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The 2011 Great East Japan Earthquake and Tsunami are one of the most catastrophic natural disasters that took place in Japan. The disaster caused widespread destruction to the estuarine and coastal areas along the northeastern region of Japan. The Abukuma River mouth, among many estuaries in Miyagi Prefecture, suffered major damage from the tsunami in which the sand spit and the sand terrace were severely eroded. The present study aims to provide a better comprehension of the morphology of the Abukuma River mouth within a decade after the 2011 tsunami based on the collected datasets of imagery and offshore bathymetry surveys. The consecutive changes of the sand terrace and sand spit indicate their connection influencing the morphological recovery in the Abukuma River mouth. About a year after the tsunami, the sand terrace re-appeared by a flood event and became the sediment source to recover the sand spit under the intrusion process. When the sand spit almost recovered and achieved a stable configuration, the sediment from the sand terrace into the river was restricted. As a result, more sediment from the sand terrace was expected to be transported to the downdrift area under the dominant wave condition in the Abukuma River mouth. [ABSTRACT FROM AUTHOR]

The 2011 Great East Japan Earthquake that occurred on March 11, 2011, had magnitude of 9.0 on the Richter Scale with the epicenter approximately 70 km east of the Oshika Peninsula in Miyagi Prefecture. This earthquake triggered terrible tsunami waves which hit the coast of Japan and propagated around the Pacific Ocean. The earthquake and tsunami caused extensive and severe infrastructural damage, such as damages of coastal protection structures and buildings, and significantly changed coastal and river morphology. This paper presents tsunami-induced coastal and estuarine morphology changes in Miyagi Prefecture, Japan, and subsequent recovery process in each study area. On sandy coasts, discontinuous coastal protection is likely to be severely damaged, resulting in serious erosion in the surrounding sandy coast. Furthermore, severe breaching was observed on sandy coasts where formerly river mouth was located, due to strong return flow from the catchment area. The restoration process of the coast and estuaries is highly dependent on sediment supply availability in the surrounding area. [ABSTRACT FROM AUTHOR]