Plat e 1. Duri ng th e Holocene th e present Rhine-Meu se deltaic plain was form ed, far inl and from th e lowst and deltas. The delt aic plain, which still conta ins glacial features, can be subdivided into a fluvial area, an estuarine area, and a coast al dune area. Journal of Coastal Research 740-752 Royal Palm Beach, Florida Summer 1998 Birds-Eye View of the Rhine-Meuse Delta (The Netherlands) H. J. A. Berendsen Faculty of Geographical Sciences Utrecht University Heidelberglaan 2 3508 TC Utrecht, The Netherlands ABSTRACT . BERENDSEN, H.J.A., 1998. Birds-Eye View of the Rhine-Meuse Delta (The Netherlands). Journal of Coastal Re­ .ttlllllll:. search, 14(3), 740-752. Royal Palm Beach (Florida), ISSN 0749-0208. ~ ~. The Rhine was formed in the Miocene. During the Pleistocene it dumped large amounts of glacial debris into the _____ :.......A....: r:J subsiding North Sea Basin, which resulted in a maximum thickness of Quaternary deposits of about 1000 m. During --A w the Holocene the present deltaic plain was formed, far inland from the lowstand deltas. The deltaic plain, which still ... .-JU contains glacial features, can be subdivided into a fluvial area, an estuarine area, and a coastal dune area. Sea level rise played an important role in the Holocene evolution of the deltaic plain. The abandunce of sand in the shallow North Sea basin caused progradation of the coast, once the rate of sea level rise decreased (after 5000 BP). Human influence in the delta has been great since the Middle Ages: peat was dug, lakes were drained, and new land was gained by building new dikes and draining the enclosed areas, tidal inlets were closed by dams, thus profoundly influencing hydrology and ecology. This paper provides a review of these components of the Rhine-Meuse delta in addition to potential future developments along the coastal area. ADDITIONAL INDEX WORDS: Geology, natural environment, sea level rise, human influence Rhine-Meuse delta. INTRODUCTION sedimentation in a back-barrier area or by peat formation. Outside the present river mouths, estuarine and tidal flat The Rhine-Meuse delta of the Netherlands is one of the areas prevail. On the longer time scale of the Quaternary best studied deltaic areas in the world. Its high population (Figure 2), however, practically the entire Netherlands is part density (15 million inhabitants in an area of only 35,000 km") of a delta formed by the rivers Rhine, Meuse, Scheldt, Elbe and high level of industrialization, together with the natural and Weser. conditions (a weak subsoil and about 400/0 of the country lying The present mean annual discharge of the Rhine is ap­ below sea level) require a thorough knowledge of natural con­ proximately 2200 mvs; that of the Meuse is smaller by about ditions to protect the country from the sea and flooding by a factor of ten (Table 1). the rivers, and, at the same time, to maintain a balanced environment. This explains the Dutch preoccupation with the sea. Tertiary and Pleistocene In this paper an overview is presented of the geological The oldest sediments of the Rhine date from the Miocene history, human influence, present-day and future problems when it was a small stream draining the graben of the Lower associated with the Rhine-Meuse delta. The origin of the riv­ Rhine Embayment. From a geological perspective, the apex er and the formation of the deltaic plain is first reviewed, of the Rhine delta, therefore, is located near Bonn (Germany), followed by an overview of the present situation and possible where the Rhine leaves the Rhenisch Massif and enters the future problems. North Sea Basin. The North Sea Basin formed because of Mesozoic stretching related to the opening of the Atlantic GEOLOGICAL FRAMEWORK Ocean (ZIEGLER, 1990). Neogene uplift of the Rhenish Massif General Characteristics (Germany) and the Ardennes (Belgium) led to increasing drainage areas both for the Rhine and Meuse. The alluvial The Rhine-Meuse deltaic area is situated in the southeast­ and delta plain sediments of this primitive Rhine and Meuse ern corner of the North Sea Basin, where it forms part of a cover much of the southeastern Netherlands. At the Pliocene/ coastal plain of varying width that extends from the Strait of Pleistocene boundary, the Rhine captured the river Aare Dover in the south to Denmark in the north (Figure 1). This (Switzerland), and extended its drainage area in the Alps area, although referred to as "the Rhine-Meuse delta," is not (ZONNEVELD, 1980), which is clearly demonstrated by the a delta in a strict sense (KRUIT, 1963). Virtually all of the heavy mineral composition (i.e., the presence of saussurite) of Holocene delta has a subaerial origin and was formed by river the Rhine sediments. Marine deposition predominated in the Netherlands (Fig­ 98139 received and accepted in revision 9 May 1998. ure 3, insert a) until the early Pleistocene (2.5 million years 742 Ber end sen ! ~ : ~ :~:f~ :~ : ~l sand ridges - - depth conto urs land o coastal slop e 11II1I:I 1:!tidal inlets of Zeeland A: Delta area !_ B: Coast of Holland (no tidal inlets) ~ c=J s ea floor Is/ope < 1:1000) wad de n area (tidal flats) C: Wadden area ~ WbD K Wijk bij Duurstede .. coastal dunes former Zuiderzee-Ia goon PK • Pannerdens Canal Figure 1. The North Sea Basin and subdivision of th e Dut ch coast (after Van de Meene, 1994). ago). General regression at the site of th e southern North Sea ta tion practically coincides with th e Dutch-German border , Basin began during the Pliocen e, and, despite increased sub­ which means that from a geomorphological point of view, al­ sidence during the Pleistocene, th e supply of debris was so most th e entire Netherlands can be seen as a delt aic plain. great that during the interglacial Tiglian (Figures 2 and 3, Sub sidence of the North Sea Basin increased considerably insert b) th e coastli ne at highstands was located seaward of in the Quat ernary: a Quaternary sequence of up to 1000 m the present coast (ZAGWIJN, 1989). Glaciation, both of th e th ick is reported from th e central part of th e North Sea area Balti c shield and the Alps was th e main cause for this rapid (BERENDSEN, 1997a). regre ssion. In addition to th e rivers Rhine and Meuse, large In the middle and lat e Pleistocene, the Scandinavian ice amounts of sediment were supplied by rivers draining th e ice caps reached the Netherlands (Figure 3, insert c). The EI­ cap of th e Baltic shield and debauching at the northeastern sterian ice cap scoured up to 400 m deep subgl acial channels side of the Netherlands. These latter rivers, as well as rivers in th e unconsolidated Quaternary sediments of the North Sea draining northern Germ any, supplied sediment until approx­ Basin (ZAGWIJN, 1989). The Saalian ice cap reached even far­ imately th e Middle Pleistocene (Early Cromeria n, Figure 2). ther south and significantly altered the landscape, forming Except for th e Pretiglian, the combined lowstand delta fronts 100 m high glaciotec tonic ridges (visible in Figure 3, insert of th ese rivers occur offshore (CAMERON et al., 1986; SHAand d) that are still important elements in the present landscape. DE BOER, 1991). Onshore alluvial plain sequences of early The Saalian ice front forced the rivers Rhine and Meuse to Pleistocene age exceed 100 m in thickness locally. shift their northern course westwards. Since th at time, thi s The area between Bonn and the Dutch border was uplifted ha s remained th e main course of the rivers. At present the during the Quaternary. Here , alte rn ating glacial and inter­ ridges control the width of th e fluvial plain, thereby deter­ glacial conditions produced a series of terraces (ZAGWIJN, mining th e areal extent of th e Holocene delt a. 1989). The hinge line between net erosion and net sedimen- By th e end of the Weichselian ( = Wisconsinan ) glaciation Journal of Coastal Research, Vol. 14, No.3, 1998 Birds-Eye View of the Rhine-Meuse Delta (The Netherlands) 743 Polarity Chronostratigraphy 0 o core V28-239 Deep-sea stages o0 -0.4 -0.8 -1 2 -1 6 0 .-Stage 1 (Holocene) Weichselian Eemian .-Stage 5 (Eemian) Saalian Holsteinian ~Stage7 Brunhes Elsterian 500 ==~=:~1_-Stage 13 Cromerian !!-Stage 15 ;-Stage21 1000 Bavelian ::-Stage31 Menapian -:-Stage39 Waalian ii- 1500 .-Stage 51 =-Stage57 Eburonian Olduvai ==~I:g:gj Iii 2000 liglian >- Reunion :: ("t) ~ cold warm X Pretiglian Q) -cC) 2500 Gauss cold warm Figure 2. Pleistocene stratigraphy (after Zagwijn and Van Staalduinen 1975, modified by Berendsen, 1997a). (in which the ice sheets did not reach the Netherlands) most rise to extensive river dune formation on the river plain (BER­ of the Netherlands became covered with eolian sands. The ENDSEN et al., 1993). These dunes are still visible in the pres­ Rhine and Meuse flowed westward through two valleys that ent-day landscape and, because of their relatively high ele­ are still visible in the morphology of the Late Glacial surface vation, became the site of early settlements. (Figure 3, insert d). ' Because of the morphology of the North Sea Basin, the During the Weichselian, sea level was at least 100 m lower Pleistocene lowstand deltas of the Rhine-Meuse system occur than today. In the shallow North Sea area, rivers had a com­ far seaward of the highstand deltas. Consequently, the Ho­ paratively low gradient. In the vicinity of the present coast­ locene wedge occurs not on top of the preceding lowstand del­ line downcutting of some 20 m could take place, resulting in ta, but overlies alluvial plain sediments of early-to-late Pleis­ deep late glacial valleys that influence the morphology of the tocene age on top of a delta front sequence of early Pleisto­ coastline and the course of the rivers until the present.