No new reservoirs & allowing builders to flout rules for a quick buck has endangered the groundwater table of the city & surrounding districts
Chennai’s residents are parched and angry, spending large parts of their income on water for both drinking and for daily needs in the fourth year of drought.
What has now come home to roost is the corruption of many decades, especially in the wake of the real estate boom.
History teaches us many lessons and The Lede takes you through the journey of the city’s water supply system for the reader to understand when and how things began to go badly wrong.
Own wells, public wells and community tanks were once the source of water in Chennai. This was in the period of the British Raj, up until about 1870.
In 1872, the first project was taken up by a British civil engineer, Fraser. He built a weir to a height of 1.8 metres across the Kosasthalaiyar river in Tamaraipakkam. The water from the river was then diverted to Cholavaram lake and from there to Red Hills lake from which it flowed to Kilpauk in the city. Fraser made use of the lie of the land and gravity aided the flow of this water. From Kilpauk, cast iron pipes were laid and this water was then distributed to the neighbouring areas.
As the First World War was on, in Chennai, the first purification system of water was put into place. This was 1914. Underground conduits were built instead of the open channels and the raw lake water was taken to four underground storage tanks where the water was filtered using slow sand filters. This project was taken up by a British engineer James Wilby Madeley after an Indian engineer Hormusji Nowroji completed 45% of the works. From here the water was pumped using four steam engines to overhead steel tanks in Kilpauk and then distributed to the city. The works were completed in 1870 at a cost of about Rs 18.5 lakhs.
According to Metrowater, Madeley considered this “sufficient for an anticipated population of 6.6 lakhs in 1961 at 25 gallons per head per day. But the need for further improvement was felt in 1936 itself.”
It was around the Second World War that the next milestone was achieved in Chennai’s water supply system. The Poondi reservoir was constructed in 1944 to store river from the Kosasthalaiyar.
According to the Metrowater website, the combined storage of three lakes at the time i.e. Poondi (2573), Cholavaram (583) and Red Hills (2440) was 5596 mcft.
The combined capacity of Cholavaram and Red Hills lakes were increased by 700 mcft by increasing the height of the lake bunds around 1972. This took the storage of all three reservoirs to 6296 mcft, with Poondi holding 2573 mcft, Cholavaram holding 881 mcft and Red Hills holding 2842 mcft.
“The irrigation rights of Cholavaram lake and Redhills lake were acquired in 1962 and the entire storage was made available for the City supply,” according to the Metrowater website.
In 1978, the city’s first Master Plan for water was drawn up. This was the first time that the river Krishna was identified as a potential water source for Chennai. Groundwater acquifers were also identified in south Chennai between 1973 and 1984. 10 MLD of water from this groundwater acquifer was supplied to Thiruvanmiyur, Tamil Nadu Slum Clearance Board tenements at Okkiyam Thoraipakkam and Aavin.
“In order to avoid sea water intrusion due to depletion in water level, the present drawal has been restricted to only 1.5 MLD,” according to Metrowater.
In 1987, more acquifers were identified in north Chennai to extract groundwater for the city’s growing population. Between 1982 and 1985, another UNDP project identified three additional well fields in Poondi, Kosasthalaiyar flood plains and Kannigaiper which could bring about 55 MLD to the city. This was one of the key features of the First Chennai World Bank Aided Project in 1987.
“From the three surface sources (Poondi, Cholavaram and Redhills) and 6 ground water well fields (Minjur, Panjetty, Tamaraipakkam, Poondi, Flood Plains and Kannigaiper), about 318 MLD of water was abstracted of which 273 MLD was supplied to Chennai City at an average of 70 lpcd and 45 MLD supplied to Industries in Manali area till September 28, 1996,” according to Metrowater.
From the 1980s onwards, the city’s water supply began to depend increasingly on groundwater. As the years passed, more and more acquifers were identified and tapped as the city exploded in terms of population and real estate development.
United Nations Development Program studies were carried out between 1966 and 1969 to ascertain the groundwater acquifers present in north Chennai. Based on these, Tamaraipakkam, Panjetty and Minjur were identified in the Araniar-Kosasthalaiyar basin as well fields for extraction of groundwater at the rate of 125 million litres a day (MLD). This groundwater was partly added to the city’s water supply system from 1981 onwards.
In the 1990s, there were two proposals for new reservoirs which would augment the city’s water supply. Both of these were upstream of Poondi – in Ramancheri and Thirukandalam.
“The proposals were all in place and these reservoirs were to be built across the Kosasthalaiyar,” said S Thirunavukkarasu, retired PWD (Public Works Department) engineer. “But there were small villages there and they had to be resettled for this project to take place. Since there were protests by these villagers, the government was reluctant to do anything. As a result, the proposals were dropped,” he said.
Another proposal passed through various files and hands regarding the setting up of a reservoir of 1.5 tmcft over the Adayar river at Thiruneermalai in Chennai city. “But by the time it was ready for approvals, the entire area was fully built up,” he said.
Today, according to the Managing Director of TWAD Board (Tamil Nadu Water Supply and Drainage) CN Maheshwaran, 53% of the state’s water demand is met by surface water while the remaining 47% comes from borewells – close to half the population of the state is depleting groundwater at an unstoppable pace.
From the mid to late 1990s onwards too came a boom in the real estate and construction industry. On one hand, policymakers had not envisaged a Chennai that would exponentially increase in population. This led to no further surface water resources being added to the city’s water supply.
On the other hand, personal cash registers were ringing nonstop as the real estate boom ushered in corruption at every certificate, licence, clearance and permission.
And this meant of course, that builders could run riot and do what they pleased as the authorities meant to oversee them simply looked away. Conservation measures took a hit as builders looked to build on every inch of their plots, throwing to the wind practices such as putting in place proper rain water harvesting structures or giving breathing spaces for water to percolate into the earth.
For instance there are rules stating how much plot coverage area should be for all buildings in Chennai. The CMDA defines plot coverage as “the extent to which the plot is covered with a building or structure (12-noon shadow) and this is expressed as percentage of the ratio of the built up area to the plot area.”
As far as Chennai is concerned, the plot coverage ranges from 70% to 75% for different categories.
“This is to ensure that groundwater percolates into the soil and recharges the table,” said Thirunavukkarasu. “But most of the buildings don’t follow this rule at all. The little space that they leave around the buildings is also concretised. How will rain water percolate? The problem that we are facing today is due mainly to corruption of so many decades,” he said.
A senior official at the CMDA told The Lede that there are around 15,000 multi-storied buildings and one lakh buildings with three stories in Chennai. “The RWH (Rain Water Harvesting) structure is not a one-time investment, it requires renewal at least once in three years,” he said. “Secondly even though open space is available around buildings, most of it is concretised. This reduces percolation,” he added.
The official also stressed upon the need for residents to start using recycled water. “Time has come that people and policies need to aggressively promote treated water at least for uses other than drinking and bathing,” he said.
As the city grew towards the south, water supply was not provided by the state government. Areas like Madipakkam, Okkiyam Thuraipakkam, the IT Corridor on the Old Mahabalipuram Road, all depended on borewells, with residential complexes sucking out groundwater at a furious pace.
“Right now the deep water acquifer which is called fossil water and which takes a long time to get accumulated, is depleted and is going to take many more decades to get back,” said Indumathi Nambi, Professor, Dept of Civil Engineering (Environment and Water Resources), IIT Madras.
“We have to bank on shallow water and surface water. It takes a long time for water to percolate and reach that level. If you are going to drill through the rocks and penetrate deeper and deeper, the fossil water is going to deplete. It is like mining coal or petroleum reserves – it takes a long time to replenish. This is a little scary.
If we do something proactively - and already some lakes have been rejuvenated - and if we take serious efforts to replenish the deep acquifer, we might recharge it over some decades but at this rate it cannot last much longer,” she said.
On 14 April 1976, an agreement was signed between the governments of Maharashtra, Karnataka and Andhra Pradesh to provide 15 tmcft of water from the river Krishna to Chennai.
On 18 April 1983, an agreement was signed between the Andhra Pradesh and Tamil Nadu governments for the latter to draw 15 tmcft of river water from the Srisailam reservoir in Andhra via the Somaseela and Kandaleru reservoirs to the Tamil Nadu border. The loss due to the transportation was pegged to be around 3 tmcft.
From September 1996, Krishna water was flowing into the Poondi reservoir from Kandaleru in Andhra Pradesh through the 152 kilometre long open canal. From Poondi this water goes to Red Hills and Chembarambakkam and is distributed to the city.
In 1996, the first Master Plan for water for Chennai city was updated. Water supply had increased by 930 MLD thanks to the Krishna water scheme. Storage capacity of the lakes was also increased.
Once the 1991 census was published, the Master Plan had to be updated with requirements for the population. The assessment for the year 1996-97 was as follows:
The last project for storage of water for the city was commissioned in 2004.
The Veeranam water supply project was commissioned to bring 180 MLD of water to Chennai from the Veeranam lake in Cuddalore district, over 230 kilometres from Chennai city.
Through this scheme, the city would get a share of Cauvery river water that irrigates the delta regions of Tamil Nadu. The Veeranam lake has a capacity of 1465 mcft.
By 2010, it had become essential to think of other sources of water. A desalination plant of 100 MLD capacity was commissioned in July 2010 near Minjur.
In 2013 another 100 MLD desalination plant was set up in Nemmeli on the East Coast Road of Chennai.
Now the Chennai city Corporation is planning to set up three small desalination plants within the city to meet the water crisis.
“Instead of conserving flood water, you want to go for high cost high technology solutions at the cost of coastal ecology,” said Professor Janakarajan, President of SaciWATERs, an expert on water and hydrology. “If the Middle Eastern countries where the rainfall is 200-300 or 400 mm resort to desalination plants, I support them. With the kind of rainfall we get, why do we resort to desalination plants? It is completely irrational,” he said.
“We are trying to get water from Telugu Ganga, Veeranam but it is useless. It (this water) is not for the city, it is for the hundreds and thousands of farmers who live along the rivers. After the 2015 flood, the average rainfall of the city has changed to 1400 mm which is very very good rainfall. We should be able to conserve it,” he added.
Here is a table of the increase in water supply from the Chennai Metropolitan Water Supply and Sewerage Board since its formation in 1978.
If Chennai must survive more such summers, it is imperative for its political leaders to have vision that goes beyond the next election. Long term sustainable measures to conserve rain water, reining in corruption and proper implementation of long pending lake desiltation & rejuvenation projects are crucial.
And if the political leaders do not make this a priority, it is incumbent upon the people to ensure that they do so. If people too buy real estate that flouts the rules, drill deeper for precious groundwater, unmindful of the generations to come, Chennai will suffer.
(The CMDA’s response has been added to this story. An earlier version of this story said that the CMDA did not respond.)