Analysis of the struck situation of coastal habitat in Matsukawa bay Wildlife Park by the tsunami disaster in Eastern Japan using time series satellite observation image

Background/Question/Methods

The earthquake and tsunami that occurred on March 11, 2011 affected the whole of Eastern Japan. Damage caused by the tsunami was extensive. Many environmental elements, such as tidal flats and pine forests, which were typically found on the coastal plain and in the Matsukawa Bay Wildlife Park that stretched from Miyagi Prefecture to Fukushima Prefecture, received the extensive damage from the tsunami. A time-series evaluation of the environmental changes to the coastal habitats in the coastal plain and to the Wildlife Park is now necessary to follow the future restoration of the natural environment. Many urgent investigations have been conducted using satellite observations following this tsunami disaster. Observation information from the Japanese ALOS satellite is especially searchable and provides broad and detailed data for the stricken region along the coastline. In the present study, satellite images were used to investigate the influence of the tsunami on the coastal habitat in the Matsukawa bay Wildlife Park in the northern part of Fukushima Prefecture and on the vegetation in the surrounding region, 12 days before, 3 days after, 8 days after and 21days after the tsunami struck. The change in characteristics of the natural environment caused by the wave strike was evaluated from these results.

Results/Conclusions

Much of the vegetation in the coastal habitat was eliminated by the tsunami, based on image classification analysis. The inland side of the Wildlife Park and the farmland surrounding the coastal habitat were extensively inundated with seawater. The seawater had a marked level of impurities from the surroundings in the tidal flat area, caused by the outflow of the soil from the inland areas, which confirmed the large range of the tsunami. The geographical features of the riverbed that flows in tidal flat were similar to those found before it was struck and appeared to have been almost restored from 8 to 21days after the tsunami struck, based on the images obtained after the impurities in the seawater of the tidal flat had decreased. Thus, some changed characteristics that will be pertinent to future environmental restoration were revealed by this time series investigation that was based on satellite observations of the vegetation distribution in the coastal habitat and the influence of the tidal flat on the bottom layer geographical features.