Application of habitat modification score and fluvial functioning index in discussion of eco-hydrological behavior and flood risk zonation of Himalayan foothill rivers, West Bengal, India

The changes in the river stretch by engineering constructions such as bridges affect its physical attributes and imply an impact on biological functioning. Thus, the ecological behavior of the river devises a scope for the future study correlating the probable flood risk areas. The alteration of river habitat and the riparian environment have been investigated in the present study using two methods: Habitat Modification Score and Fluvial Functioning Index. The results have further considered scouting with the risk zonation map that signifies the sensitive affected zone during the high discharge phase. The study displays the impact of human intervention that shows a better river habitat condition and healthy riparian environment. It is distinctly noted along the studied reach that, the bridge construction has modified the river channel showing poor functioning level and habitat condition. The flood risk-zoning map too highlights the areas with human interventions that are likely to get affected by high flood occurrences than the least intervened zones. Hence, the study offers an insight into the bridge constructions' ascendancy on the river habitat condition and flood risk zone.