River Environments, Climate Change, and Human Impact

Abstract

In this chapter a short overview of the evolution, geomorphological expression, sedimentary records, and discharge and sediment regimes of the major rivers in western Europe is presented. The rivers Elbe, Weser, Rhine, Meuse, Scheldt, Seine, Loire, Garonne, Rhône, and Danube will be separately reviewed but not necessarily in this order and not with equal attention. Emphasis is placed on the Quaternary record and most issues are exemplified by a discussion on phenomena and processes in the Rhine–Meuse delta. As almost all these rivers are strongly influenced by man’s activities, attention is also focused on river management practices, both in a historic context and at present. Finally, modern concepts and plans concerning river conservation and rehabilitation are briefly examined. The foundations of the modern drainage system in north-western Europe were laid in the Miocene when earth movements associated with Alpine orogenesis and the opening of the North Atlantic were at their height (Gibbard 1988). During the Late Tertiary–Early Quaternary the North Sea basin was dominated by an extensive fluvial system that drained the Fennoscandian and Baltic shield through the present Baltic Sea (Overeem et al. 2001; Fig. 6.2). The dimensions of this (former) drainage system were enormous; through empirical relationships based on recent fluvio-deltaic systems the drainage area is estimated to have been in the order of 1.1 × 106 km2. Cenozoic marine and fluvial sediments reach a thickness of more than 3,500 m in the North Sea basin. Quaternary sediments with a thickness of over 1,000 m imply a tenfold increase in sedimentation during this period in comparison to the Tertiary infilling. The fluvial system of Miocene to Middle Pleistocene age has been referred to as the Baltic River system (Bijlsma 1981). It is also designated as the Eridanos delta system by Overeem et al. (2001) named after the legendary Eridanos river in northern Europe mentioned in Greek records (7th century BC). In a seismo-stratigraphic study Overeem et al. (2001) have documented the large-scale basin-fill architecture in terms of external forcing by tectonics, sea-level variations, and climate. The development of this drainage system is attributed to the simultaneous Neogene uplift of the Fennoscandian Shield and the accelerated subsidence of the North Sea basin.