Design with nature: Causation and avoidance of catastrophic flooding, Myanmar

Myanmar is among 15 nations that account for 80% of global population exposed to flooding. In 2008, the country suffered exceptional damage and human mortalities (>138,000) from tropical storm Nargis, which followed an unusual but not unprecedented storm track. In 2015, heavy monsoonal rains related to the tropical Madden–Julian Oscillation plus a slow-moving tropical storm (Komen) together caused major flooding, ~130 fatalities, and very severe damage and losses. Both events triggered international food, medical, and other assistance, including efforts to design rebuilding with greater resilience to floods. Orbital remote sensing can be employed to characterize such damaging floods and quantify future flood risk; advanced lead-time flood prediction is also increasingly accurate and available. These capabilities must, however, be applied in a context of environmental variables (climate, sea level, dams, and land cover) that are changing the hazard. In addition to the hydrometeorology, distal causes for flood disasters include: high sediment loads carried by Myanmar rivers, locally rapid rates (>50–100m/y) of channel migration, expansion of population into vulnerable locations, and anthropogenic modifications to floodplains, watersheds, and the coastal zone. Engineering projects can protect local communities, but flood control structures will fail again unless the environmental changes that increase exposure to flood damage are also mitigated. Earth Science-based methods for long term reduction of societal exposure include floodplain reconnection, levee removal, controlled avulsions, and redirecting new housing and other economic development onto lands with less severe flood risk.