Anthropogenic impacts on aggrevating fluvial hazards: a Case of nagavali river basin, india

In 2000, the Government of India announced plans of eight hydro-power projects along the Nagavali river, one of the East-Indian River flows through Odisha and Andhra Pradesh before entering the Bay of Bengal. Of these, three projects have been implemented which is significantly altering the river’s dynamics. This study evaluates anthropogenic impacts on fluvial processes of these sites, with particular emphasis on river avulsion, channel incision, and reservoir-induced geomorphic change. For detecting such changes, Google Earth Images of different time periods have been used and hydrological, meteorological, geologic-geomorphic, and lithological data were collected and analysed from different Govt. sources as well as from the detailed field study. At the Hathipahar Waterfall site, dam construction triggered a rapid avulsion, resulting in a westward channel shift of approximately 550 m, channel incision of ~45 m, and land loss of about 0.54 km2 during a single flash-flood event, indicating severe geomorphic instability. At the Thotapalli Regulator, post-construction flood events caused substantial upstream channel widening (from ~500 m to ~1200 m) and reservoir expansion from 1.39 km2 to 9.91 km2 within nine years, reflecting strong backwater effects and sediment redistribution.