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Numerous gravel-bed rivers are affected by unceasing degradation problems,mostly caused or in- creased by technical measures upstream.In Germany removing the bank fixations is regarded as a concept to dissolve the problem.By allowing lateral erosion and in consequence river widening the bed load transport ca- pacity will be decreased.Additionally the eroded bank material will serve as additional sediment influx. Nevertheless in some cases additional measures are required for a sustainable stabilization of the river bed.Since several years ramps consisting of boulders are used for a reduce of the slope.Despite some ecologi- cal and esthetical advantages they cannot accomplish all requirements related to a migration of fishes and organ- isms.Ramps having a breach in their centre offer better conditions concerning the migration and the sediment transport.Actually they are under theoretical and experimental investigation for a project in Germany.This pa- per illustrates exemplarily some results of the preliminary investigations about breach ramps as well as results of the large scale tests on river widening.
Numerous gravel-bed rivers are affected by unceasing degradation problems, mostly caused or in- creased by technical measures upstream. Germany removing the bank fixations is regarded as a concept to dissolve the problem. By permit lateral erosion and in consequence river widening the bed Adhering the eroded bank material will serve as additional sediment influx. Nevertheless in the cases stabilized by the river bed.Since several years ramps consisting of boulders are used for a reduce of the slope. Idepite some ecologi- cal and esthetical advantages they can not accomplish all requirements related to a migration of fishes and organ- isms.Ramps having a breach in their center offer better conditions concerning the migration and the sediment transport. Actually they are under theoretical and experimental investigation for a project in Germany. This pa- per illustrates exemplarily some re sults of the preliminary investigations about breach ramps as well as results of the large scale tests on river widening.