| Field observations were performed on Mukawa Bridge located 2.5km upstream of the mouth of the Mukawa River，Japan during the 1998 snowmelt flood．Observations were made of water level discharge，bed material and various components of water quality．As a result of analyzing water-quality components，it became clear that the water-quality components，which increase in comcentration at the time of floods，are primarily the undissolved elements．These elements are particulste nutrients and have a vere high correlation with suspended solids．The nutrients are adsorbed to suspended solids and transport in rivers during floods．By investigating the nutrition salt included in the sediments on flood plains and suspended solids，the concentration of the particulate nutrients at the time of floods can be estimated by investigating the sediments on the flood plains．Thus，it is very important to grasp the behavior of suspended solids durring floods when the water quality and river environments are of practical interests．The suspended solid in transported toward the center from the shore in an early stage with water level rising and agterward it moves to the shore from the center．The rise in concentration of undisolved solids during flood was due to the deposition of undisolved solids on the flood plains and near the bank． |
