Vol.:(0123456789) 1 3 Environmental Earth Sciences (2018) 77:770 https://doi.org/10.1007/s12665-018-7966-5 ORIGINAL ARTICLE GPS measurement of land subsidence in Gandhinagar, Gujarat (Western India), due to groundwater depletion Pallabee Choudhury 1  · Kalpna Gahalaut 2  · Rakesh Dumka 1  · V. K. Gahalaut 3  · Abhay Kumar Singh 4  · Sanjay Kumar 4 Received: 18 August 2018 / Accepted: 15 November 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract A continuous GPS measurement site, ISRR, at Gandhinagar (Western India), documented ~ 5 mm/year of surface subsidence rate during 2009–2016. Preliminary modelling using an analytical solution indicates that the observed surface subsidence rate at the ISRR site is consistent with the ground water depletion reported from Gandhinagar. An assessment of data from GPS sites at Lucknow and Varanasi in the Indo-Gangetic plains in Northern India does not indicate any significant subsidence at these sites which is also consistent with the in situ observations of insignificant depletion of ground water in the region. Introduction Land movement can occur due to processes other than that of tectonic origin. It is important to identify and characterise such processes so that ground movements due to tectonic causes can be estimated more accurately. This will help in assessing the seismic hazard in a more accurate manner. In some cases, the identification of such processes is quite easy when regions affected by such movement are known to be located at a distance from seismically active regions and from active faults. Other than the effects of seismic activity and volcan- ism, land elevation changes can occur due to: the effects of glacial isostatic adjustment; landslides; mining activi- ties; soil erosion; oil exploration and production; and the effects of groundwater abstraction. Ground uplift or sub- sidence in response to these processes can take place over a range of time-scales ranging from immediate impacts to impacts that may take place over time periods of decades to many centuries in the case of groundwater depletion and glacial isostatic adjustment (Argus et al. 2014). Slow mov- ing landslides can cause subsidence over several years to days (Malet et al. 2002). An ongoing drought in a region can cause uplift of the region on the scale of years (Borsa et al. 2014). Similarly, an excessive ground water withdrawal for irrigation and urban use can lead to ground subsidence on years to decades time scale (Lebbe 1995; Sun et al. 1999; Darini 2007; Teatini et al. 2006; Zhu et al. 2015). Seasonal variations in the hydrological load (in terms of precipitation) can also cause annual cyclic land movement (Fu and Frey- mueller 2012; Bettinelli et al. 2008). Similarly, the influence of flooding (Wahr et al. 2013) and cyclones (Milliner et al. 2018) can cause subsidence on short-term scale. With the advent of space-based techniques of monitor- ing land movement (e.g., GPS measurements and InSAR techniques) and hydrological load (GRACE), it is possible to assess and quantify the influence of these processes by meas- uring either the displacement or gravity change caused by these processes (Galloway et al. 2011). Evidence of deple- tion of ground water due to excessive ground water with- drawal for irrigation purpose in the Indian subcontinent has been reported quite extensively using GRACE data (Tiwari et al. 2009). Prominent among such regions are the Sindh, Punjab and Indo-Gangetic basins. In situ observations from ground water well data also indicate that groundwater depletion is taking place in the Indus, Sindh, Punjab, Indo-Gangetic and Bengal basins, and indicate increased abstraction from the Punjab and Sindh regions (MacDonanld et al. 2016). There could be several other localised regions facing excessive groundwater abstraction. The twin cities of Ahmedabad/Gandhinagar in * V. K. Gahalaut vkgahalaut@yahoo.com 1 Institute of Seismological Research, Raysan, Gandhinagar 382009, India 2 CSIR-National Geophysical Research Institute, Hyderabad 500007, India 3 National Center for Seismology, Ministry of Earth Sciences, New Delhi 110003, India 4 Department of Physics, Banaras Hindu University, Varanasi 221005, India