Spatial differences in subsidence and relative sea-level rise in the Netherlands during the Holocene

LOSS researchers Kim de Wit and Kim Cohen published a new paper in Global and Planetary Change.

Long-term natural subsidence plays an important role in the Holocene relative sea level rise (RSLR) signal of the Netherlands. Differential subsidence estimates over this period can be retrieved from geological water level indicators, such as basal peats. In the Netherlands, long-term natural subsidence is mainly due to glacial isostatic adjustment (GIA) resulting from its position on the former forebulge of the European Ice Sheet (EuIS). Tectono-sedimentary basin subsidence related to the position in the south of the North Sea basin is a secondary component. In this paper, 3D kriging-with-a-trend was used for spatiotemporal interpolation of geological sea-level indicator data, from which a basin-subsidence trend was removed. The total RSLR signal was split into a water table rise and a GIA-related subsidence component. We extracted averaged RSLR rates for multiple time slices, from 8 ka to 2 ka, broadly reproducing previous site-centred RSLR reconstructions and upgrading these to a nationally covering spatially continuous grid. After 6 ka, GIA accounts for 90% of total RSLR. Towards the present, the GIA component decays, allowing the relative contribution of basin subsidence to increase, contributing up to 20% in the NW. The interpolation produces clear spatial-temporal patterns with regionally highest Middle Holocene GIA-subsidence rates in the N-NE (Waddenzee, Groningen). The spatially and temporally continuous reconstruction of Holocene RSLR provides a new analytical set-up for discerning component contributions to total RSLR. The interpolation output and derived subsidence rates are ready for confrontation with geophysical GIA-modelling and for further application in projections of future sea-level rise.