Since the conventional wave refraction theory for surface water waves is based on geo-optic approximation, it fails to predict wave height at and near a caustic where ray crossings occur. This report shows that this difficulty of the geo-optic theory can be overcome by application of our nemerical analysis method developed for wave propagation in the region of arbitrary shape of the constant water depth in the former report.
　In this report, the numerical analysis method is applied to wave propagation on a circular shoal where a caustic is formed and hydraulic model experiments are made for same situation. By comparing both results, the validity of our method is confirmed. This method of numerical analysis may be applied to ihe calculation of
wave height distribution in the region of more realistic bottom topography.