Flood hazard and risk assessment of 2014 floods in Kashmir Valley: a space-based multisensor approach

The combined effects of midlatitude westerlies lying in the lower troposphere over the Kashmir Valley and low-pressure systems originated from the Bay of Bengal and Saurashtra and Kutch regions caused torrential rainfall, which in turn produced devastating floods in the valley, during the first week of September 2014. The total actual flooded area was similar to 488.2 km(2) during September 10 to October 12, 2014. In this study, we utilized multispectral images of Landsat 8 Operational Land Imager (OLI) and Landsat 7 Enhanced Thematic Mapper Plus (ETM+) sensors along with the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) to derive the flood hazard and elements at risk. The linear combination of normalized flood depth, mean turbidity, and locational probability of flood parameters was taken to map the flood hazard. The flood risk, on the other hand, was computed as the product of flood hazard and vulnerability. Overall, the normalized difference vegetation index (NDVI) was reduced by similar to 50 % during postflood as compared with preflood image. Therefore, NDVI change in natural vegetation, cropped, and built-up areas was taken as proxy for vulnerability. Estimated land-use-specific hazard and risk mapping revealed that standing crops (rice and maize) were badly damaged in Bandipore, Baramula, Pulwama, and Bagdam Districts due to submergence and siltation by turbid flood water. Since natural vegetation stood above the flood level, it may have been affected least. Overall, Bandipore, Baramula, and Pulwama Districts showed relatively high flood hazard and risk to natural vegetation. Over the built-up area, Srinagar and Bagdam Districts were highly affected by turbid flood water. The estimated flood hazard and risk showed that Bandipore, Baramula, Bagdam, Pulwama, and Srinagar were the most severely affected districts in the valley.