Identification of risk zone area of declining piezometric level in the urbanized regions around the City of Kolkata based on ground investigation and GIS techniques

Abstract

The falling piezometric level of groundwater is one of the major concerns, because of its immense importance especially in areas where treated surface water is not easily accessible. An attempt is made to identify the areas of maximum depletion of groundwater in KMC area by studying the post monsoon groundwater level data for the years 1991–2010. The Arc GIS software is used for the representation of the secondary data and also for the easy comparison of data. The study is done to find the groundwater trough in the region by predicting the groundwater level for post monsoon 2018 and validating the result with the data collected from the field. The result thus obtained is analysed with the help of the said software using the IDW (Inverse Distance weightage) technique. Thus, it is seen that GIS forms an excellent platform for the analysis of groundwater data and is very helpful in the present study. A comparative analysis has been made and it is seen that at maximum places in KMC region the water level is receding-places like Narendrapur, Chitpur, Sinthi, Ballygunge, Park Street, Jadavpur all show a receding trend, few places being exception like Mukundapur, Kalikapur where there has been a slight rise in the groundwater level, over the years. With the advancement in the surface water supply by the Kolkata Municipal Corporation and with the decrease in population density, there is no respite in the groundwater level recession in the city. Blessed with river Hooghly alongside, the potable water issue is solved to a greater extent but still the southern Kolkata shows dependence on groundwater. Due to the falling groundwater level the chances of land subsidence is seem to be high in the city.