Coastal topographical change around the great east japan earthquake (GEJE), tidal flooding area with inundation height estimated by the observation data, tidal flooding frequency with its height at the widespread coastal area by the numerical modeling of hydrodynamics were examined at the Iwate coast. At the target 4 fishing ports, the waterfront area below altitude 1m was increased by 4.5-12.1 times after the GEJE. Tide level between September 2013 to March 2014 fluctuated in the range of T.P. -1.16m and T.P. +0.89m. Assuming the raising of the land has not been made, the inundation heights were estimated 0.28-0.61m at a maximum. Numerical simulation calculated the maximum inundation height, the averaged flooding rate and the maximum flooding time at each fishing port. In addition, it was suggested that ground elevation and tide level studies in each local unit was important in order to estimate the flood risk.