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Using aerial photographs and field measurements, sandy overbank deposits formed by the large-magnitude floods of 1993/94 and 1995 were quantified along two branches of the Dutch Rhine river system: the Waal (1993/94 and and the IJssel (1995). These deposits were laid down intermittently all along the length of these rivers on the top and landward slope of the natural levees, and covered about 4 per cent of the embanked floodplain on the Waal and about 1 per cent on the IJssel. The overbanks and transport mechanism is basically convective by nature. The spatial variability of overbank sedimentation points to the important role played by helicoidal currents in determining overbank deposition.The presence of embankments and training works appears to influence the sand transport to and morphological development of the floodplains along the Dutch Rhine river system. Overbank deposition volumes about equal present estimates of sand transport during a large-magnitude flood. It appears that studies on sand transport in the Dutch Rhine carried out so far underestimate sand transport during floods.

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For the purpose of restoration, a process-based geomorphological and ecological classification of rivers and river reaches has been developed to help identify both past and present-day geomorphological processes along lower branches of the Rhine. Historical maps are used to analyse floodplain development since 1600. The series of maps shows development and erosion of bars and floodplains, and land use reflects both vegetation and geomorphological patterns and indicates that the ecological succession was strongly related to geomorphology. Historical measurements (early 19th century) of the water depth and water levels are used to derive historical river profiles and water duration curves. Present-day hydraulic parameters were calculated which show that they are not related to the geomorphological patterns in floodplains. Changes in the geomorphological activity of the river are strongly related to changes of the width-depth ratio of the main channel. Potentials for bar and levee development are therefore based on differences between the width-depth ratio of the Rhine branches.

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