The funnel-shaped study area with 647.7 km2 of areal coverage, is situated in the Darjeeling DistrictDarjeeling district with a small portion of the Jalpaiguri District also. Since this hill-plane interface region is the gateway to the northeastern states of India and situated adjacent to three neighbouring countries, i.e. Bangladesh, Nepal and Bhutan; immense development in terms of transportation can be notable. This chapter gives detailed descriptions of various aspects of the study that is the Mahananda system. All the physical aspects such as geology, climatic parameters, geomorphology, drainage texture, vegetation cover and soil, and the human aspects such as population pressure and the landuse landcover scenario have been mapped. It is understood that the sub-Himalayan foothill region of West Bengal is getting urbanized at a rapid pace, immensely affecting natural resource management. It is understood that the hilly region and the floodplainsUrbanized floodplain are separately analysed in this study since the geoenvironmental conditions are entirely different.