CHANGING GEOMORPHOLOGY OF THE KOSI RIVER SYSTEM IN THE INDIAN SUBCONTINENT
Nupur Bose, Department of Geography, A.N. College, Patna, India. nupur.bose@gmail.com
Ashok Kumar Ghosh, Dept. of Environment and Water Management, A.N.College, Patna, India, ashok.ghosh51@gmail.com
Ajay Govind Bhatt, Dept. of Environment and Water Management, A.N.College, Patna, India
The eastern state of Bihar in India is a flood-prone fluvial plain, with maximum havoc being caused by the Kosi river and its feeder channels. The recent floods of the Kosi basin by abrupt migration of the master stream eastwards by 110 kilometers have impacted upon the geography of this densely inhabited region. Migratory trends of the Kosi indicate that neotectonism and local isostatic adjustments are active in the heavily faulted river basin. Annual precipitation receipts also contribute to channel over –spillage, and current glacial recession due to global warming in the source regions of the Kosi impact upon the stream’s discharge. The channel has shown a marked affinity of following lineaments and faults. It now coincides with the Bhawanipur Fault, while an eastern branch of the river trends towards the Malda Fault. This study seeks to explain changes in the river’s morphology in the light of regional tectonic changes and changing climate in the subcontinent. The methodology adopted includes interpretation of satellite imageries, geological reports, flood reports and topographical maps followed by GIS analysis of the spatial shift of the Kosi river. This occurrence supports our earlier hypothesis that the ongoing changes in the surface water configurations, as evinced through remote sensing imageries within a span of twenty years, are due to active neotectonism and current climate change in the entire Kosi Fan Belt area. It is also indicative of heightened seismicity of northern Bihar Plains
