River Systems of West Bengal: Water Quality and Environment

Numerous rivers flow across the state of West Bengal forming a river network with the tributaries and distributaries of these rivers across the state. The principal river basins in the state are Ganga, Brahmaputra, and Subarnarekha which form a number of subbasins in the land of Bengal. Rivers in majority change their courses in all directions and such shifting of river courses cause the changing scenario of the direction of flow with space and time. Interbasin transfer of river water helps in irrigation and flood control and was introduced in the state of West Bengal in the British era. River commons happen to be a social contract which is closely related with the common properties’ resources of the riverside people. Among these rivers, which have water throughout the year, problems like water pollution are relatively less. During the dry season, pollution levels are high for factories or municipalities located along rivers with knee-dip water. Recently, thirteen river stretches in West Bengal have reached such levels of water pollution that they are not even suitable for outdoor bathing. Using the physicochemical parameters obtained from these stretches of the rivers, water quality indices were computed and after that the water quality rating was determined. From the obtained values of water quality rating, it is observed that the water quality of most of the river stretches in West Bengal is quite poor and often below the permissible limit.