In order to examine the effects of sediment supply on wave-ripple morphology, we conducted flume experiments under similar hydraulic conditions with three different sediment supply rates. In a case with relatively low sediment supply rate, the wave-ripple morphology was maintained. As the sediment supply rates increased, the initial wave ripples flattened over a larger area. Under the hydraulic conditions and sediment grain size in the present experiments (water depth: 0.3 m, wave period: 1.0 s, wave height: 76-78 mm and sediment grain size: 0.20 mm), flattening of wave ripples was observed at bed aggradation rate of 32 mm/min. This result suggests that the previous formation models of wave-ripple lamination, in which wave ripples are unaffected by sediment supply, do not necessarily hold when the sediment supply rate is high.

Distribution of clastic grains transported and deposited on high water bed during Typhoon Hagibis (T1919) flood in the middle reaches of the Tama River was investigated. Gravel deposition tends to be predominant from upstream part to river channel side of central part of banks. On the other hand, middle-fine grained sand deposition tends to be predominant from far side from river channel of central part to downstream part of banks. The sands often make low-relief 2D dune bedform. The gravels were often deposited on a trough which has been fixed on a bank during several decades. Average rate of the gravel movement during T1919 flood on a trough was estimated as being less than several 10 m/hour. Even though the T1919 flood, one of the biggest flood during several decades in Japan, transported and arranged various sized grains (boulder-sand) on sand-gravel bank conspicuously, hardly changed the form of the banks. Considering devastating flood caused by the rainfall beyond an expected level might increase in future, it is important to record and publish the situation of transport and sedimentation of the clastic grains by T1919 flood at various place in the Japanese islands.

Results of observation on the flood crevasse channel deposits at the Mizusijinjya-higashi archaeological site in Joyo City, Kyoto, Japan, we found the followings that the sand layer of channel sediments and the mud layer of floodplain sediments form a set of contemporaneous heterotopic relatioship with a thickness of several tens of centimeters, and the units overlap to form an aggregate of valley-shaped channel deposits. That is, one contemporaneous heterotopic unit was deposited during one flood period of a few hours to a few days, and the unit was also formed by reflecting the difference in concentratio of the substance in flow. It is difficult to identify lithological boundaries in such deposits, and their traces are prone to error.