To resolve its unending water woes, city looks underground

Neha Lalchandani| TNN | Jul 10, 2016, 11.52 PM IST

NEW DELHI: Dependent largely on neighbouring states for water and perpetually short of meeting demand, Delhi is looking to boost supply by at least 50 million gallons per day by tapping into groundwaterresources.

With 10,285 million cubic metres (mcm) of saline water present underground, the urban

With 10,285 million cubic metres (mcm) of saline water present underground, the urban development department has asked Delhi Jal Board to look into the feasibility of setting up desalination plants. These plants will not only treat groundwater to drinking quality levels, but also open up fresh reserves present under the saline layer.

Central Groundwater Board (CGWB) has been studying groundwater levels and quality across Delhi. In a report submitted to the government recently, it has identified total groundwater availability at 13,491 mcm. Of this, 10,285 mcm is saline that CGWB says can be mixed with fresh water and used for purposes other than drinking.

“We are looking at setting up desalination plants to treat saline water. In Chennai, where desalination takes place, the total dissolved solids in water are about 15,000 ppm. In Delhi, they range between 3,000-3,500 ppm and, therefore, it will be easier to treat this water. We have asked DJB to look into this aspect,” said a senior official.

A CWGB official said that overexploitation of groundwater resources in Delhi has led to not just depletion of fresh groundwater but also resulted in deep columns of saline or brackish water. In its report, the board has recommended that the poor quality water can also be used for salt tolerant crops like cotton, wheat, guar, chickpea, soybean, sugarcane, etc.

The board has also identified 11 tehsils where groundwater levels are sufficient and can be replenished naturally for withdrawal. These include Civil Lines, Daryaganj, Sadar Bazar, Kotwali, Defence Colony, Gandhi Nagar, Kalkaji, Preet Vihar, Model Town, Connaught Place and Seelampur, which can together supply about 120 mcm water.

CWGB has cautioning against extraction of groundwater along Najafgarh drain, landfill sites and industrial belts as it is highly contaminated and not fit for drinking or irrigation without proper treatment. Four sectors – Palla-Hiranki, Akshardham Mandir-Mayur Vihar, DND flyover and Kalindi Kunj-Jaitpur – can be used for sustainable groundwater extraction. DJB already has 130 tubewells in these sectors that are yielding about 45 mgd water, but there is still scope for withdrawal of another 40 mgd.

An additional 5 mgd can be extracted from along Western Yamuna Canal where a thick column of freshwater aquifer has been identified.