Dam-induced changes in flood hydrology and flood frequency of tropical river: a study in Damodar River of West Bengal, India

摘要

The Damodar River of West Bengal is popularized as 'Sorrow of Bengal' due to massive unpredictable destruction in the monsoonal floods, recorded since 1665. After establishment of Damodar Valley Corporation (DVC) of India in 1948, Tilaiya, Tenughat, Konar, Maithon and Panchet dams (Jharkhand) and Durgapur barrage (West Bengal) are built to regulate flood flow to a certain limit. But, as the floods were unpredictable in pre-dam phase, even now, lower Damodar Basin is not secure from the monsoonal floods. To assess the flood risk and nature of flood discharge, we have focused here to fit extreme value distribution (EVD) to the annual peak flow of the Damodar River using mainly Gumbel and log Pearson type III distributions. Pre-dam (1934-1957) and post-dam (1958-2007) flood frequency analysis has significantly projected maximum probable flood discharge of Damodar at Rhondia with a certain return period of occurrence, and it provides an idea about future flood risk in lower Damodar Basin.