Urbanization alters the geomorphological attributes of rivers by
increasing peak flows and reducing sediment inputs due to surface
sealing and efficient stormwater systems. Attribution of
geomorphological changes to urbanization has been mostly done using
purely statistical tools under a regional analysis framework, which does
not explicitly account for the hydrological processes by which
urbanization controls river morphology. Using a process-based hourly
hydrological model, we aimed to relate the observed geomorphological
changes in three French rivers to the historical urbanization of their
catchments over the period 1959-2018. Firstly, we applied the
hydrological model to generate an hourly streamflow time series from
climatic inputs by accounting for the changes in catchment
imperviousness, which we estimated from historical land-cover databases.
Secondly, we exploited the obtained streamflow time series to analyze
the temporal evolution of the flow competence, i.e. its ability to
transport sediments, with regard to the increased imperviousness of the
catchments. Results show that urbanization significantly increased flow
competence on the urbanized rivers, but the impact and its trend were
variable from one catchment to another. This demonstrates the role of
urbanization in increasing the channel instability that led to the
general incision and widening observed on these rivers over the past
three to four decades. Our approach shows promise in projecting the
impact of changing land-use and climate on channel geomorphology.