River Stabilisation by Breach-ramps and Widening

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.

River Stabilisation by Breach-ramps and Widening

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 o...