The groundwater level in South Delhi has plunged to an alarming 66.7 metre at its deepest, the second-worst in the whole of the National Capital Region after Alwar (79.75m). Parts of South-West and West Delhi have also reported the highest salinity levels in the entire region setting alarm bells ringing.
With groundwater levels in Delhi and the rest of the NCR not only depleting at an alarming rate, but heavy contamination and poor quality making it severely unfit for consumption, the National Capital Region Planning Board (NCRPB) has cautioned that groundwater resources in the NCR are under pressure on account of “over-exploitation”.
In its draft revised regional plan 2021, the Board claims that groundwater contamination is also an area of concern apart from plunging levels.
“As per the Central Ground Water Board [CGWB], the stage of groundwater development in the NCR [ratio of annual draft to net groundwater availability] in 2009 was about 103 per cent compared with 61 per cent for India as a whole. This shows that there is an imbalance between the net annual recharge and withdrawal in the NCR, indicating very clearly that groundwater withdrawal significantly exceeds the rate of aquifer recharge,” the Board said in the report.
Of all the sub-regions, the situation is better in the Uttar Pradesh sub-region where the stage of groundwater development is 79 per cent, but that too is higher than the all-India figure of 61 per cent.
While Haryana has the highest number of over-exploited groundwater development blocks at 22, Delhi comes second at 20, followed by Rajasthan at 14 and Uttar Pradesh at nine.
With demand for drinking water on the rise and growing dependence on groundwater to bridge the demand-supply in the region, the NCRPB has proposed urgent steps to increase groundwater recharge to compensate for annual groundwater withdrawal.
“The depth of groundwater table [pre-monsoon] varies widely across the NCR from about 0.1 m below ground level [BGL] to 80 m BGL. The minimum depth of the water table has changed negligibly during the last four years — 2007-2011 [from 0.08 m in 2007 to 0.10 m in 2011], while the maximum depth has increased from 62.76 m to 79.75 m [that is 27.07 per cent] during the same period. The average depth of the water table during 2007-2011 varied between 11.43 m to 12.49 m. The deepest water table was recorded in Alwar [79.75m], followed by South Delhi [66.7m],” the report claimed.
“Salinity of the groundwater exceeds the permissible limit [3,000 ìS/cm] in many parts of the NCR, rendering the groundwater unfit for drinking. Of the cumulative 775 groundwater samples collected and tested during 2007-2011 in the NCR, 177 samples, about 23 per cent, showed salinity values above the permissible limit. The highest value of 16,700 ìS/cm was recorded in 2011 at Kair in South-West Delhi, followed by Hiran Kudna in West Delhi [14,100 ìS/cm],” the report said.
Excess chloride content [above 1,000 mg/l] in groundwater was recorded in eight districts during 2007-2011, of the 18 districts [eight districts in Delhi, seven districts in the Haryana sub-region, one district in Rajasthan sub-region and two districts in U.P sub-region] monitored by the CGWB during the period 2007-11. For presence of fluoride in groundwater, excess content [above 1.5 mg/l] was recorded in 13 districts. Nitrate contamination was found in 16 of the 18 districts, while excess iron content was recorded in monitoring stations of six districts of the NCR — five districts of Haryana sub-region [Jhajjar, Gurgaon, Panipat, Rohtak and, Sonepat] and Alwar District in Rajasthan.
Groundwater is saline in several parts of the NCR, the report claimed, pointing out that this water is not being used even for salinity-resistant crops.
“Utilisation of saline water after appropriate treatment and blending can be another potential source of water for the NCR,” the Board has suggested.
Making a pitch for groundwater recharge and rainwater harvesting, the Board has suggested that surface run-off is recommended to be harvested by increasing recharge in the basins through various induced recharge techniques, roof-top rain water harvesting, etc.
“Water recharging areas and floodplains should be preserved. It is recommended that unused floodwater be utilised to increase the recharge in floodplains of the Yamuna, Ganga and Hindon. There are several floodplain harvesting techniques such as basin spreading technique, stream channel recharge technique, induced recharge through pumping from a surface source into aquifer, construction of check dams in river channel upstream of the channel bifurcation, etc.”
