Flood Hazard Zonation Atlas for Odisha

• Odisha has come out with a unique flood hazard atlas on the basis of historic flood inundation captured through satellite imagery over the period from 2001 to 2018.
• It is expected to help the State manage floods more efficiently.

Flood Hazard Zonation Atlas

• The National Remote Sensing Centre (NRSC) of the ISRO had taken the study on flood hazard Zonation for Odisha.
• A large number of satellite images acquired over 18 years (2001-2018) were used. All satellite data sets were analysed and flood layers were extracted.
• All the flood layers corresponding to a year are combined as one inundation layer, so that this layer represents the maximum flooded area in one year.
• The NRSC analysis says about 8.96% (13.96 lakh hectares) of land in Odisha was affected by floods during 2001-2018. Out of total flood-affected area (13.96 lakh hectares), about 2.81 lakh hectares of land falls under high (inundated seven-nine times) to very high (inundated 10-14 times) flood hazard categories.
• Eight out of 30 districts such as Bhadrak, Kendrapara, Jagatsinghapur, Balasore, Puri, Jajpur, Khordha and Cuttack districts are more flood-affected districts.
• As high as 77% of Bhadrak and 70% of the Kendrapara district have been categorised as flood hazard.

Why Odisha?

• Vast areas of the State are inundated when there is flooding every year in major rivers, namely, the Mahanadi, Brahmani, Baitarani, Subarnarekha and Rushikulya.
• Some of the rivers like, the Vamsadhara and Budhabalanga, also cause flash floods due to instant run-off from their hilly catchments.
• Damages due to floods are caused mainly by the Mahanadi, the Brahmani and the Baitarani, which have a common delta where floodwaters intermingle, and, when in spate simultaneously, wreak considerable havoc.
• The entire coastal belt is prone to storm surges, which is usually accompanied by heavy rainfall, thus making the estuary region vulnerable to both storm surges and river flooding.

A useful resource

• All such combined flood layers for 18 years were integrated into flood hazard layer representing the observed flood-inundated areas with different frequencies.
• This layer was integrated with the digital database layers of Odisha.
• The atlas would serve as a useful resource of information for policy makers, planners and civil society groups.