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Discussion Paper # 27 Fluvial Geomorphology and Paleohydrology in Japan

An introduction to fluvial geomorphology and paleohydrology in Japan is provided for researchers who are unfamiliar with these topics. Studies by Japanese geomorphologists are reviewed including those published only in Japanese-language journals. Emphasis is placed upon the following aspects: 1) abundant sediment yields from steep watersheds subjected to frequent heavy rains despite heavily vegetated conditions, 2) extensive sedimentation in mountain piedmonts and coastal fluvial plains especially during the Holocene, 3) catastrophic hydro-geomorphological events associated with earthquakes and volcanic eruptions, and 4) the impacts of the increased heavy rainfall during the Pleistocene--Holocene transition on the post-glacial development of hillslopes and alluvial fans. These geomorphological characteristics differ from those in continental regions such as Europe and North America indicating that research on Japanese fluvial systems can contribute a great deal to understanding the global variety of fluvial geomorphology. Recent work on paleohydrological reconstruction in Japan is also reviewed.