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A new hydrology model-based study has proven a clear correlation between urbanisation and a decline in groundwater reserves in five Indian states.
The paper, titled Detection and Socio-economic Attribution of Groundwater Depletion in India, was published in the journal Hydrogeology Journal. Gautam Kunwar, the lead author and currently a researcher at the University of Texas, Austin, said few studies in India have connected groundwater depletion to the rapid pace of urbanisation.
The northern and northwestern hotspots have suffered a staggering loss of approximately 64.6 billion cubic metres of water over the past two decades, Kunwar added.
The study utilised data from the Central Groundwater Board (CGWB) from 2003 to 2020 for this analysis. In addition to the CGWB report, the study sourced data from the India Meteorological Department to examine changes in rainfall patterns over the same period.
Data from GRACE (Gravity Recovery and Climate Experiment) was used to estimate total water reserves, and groundwater storage simulation models were also employed. The study raises serious concerns for five hotspots: Punjab and Haryana (Hotspot I), Uttar Pradesh (Hotspot II), West Bengal (Hotspot III), Chhattisgarh (Hotspot IV) and Kerala (Hotspot V).
Punjab and Haryana were the most affected areas, according to the study, showing the highest decline in India. Not just irrigation, urbanisation and industrialisation are equally responsible for the plunging groundwater levels in these two states. This is evident in the groundwater decline observed in Faridabad and Gurgaon, Haryana, predominantly urban areas with minimal agriculture, where groundwater levels began dropping post-2012.
The level of urbanisation between 2001 and 2011 increased by 10 per cent, from 10 to 20 per cent, and that during the same period, there was a significant growth in the number of factories, the study highlighted. A drop in net annual groundwater availability between 2004-05 and 2018-19 by 4 per cent coincides with increased industrialisation in these two states, with the correlation further strengthened by the fact that there has been no decline in rainfall during this period.
Among the other four hotspots, Chhattisgarh showed increased irrigation, domestic, and industrial use as the cause of reduced groundwater availability. However, the states of Uttar Pradesh, West Bengal, and Kerala told a different story. Uttar Pradesh, marked as Hotspot II by the authors, saw an 8 per cent decrease in groundwater demand for irrigation between 2004 and 2020, while domestic and industrial use increased by more than 38 per cent over the same period, leading to a 4 per cent drop in net annual groundwater availability.
In West Bengal, during the same period, the study found minimal growth in groundwater demand for irrigation (0.09 per cent), while domestic and industrial use surged by 24 per cent, resulting in a 3 per cent reduction in net annual groundwater availability. Kerala, despite being a coastal state that receives significant rainfall, shows no respite.
Between 2004 and 2020, the state experienced a 17 per cent decline in net annual groundwater availability—the highest among the five hotspots. Groundwater demand for irrigation dropped by 36 per cent during this period, while domestic and industrial uses increased by 34 per cent.
The government has already begun implementing groundwater recharge projects across the country, with some positive results, said Manabendra Saharia, assistant professor in the Department of Civil Engineering at the Indian Institute of Technology, Delhi, and the second author of the study.
However, the main issue is the lack of groundwater recharge in urban areas, which is leading to the depletion of groundwater levels and land subsidence, Saharia added. He suggested that wetland restoration in cities should be aggressively pursued to improve urban groundwater reserves.
