Rainfall variability and Spatio temporal dynamics of flood inundation during the 18th August 2008 Kosi Flood in Bihar, India (original) (raw)

The devastating flood in Kosi River initiated on 18 August 2008 resulted in heavy loss of human life and natural resources in the Bihar state of India. About 2.5 millions people become homeless and 2516 km 2 of agricultural land including fallow land is damaged by the flood inundation. The spatio-temporal dynamics of flood inundation during a period of two months from 20 August to 21 October 2008 has been carried out. The temporal satellite images of RADARSAT were used to map the spatial-inundation pattern of Kosi flood whereas, IRS P6 LISS III optical satellite data of October 2004 was used to map the land use characteristics of the region in a non flood situation to evaluate the loss of agricultural land inundated by Kosi flood. Rainfall variability in the entire Kosi river catchment was assessed by comparing the monthly rainfall during monsoon season for a period of 1998-2009. The variability in rainfall pattern during the pre and post Kosi flood event was examined to develop insight into genetic aspect of flooding. The study revealed a loss of 2135 km 2 of standing crops due to highest flood inundation of 3089 km 2 as on 5 September, 2008. Rainfall pattern indicates much higher rainfall in the lower Kosi catchment which probably induced the conditions causing breach of embankment and resulted in the initiation of Kosi flood on 18 August 2008.