Attachments
Executive Summary
Flood hazard maps are one of the very important non-structural methods of flood damage mitigation. These maps are useful in planning developmental activities, construction of relief, rescue, health centers and in planning flood tolerant crops in floodplains. Satellites provide synoptic observations of the natural disasters at regular intervals that help in disaster risk reduction in the country. Over a period of time, National Remote Sensing Centre, ISRO has created a repository of large data pertaining to the floods & cyclones in different areas of the Country. These historical flood maps, generated by NRSC/ISRO, are useful for identification of flood hazard areas. First version of Bihar Flood Hazard Atlas was released in 2013, in which historic satellite data of 1998 to 2010 was used. On behest of National Disaster Management Authority, NRSC/ISRO has revised and updated State level and District wise Flood Hazard Zonation Atlas for Bihar State using the available historical satellite datasets spanning over 22 years (1998 to 2019). About 274 Indian Remote Sensing (IRS) satellite and foreign satellite datasets (optical and microwave) during this period were acquired covering different flood magnitudes in Bihar State and used in generating the flood hazard maps. The flood hazard zones are categorized into five classes ranging from very low hazard zone to very high hazard zone based on the hazard classification schema finalized by the expert committee constituted by NDMA. Water level data of 40 gauge stations for the 22 years period has been obtained from Central Water Commission and analyzed to compute number of flood events in each year. Flood hazard index was calculated for each district considering the flood hazard category, hazard area and intra annual flood variations to find the severity of flood hazard in all districts. Flood inundation and frequency of occurrence are provided in the Atlas. The flood hazard maps have been validated in ground by the Disaster Management Department, Government of Bihar, through its district administration. Suggestions given by them are incorporated in this report. In Bihar State, it is estimated that about 35.06 lakh hectares of land is affected by floods during the last 22 years and 29 districts come under very high, high and moderate flood hazard category. It is believed that this atlas would be found to be useful in its value for followup flood mitigation efforts in the Bihar State.