THE EFFECTS OF GCMs AND SPATIAL RESOLUTION IN THE ESTIMATION OF THE FLOOD DAMAGE CAUSED BY CLIMATE CHANGE

In the estimation of flood damage over the whole of Japan using a two-dimensional unsteady flow model, we compared the difference between the fluctuation of the damage cost when using multiple GCMs and the using different spatial resolutions. The standard deviation of the damage amount was estimated to be 50.7 billion yen in the 2050 RCP 2.6 scenario and 68.0 billion yen in the 2050 RCP 8.5 scenario for 6 different GCMs. The ratio of this standard deviation to the annual expected damage is 3.56% and 4.70%, respectively. On the other hand, when the spatial resolution was changed from 1 km to 250 m, the annual expected damage decreased by 223.9 billion yen. The ratio of this difference to the annual expected damage is 13.9% at 1km resolution and 16.1% at 250m resolution. It was suggested that the effect of spatial resolution should be more important than the uncertainty of GCM for the estimation of damage cost.