1 Radiocarbon date
Cone penetration test Coring
Penetration depth
1 km 0
Scale
Legend
Undifferentiated peat
Clay Wood peat Phragmites peat
Flood/tidal basin
Gyttja Humic clay
Silty clay Sandy Clay
Fluvial/tidal channel belt
Crevasse channel (most likely fluvial) Channel deposits (most likely fluvial) Channel base (uncertain)
Loam
Channel deposits Aeolian river dune Aeolian coversands Vegetation horizon Oligotrophic peat
Channel deposits (most likely marine, Walcheren) Channel deposits (most likely marine, Wormer)
Older than Kreftenheye Pleistocene deposits
Universiteit Utrecht
New Rotterdam sea-level indicators (Hijma, in prep.; Boor, Internal reports) sea-level curve western Netherlands (Van de Plassche, 1982)
Inferred new groundwater/sea-level curve
Rate of combined SLR and subsidence
~ 3-4 m/1000 yr
Rate of subsidence
~ 0.5 m/1000 yr
Rate of subsidence
~ 0.3 m/1000 yr Rate of combined SLR and subsidence
~ 1-2 m/1000 yr
Time (ka BP)
Achterlaan Zoetermeerse laanA12 Highway
Nieuwe Hoefweg (N209)
Westeinde
Nieuwe Maas Rotterdam Barendrecht
Rotterdam
Early Holocene Drowning of the Rhine River Mouth
Marc P. Hijma and Kim M. Cohen
1, 2 1First draft central cross-section: from the Old Rhine to the Hollandsch Diep
N
N N
S
S
Study area and location of the cross-section
Utrecht Centre of Geosciences, Department of Physical Geography, Faculty of Geosciences, Utrecht University, P.O.Box 80.115, 3508 TC Utrecht, The Netherlands, m.hijma@geo.uu.nl TNO Built Environment and Geosciences – Geological Survey of the Netherlands, P.O.Box 80.015, 3508 TA Utrecht, The Netherlands
S E A - L E V E L C U RV E
During this study we collected new sea-level indicator points by dating peat-layers and were able to extend the existing curve back in time from 7500 to 10000 years ago.
In the figure above a part of the new data is presented. It indicates that SLR was less steep in the period 8000-9000 years ago then earlier was assumed by extrapolating the Van de Plassche-curve.
The Pleistocene surface around Rotterdam lies -17/-18 m below NAP. At this depth the curve flattens (10000-9000 BP). It reflects rising groundwater levels not yet influenced by SLR.
Sea-level in the western Netherlands has always been rising because of continuous subsidence. Between 8500 and ~3000 years ago this rise was enhanced by a global sea- level rise signal.
1
2
zoet poelslakken
Middelsluisse Dijk OZ Boomdijk
Oudendijk Ritselaarsdijk
Blaaksedijk Blaaksedijk Oost
Mollekade
Binnenbedijkte Maas Oude Maas
O.D.
(NAP) +5 (m)
-5
-10
-15
-20
-25
-30
H4 PI 0019 H4 PI 0003 H4 PI 0004 37H0469 37H0224 37H0220 37H0221 37H0222 428-094-0001 37H0227 37H0226 37H0225 43F0019 416-092-0001 416-092-0002 418-093-0002 43F0032 417-093-0002 417-093-0005 416-093-0004 421-094-0012 43F0031 420-094-0003 420-093-0005 419-093-0004 419-093-0001 43F0030 418-093-0003 422-094-0001 422-094-0006 421-094-0002 421-094-0006 420-094-0005 420-094-0004 421-094-0001 423-094-0007 423-094-0002 423-094-0011 423-094-0012 422-094-0007 422-094-0002 424-095-0002 43F0013 424-095-0001 424-095-0010 423-095-0016 423-095-0015 423-094-0003 425-095-0006 37H0027 37H0099 425-095-0009 43F0014 424-095-0003 425-094-0002 425-094-0005 425-094-0006 425-094-0007 37H0240 425-094-0003 427-094-0003 426-094-0004 37H0238 426-094-0009 426-094-0003 37H0239 07.09.002 07.09.003 07.09.004 07.09.005 07.09.026 07.09.027 07.09.032 07.09.028 07.09.031 07.09.030 07.09.029
Mainly braided river deposits (Kreftenheye Formation)
Older Pleistocene deposits
Coversands Mainly braided river deposits (Kreftenheye Formation)
Coversands
Relative sea-level (m below NAP)
C R O S S - S E C T I O N
In the cross-section below, the drowning of the delta is visualized. At the base of the Holocene purely fluvial deposits are present, to the top the sediments are from an increasingly wet and brackish environment.
New dates, pollen and diatoms research will further improve our understanding of the fluvial-marine transition zone.
11 10 9 8 7 6 5 4 3 2 1 0
-10
-14 -12 -8 -6 -4 -2 0
-20 -18 -16
Old Rhine Marine deposits Marine deposits
Fluvial deposits
Fluvial deposits
Marine deposits Peat
Peat
These areas are densely populated and it is therefore important to understand how coastal and fluvial processes interact under drowning.
Below the surface in the western Netherlands lies a very well preserved sediment body dating from a rapid drowning period 10000-8000 years ago (early Holocene). We study it. Here we present two parts of the study: a sea-level curve and a cross-section.
North Sea
Seismic data
Transects
Rotterdam The Hague
Borehole data
Borehole data
THE RESEARCH
Worldwide, humanity has faced sea-level rise (SLR) for more than 20000 years now. In the western Netherlands (Rotterdam area) the direct impact started only 10000 years ago, when groundwater levels started to rise rapidly and the landscape changed from a river valley to an estuary.
Today, we face an increase in sea-level rise and river mouths start to drown on a global scale
.O.D.
(NAP) +5 (m)
-5
-10
-15
-20
O.D.
(NAP) +5 (m)
-5
-10
-15
-20
** *
O.D.
(NAP) +5 (m)
-5
-10
-15
-20
-25
-30
-35 O.D.
(NAP) +5 (m)
-5
-10
-15
-20
-25
-30
-35
O.D.
(NAP) +5 (m)
-5
-10
-15
-20
-25
-30
