Estimation of Economic Risk from Coastal Natural Hazards in Louisiana

Louisiana, U.S.A., is among the most vulnerable areas globally to coastal natural hazards, with risk vulnerability likely increasing. The risks associated with non-tropical-cyclone hazards in Louisiana’s coastal zone have been understudied. This research enhances present and future (i.e., 2050) Louisiana risk assessment using locally-weighted, model-based hazard frequency/intensity and population projections. Results suggest that property risks associated with extreme cold temperature and tornado are and will remain costlier than those for hail and lightning. Property risks of extreme cold temperature and hail are projected to decrease with the expected warming temperatures, with those of all four of these hazards peaking in urban areas. Drought is and will remain a far greater risk to crops than these four hazards and extreme high temperatures, with perhaps 95 percent of the crop losses. Despite projected warming, extreme cold will remain a greater crop risk than extreme heat, though the latter often accompanies drought. Regarding present and future (i.e., 2050) Louisiana property risk to other non-severe-weather environmental hazards, wildfire risk peaks in west-central, east-central, extreme northwestern, and southwestern coastal Louisiana. Expansive soil risk peaks in southeastern and extreme southwestern Louisiana, and urban areas. Spatial patterns will remain similar for both hazards, but annual absolute and per capita losses are expected to increase substantially by 2050. The sinkhole risk is relatively small statewide, but property risk for some localized areas is substantial. To assess property risk from flood, ground-zero information collected at the individual building scale offers additional and likely improved building inventory attribute accuracy over existing information sources. A case study of Grand Isle, Louisiana, reveals that the 100-year xxi pluvial flood event today of almost 9-foot flood depths will increase by about 15 percent by 2050, causing a 20 percent increase in structure and content losses to approximately $203 million (2020$). A method is demonstrated to characterize the flood risk through the flood depth vs. return period relationship using the Gumbel distribution and spatial interpolation techniques, for areas of unknown flood depths. Collectively, these results will assist in allocating resources for mitigating and adapting to natural hazards in one of the most weather-hazard-vulnerable U.S. states