Abstract
The authors have been insisted that scaling property in Hokkaido region, which is the northern region in Japan, is almost simple scaling. Simple scaling is a scaling feature for regions where snowmelt-generated flood is dominant. On the other hand, multiscaling is a feature for regions where storm-generated flood is dominant.
In this paper, the authors tried to more rigorously investigate it than previous papers which the authors published. As a result, a likelihood ratio test indicated that a characteristic parameter which dominates properties of multiscaling is not zero in this region, viz., scaling in Hokkaido region exhibits multiscaling, In addition to this result, the authors investigated flood characteristics in Hokkaido region and concluded as follow: flood data in this region suggest belonging to multiscaling framework, but data exhibits ‘stronger’ simple scaling than other regions in Japan. According to this conclusion, the authors calculated each scaling exponent (which respectively corresponds to each return periods independently; say, 10yrs, 100yrs, 1000yrs....) which is the slope of equation for logarithm of catchment area and that of flood discharge. After that, the authors carried out inundation simulation, and obtained flood hazard maps in the Ishikari basin. The outline of making process of flood hazard map is as follows;
1)calculating flood discharge for return period T(yrs) for each gauged basins;
2)obtaining each scaling exponent for each return period; regional flood frequency analysis;
3)transferring flood discharge from gauged basins (observation station) to ungauged basins (location):
4)carrying out inundation simulation.
