by Kim Cohen
Esther Stouthamer, Wim Hoek, Kim Cohen (2012) Mapping of the Holocene Rhine-Meuse delta - The 'Berendsen Map'. In.: Floor (coord. ed.) Dutch Earth Sciences - development and impact, The Hague, KNGMG, p. 176.
A map figure covering the full delta, supplemented with a historic overview of the displayed mapping, and a figure... more
A map figure covering the full delta, supplemented with a historic overview of the displayed mapping, and a figure caption highlighting the main features of the delta, illustrated with the map and outcome of a long series of PhD thesises from our group, serving as an example of progress in delta mapping in the 100 years of existence of the Royal Netherlands' Society for Geology and Mining (KNGMG). The rest of this abstract is the figure caption (K.M. Cohen, 2011).
Distribution, Age-of-Abandonment and Network Evolution of Fluvial Channel Belts in the Rhine-Meuse delta (Holocene, The Netherlands. Mapping based on ca. 250.000 shallow boreholes collected since 1950. Dating based on ca. 1500 14C dates on fluvial depositional elements and >30.000 catalogued archeological finds, in known stratigraphical context. Background topography from laser altimetry (www.ahn.nl). Delta network queried from the Utrecht Rhine-Meuse Delta Studies' GIS system for delta palaeogeography reconstruction, originally developed for Berendsen & Stouthamer (2000, 2001) Stouthamer (2001): see Berendsen, Cohen, Stouthamer (2007). Updated 2003, 2007, 2011 (Cohen, 2003; Gouw, 2007, 2008; Erkens, 2009; Bos, 2010; Stouthamer et al., 2011).
Feature description: (i) Delta is bound by Pleistocene ice-marginal topography, including terminal ice-pushed ridges of the Saalian Drenthe Substage maximum limit, ca. 150,000 years ago. (ii) Delta is protected by the Middle-Late Holocene Holland coastal barrier system. (iii) major 19th and 20th cy reclamations in the central Netherlands' lagoon and works at the Amsterdam and Rotterdam harbours bound the modern delta. Diggings, embankments and reclamations in the delta plain go back to Medieval times, starting 1000 years ago. The southwest of the delta is an estuary network resulting form Medieval storm surge ingressions into early reclaimed lands, and human response hereto. (iv) In the central delta, the Rhine is joined by its tributary the Meuse. The rivers share estuaries and tidal river reaches in the delta. (v) Middle Holocene deltaic channel belt avulsions occurred, during and following transgression that made the delta form at its present position. Despite avulsions, however, the trunk channel system remained in position at the Northern edge of the pre-transgression valley: only minor Rhine branches were active to the south, and trunk channel avulsions were always northward. (vi) A major avulsive network reorganisation occured in the Late Holocene, commencing in the last millenium BC, a marked trend break with the five millenia of delta evolution before.The reorganisation was triggered in the upper part of the delta, as a response to increased loads of fine sediment, delivered from the prehistoric deforested hinterland. New northward distributaries avulsed and found the central Netherlands' lagoon. New southwestward distributaries avulsed and found the Meuse estuary, and gradually became the major branches. This culminated in abandonment of the former Rhine trunk channel and its northerly outlet at the time human embankments began (11th cy AD). (vii) The network reorganization, initiated at the upstream side of the delta, at the downstream end caused the abandonment of the matured Leiden outlet, where the river had long injected sediment into the open North Sea. It replaced this outlet with a mouth into Rotterdam estuary, which trapped more and more Rhine bed load, as the avulsed branch gained importance. At the beginning of the first millenium AD, this triggered major coastal reorganisation along the Zeeland-Holland coastal barrier system, further helped by the additional accommodation created by auto-compaction that occured where clay buried peats and by storm surges that eroded reclaimed peat land and created new estuaries and new inshore trapping space for Rhine-Meuse sediments.
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