Human impact on fluvial systems in Europe with special regard to today’s river restorations

Climate, geology, geomorphology, soil, vegetation, geomorphology, hydrology, and human impact affect river–floodplain systems, especially their sediment load and channel morphology. Since the beginning of the Holocene, human activity is present at different scales from the catchment to the channel and has had an increasing influence on fluvial systems. Today, many river–floodplain systems are transformed in course of river restorations to “natural” hydrodynamic and morphodynamic conditions without human impacts. Information is missing for the historical or rather “natural” as well as for the present-day situation. Changes of the “natural” sediment fluxes in the last centuries result in changes of the fluvial morphology. The success of river restorations depends on substantial knowledge about historical as well as present-day fluvial morphodynamics. Therefore, it is necessary to analyze the consequences of historical impacts on fluvial morphodynamics and additionally the future implications of present-day human impacts in course of river restorations. The objective of this review is to summarize catchment impacts and river channel impacts since the beginning of the Holocene in Europe on the fluvial morphodynamics, to critically investigate their consequences on the environment, and to evaluate the possibility to return to a “natural” morphological river state.