Morphological Characteristics of River Mouths After the 2011 Tohoku Tsunami in Miyagi Prefecture
Coastlines and river mouths along the Tohoku Region in Japan are in the process of steady recovery following the 2011 Tsunami. The affected sandy coastlines and river mouths have undergone more significant changes than the corresponding cliffs, rocky beaches, and hard structures. Analyses of aerial photographs and topographic data related to pre-tsunami and post-tsunami conditions together with the estimated minimum width and positioning changes of river mouths describe how they have changed as well as the differences in their recovery processes. In many cases, there is an indication of stable recovery although the behavioral tendency differs, as in the case of the Natori and Naruse rivers. This study shows that the temporal topographic changes and the relationship with the tidal prism in the mouths of these river mouths differ, resulting in different sediment deposition and restoration processes. Sediment supply is intricately associated with the morphological changes in river mouth morphological changes, which in turn reflect on its recovery. The morphological changes in a river’s mouth present practical river management and maintenance problems in ports and harbors; consequently, continuous monitoring is essential.
KeywordsTohoku tsunami River morphology recovery Tidal prism
We sincerely thank Kitakamigawa-Karyu (Downstream region of Kitakami River) River Office in Tohoku Regional Bureau of Ministry of Land, Infrastructure, Transport and Tourism (MLIT) for the valuable topography data and aerial photographs used in this study. We are also grateful for financial support in the form of a Grant-in-Aid for Scientific Research from JSPS (No. 2301367) and the River Environmental Fund (REF) from the Foundation of River and Watershed Environmental Management (FOREM). The first author is a JSPS Postdoctoral Fellow (No. 25-03364).
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