Venturing deep into high right-bank slide of river Ganges near Chandernagore Strand, in Hooghly, India

Abstract

Two multi-storied occupied apartment buildings and a clinic of ‘ Red-Cross Society’ in Chandernagore-a former French colony, located very close to the banks of tidal river ‘ Hooghly’ (-the southernmost part of River Ganges- the major hydrodynamic system that formed the world's largest delta) are standing precariously, following some recurrent slides of high river-bank during the last year’s monsoons. The area where the ground caved in, is on the end of the famous Strand Bank Road (in Hooghly district of West Bengal in India); which is supposed to be the best decorated bank of the river ‘ Ganges’ along its entire length of 2500 km. The opposite river bank is an official sand mining site. The river over considerable stretch at both upstream and downstream apparently seemed stable when analyzed over an extensive temporal domain from old Survey of India toposheets, recent satellite imagery, digital elevation model, field hydrographical survey synthesized in Geographical Information System (GIS) platform. A closer look into the geotechnical aspects supported by subsurface exploration, post failure on-site exposures and stability analysis revealed certain startling facts when considered in association with the hydro-meteorological factors and fluvial dynamics. An in-depth study of the factors responsible for the localized erosion is presented based on site observations and evidences, analyzed in association with real time hydrological and meteorological data.