Risk of extreme events in delta environment: A case study of the Mahanadi delta.

Anthropogenic climate change is considered as one of the greatest environmental, social and economic threats to the future world. Low lying deltas all over the world are increasingly subjected to multidimensional risk of sea level rise, cyclone, surges and salinisation. The life and livelihood of the communities of such deltas are endangered due to climate change acting as risk multiplier. The Mahanadi delta in the state of Odisha, India is one of the such populous deltas with estimated 8 million population in 2011 with a density of 613 persons/km. Over the past decades, it experienced major climatic threats in the form of cyclone, surge inundation and flooding with variable intensities and impacts along and across the coast. The present research assessed the risk of climatic extreme events and their variability in the delta, with an intention of mitigation or adaptation to possible impacts in specific region. Synthetic Aperture Radar (SAR) data and daily rainfall data were used to extract flood inundation. Tropical Cyclone Risk Model (TCRM) along with surge decay function was used to estimate cyclonic wind speed and surge inundation and risk indices were computed using fuzzy logic based approach. The result shows that in the coastal districts, risk of severe cyclones rank above the heavy floods. Agriculture, the main livelihood of these districts (71%) is impacted adversely making the delta community vulnerable to such extreme events. Kendrapara followed by Bhadrak and Jagasinghpur districts appear to be most risk prone segment in the delta making the northern part comparatively more risk prone where focused mitigation and adaptation actions are needed.