Development of natural disaster risk map as reflected in flood, wind and snow in Ulsan City

In this study, grid-based flood inundation map, wind velocity map and snow load map were developed to calculate reasonable natural disaster insurance rate as one of the non-structural measures in Ulsan city, Korea. Flood inundation map based on 100-year flood shows that the maximum water depth was 12.04 m with 2.5% (26.44 km(2)) of Ulsan city area (1057.50 km(2)) inundated. In mapping wind velocity and snow load based on 100-year frequency return period, the wind velocity and snow load showed values ranging from 23.8 to 47.4 m/s and 0.44 to 0.54 kN/m(2), respectively. Based on the flood inundation map, the flood risk map was developed and 4 risk levels were determined: safe, warning, dangerous and severely dangerous water depth, which represents the degree of damage against lives and buildings inflicted by flood. The wind risk map and snow risk map made the same specified classifications for areas lower than the design wind velocity and snow load of the city. The flood risk map, wind risk map and snow risk map were applied with the proportionate damages from flood, wind and snow of Ulsan city for the last 10 years to develop the integrated natural disaster risk map. Each risk map and integrated natural disaster risk map developed by the study are assumed to be useful to build structural measures for disaster prevention such as prioritizing disaster prevention structures and determining where set them up in the future as well as non-structural prevention measures like reasonably natural disaster insurance against natural disasters and creating natural disaster evacuation map.