Impact of urbanization and scanty rainfall on groundwater resources : A case of Madurai city

The comprehensive understanding of the impacts of urbanization in the rapidly urbanizing cities is of paramount importance in the era of climate change. This research documented the impacts and challenges faced in the comprehensive management of surface water and groundwater resources, using the combination of remote sensing (RS) data, observed data and survey data. To increase understanding-of the regional hydrology, this study, for the first time, used 28 well data and recorded the fluctuations-in depth to water level from 2003 to 2018 in Madurai- West using RS and GIS. Results indicated the-deficiency in annual rainfall percentage departure for 11 years between 2002 to 2017. The depth of tube-well and bore well to extract this groundwater resources was found increasing at an alarming rate from 8 meter on an average in 1990s to 200 meter in 2017-18. Using areal imagery, a rapid increase in urban area, up to 300%, was estimated between 2002 and 2018 in peri-urban and urban Madurai. Field survey and groundwater data also indicated that, in the past 15 years, approximately 60% of the groundwater levels have gone from safe to critical status (i.e. extraction rate above natural recharge rate), leading to unsustainable groundwater levels. As a result of erratic rainfall patterns and increased urbanization, the discharge into the tank cascade system decreased, which lead to a decrease in the natural recharge of-groundwater in the areas adjoining the tanks. Moreover, the surface runoff was found as high as 86% of-the rainfall in urban and peri-urban areas. The study concludes with documenting the overall importance of tank cascades to create awareness towards changing climate patterns and anthropogenic activities, which can limit its efficiency.