River Response to Anthropogenic Modification: Channel Steepening and Gravel Front Fading in an Incising River

While most of the world's large rivers are heavily engineered, channel response to engineering measures on decadal century and several 100 km scales is scarcely documented. We investigate Lower Rhine River (Germany-Netherlands) measures, in terms slope bed surface grain size. Field data show domain-wide incision, primarily associated with extensive narrowing. Remarkably, has increased upstream end, which uncommon under degradational conditions. attribute observed two competing mechanisms: bedrock at boundary increases over part alluvial reach compensate for reduction net annual sediment mobility, narrowing reduces equilibrium slope. Another striking feature advance flattening gravel-sand transition, suggesting its gradual fading due an increasingly reduced difference between gravel sand reaches.