groundwater has become saline thanks to indiscriminate and mindless extraction. So, when Chennaiites are enjoying a comfortable water supply position, they should not lose sight of the importance of proper use of groundwater, water experts say.
The experts also emphasise that the authorities too should carry on their campaign of advising the people to treat groundwater as a resource that is not inexhaustible.
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