Assessment of Health of River Ganga at Varanasi, India

Abstract

World across, there is an increasing concern about river health. In India, Ganga River Basin Management Plan (GRBMP) 2015 considered River Ganga as an ecological entity. This paper attempts to present a framework for river health assessment in India and discusses its applicability for River Ganga near Varanasi. In the proposed framework, the River Health Condition (RHC) is assessed through the calculation of River Health Index (RHI) on a 0-100 scale and categorized as Acceptable or Poor. RHI is calculated by using selected parameters/indices normalized on the 0-5 scale based on their critical and target values. River Health is presented through a coloured circumscribed pentagon each of whose side represents one of five indicator groups: i. Organo-electrolytic-bacterial qualities. ii. Nutrients, iii. Algae, iv. Macroinvertebrates, and v. Fish. Application of the proposed framework has been tested and explained using observed data for four seasons per year for two years from five locations of River Ganga near Varanasi. The colour of circumscribing pentagon reflects overall river health condition at a given location and each side of pentagon reflects health score concerningto one indicator group. The analyses indicate that the health of River Ganga near Varanasi is improving with time. The river health is found at its best level during Spring season and unstable during Post Monsoon period at most of the locations. The severely reduced RHI indicate “Overstressed” condition of River Ganga at the confluence points of River Assi and Varuna, which are evidenced by the presence of pollution tolerant biotic species. There are clear stretches of the river near outfall points which are nutrients rich and organically polluted causing poor health of river showing a disturbed balance of biotic species. Indicator group score based RHI gives a clear identification of critical parameters which may be used in strategic planning for river health restoration.

Keywords

• river health index, river health condition, river health assessment, biotic indicators, river ganga