Sensitivity of West and Central European river systems to environmental changes during the Holocene: A review

Abstract

Sediment deposition in floodplains is an essential part of the sediment dynamics of a catchment. These sediment dynamics can vary largely on a Holocene time scale under the influence of driving forces such as land use and climatic variations. In this paper we review the Holocene floodplain sediment deposition history of rivers in West and Central Europe, with special attention to the influence of climate and land use variability. During the early Holocene (Preboreal to Atlantic Period), most floodplains were rather stable with limited floodplain aggradation. After this initial phase of relative stability, sedimentation rates increase during the Middle and Late Holocene, with often the most important deposition phase during the last 1000 to 2000 a. The start of the increase in sedimentation varies spatially, with an earlier start in the west (France, Germany) then in the east (Poland, Belarus, Ukraine), while there are also local differences between regions which are settled early (e.g. loess regions) compared to later settled regions. The sedimentation history of most floodplains can be linked to the local land use history, while influence of climatic variations on floodplain aggradation is often reported to be of minor importance. Processes related to bedload are often reported to be more influenced by climatic events. Relationships between the driving forces and the sediment history are mainly based on synchronicity, and there is seldom proof for a direct causal relationship. Future research should focus on a system-based approach, integrating the floodplain deposition in the entire sediment dynamics which includes also erosion, colluvial deposition and export. Main research questions that need further attention include integration of system-based concepts, like landscape connectivity and buffering effects, and also the assessment of the individual contribution of land use changes and climatologic variations on the sediment dynamics. Detailed sediment budget studies combined with modeling studies can make an important contribution to the understanding of floodplain sediment dynamics.