FLOOD AND TSUNAMI FLOW IN RELATI
FLOOD AND TSUNAMI FLOW IN RELATION TO THE
LANDFORMS OF COASTAL AND ALLUVIAL LOWLANDS
Masatomo UMITSU
Department of Geography, Graduate School of Environmental Studies,
Nagoya University, Japan
Abstract
Flood control is a very important issue of the environmental
management in the alluvial and coastal plains. For the detail management, it is
necessary to know the behavior of the flooding on the plains.
Micro landforms of these plains are closely related to the
flow and inundation depth of floods. Landforms of an alluvial plain are roughly
classified into three units: alluvial fan, floodplain and delta. Landforms of
these units are further classified into micro landforms as natural levee, flood
basin, paleo-river channel, beach ridges and so on. The places on higher micro
landforms are generally flood free places or the places where the flood depth is
shallow. On the contrary, flood water concentrate on the place of the lower
micro-landforms as flood basin or back swamp and inundation depth is deep in the
areas. Coastal areas as coastal plain or delta plain are subjected to the
inundation by tidal surge or tsunami. Regional differences of the landforms of
the coastal plain are also related to the difference of flood condition in a
plain.
Hazard map or risk map for the flood disasters should be
taken the characteristics of micro landforms into consideration.
Key words: Flood, Tsunami, Coastal plain,
Alluvial plain, Landforms
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