The 1934 flood disaster and geomorphological changes in the upper Tedori River, Japan

Abstract

The large flood disaster occurred in 1934 in the Tedori river basin. This paper discusses the geomorphic processes of valley-fill caused by many landslides and downcutting after the event in the upper Tedori river basin. The thicknesses of the vally-fill deposits were estimated at 40-70m. Four levels of terraces which were formed by downcutting after the event are distributed in this area. Using aerial photo interpretation and DBH of the pioneer plants, the ages of terracing were estimated. Although immediately after the event the channel form is braided, about 20 years after the event the channels were fixed. The rate of the downcutting is getting slow exponentially.