Flood hazard in a basin depends upon the hydrological response of the upstream basin area. The upstream basin area may produce different amounts of run-off for a given rainfall based on its hydrologic response. The present communication shows the importance of drainage network characteristics in understanding the hydrologic response of a basin. The study is carried out through Geomorphic Instantaneous Unit Hydrograph analysis, wherein Horton's morphometric ratios were used to define the drainage network. A floodprone river basin in north Bihar plains has been selected as a study area.

Flood hazard is one of the most severe problems in the Himalayan river basins. Although floods are essentially hydrological phenomenon, the uneven distribution of floods in the river basin highlights the control of geomorphological and geological factors. A proper understanding of these factors is critical for a successful flood management programme. Remote sensing data is of immense value in evaluating the geomorphological and geological controls in flooding. The present paper highlights the control of geomorphology and neotectonics on flood hazard in north Bihar Plains, eastern India.

The Indo-Gangetic plains are drained by several fan and interfan rivers fringing the margin of the outer Himalaya. These fan and interfan river systems are distinctly different from each other in terms of hydrology and sediment transport and generate typical

The Himalayan arc, 40% of which ruptured in the last two centuries, has witnessed half a dozen large to great earthquakes including the 1833 and 1934 Bihar