Narayan Chandra JANA, The University of Burdwan, India
Flood is undoubtedly a significant natural hazard since the geological past and also to every major civilization throughout the globe, as all major civilizations are mainly flourished in and around different river valleys. As flood is the most devastating hazard for the riparian people, we have developed numerous flood protection measures including the construction of reservoirs, dams, embankments, etc. All these activities may reduce the impact of flood to some extent but we couldn’t ignore the fact that flood is a natural phenomenon and common hazard in almost all river systems irrespective of protection measures. Keeping the fact in mind it is very essential to study the behavior of the river channel during flood events. Interestingly the river channels behave differently in bedrock system and alluvial system. Bedrock River systems respond with high stream power and shear stress with low duration flood whereas the alluvial systems respond with low to moderate stream power and shear stress with long duration flood. The Lower Damodar River Basin (area»24,235 km2 with 541 km long course) is located in West Bengal, India where the effect of large to moderate magnitude floods are too pronounced during the pre-dam (1933-1956) and post-dam (1959-2007) periods. Some of the largest floods since 20th century were recorded during 1913, 1935, 1941, 1958, 1959, 1978, 1995, 2000, 2006, 2007 and 2015.
The present study shows that the infrequent large magnitude floods influence channel form, move large volumes of sediment, and leave strong imprints on channel morphology in alluvial river system like Damodar. The main objectives are to quantify the potential of all effective monsoon flows in terms of specific stream power, duration and energy expenditure as well as to assess the different channel response in terms of width-depth ratio and generation of shear-stress for Damodar River in India.
Mots clés : Flood|magnitude|response|bedrock|alluvial
A103876NJ