ASSESSING SOCIOECONOMIC IMPACTS OF SEA LEVEL RISE ON JAPANESE COASTS VIA SCENARIOS OF POPULATION AND LAND USE

Abstract

 This study evaluated the impact of sea level rise (SLR) and astronomical tides in coastal Japanese prefectures, and assessed outcomes such as the potentially inundated area, affected population, and economic damage. The latest climate scenarios, tidal data, and shared socioeconomic pathways (SSPs) were used to evaluate SLR and inundation effects in the coastal areas of Japan at a resolution of 1 km. Economic assessment was incorporated by including SSP population and land use scenarios, also gridded at 1 km. This study evaluated economic damage based on the “Manual for economic evaluation of flood control investment (draft), ” whereas our previous study used the econometric relationship between past hydrological disasters. The uncertainty between high and low emission scenarios (SSP5-8.5 and SSP1-2.6) was also analysed. The potentially inundated area of Japan was determined to be about 2,111-2,127 km² in 2050 and 2,261-2,598 km² in 2100. The affected population was estimated to be 4.45-4.70 million in 2050 and 3.76-4.92 million in 2100, depending on the SSP. Finally, the economic damage was estimated to vary within about 143-170 trillion yen in 2050 and about 229-430 trillion yen in 2100. All impacts (inundated area, affected population, and economic damage) under SSP1-2.6 were smaller than those under SSP5-8.5, suggesting the importance of mitigation efforts. Economic damage using this “manual” estimation method was more than 20 times as large as when using the previous estimation method. The manual method also indicated more impacts around three major bays, mainly due to damage to buildings and the size of the affected population.