We analyzed backscattering characteristics from TerraSAR-X data to observe changes occurring in agricultural fields damaged by a tsunami that was caused by the 2011 Tohoku earthquake. We used these data to extracted information about the drying process following flooding by this tsunami. Twenty time series datasets were computed, ranging from the day after the disaster to six months later. Flooded agricultural fields show lower backscattering coefficients than non-flooded areas. The results showed that some agricultural fields were flooded for more than three months. Backscattering coefficients are affected by incidence angle, yet temporal changes were clearly extracted from the backscattering coefficients of datasets with the same observation direction and incidence angle. The average difference between the mean backscattering coefficients of areas of agricultural field affected by the tsunami and those of areas not touched by the tsunami was seen to generally decrease with time.