3D Geostatistic interpolation and geological interpretation of palaeo-groundwater rise within the Holocene coastal prism in The Netherlands

Coastal prism sediments record rising local water levels, forced by sea-level rise. This rise is quantified by dating series of organic markers of palaeo-groundwater levels at compaction-free locations. The data set of palaeo-groundwater levels (>300 index points) with a dense spatial and temporal coverage and predictive quality enables geostatistical analysis. Groundwater rise is interpolated for the entire delta (120 km land inward, 60 km wide) between an 11.0 kyr BP groundwater low stand and the present high stand. The input data and interpolation method (a form of 3D-kriging) reveal the interplay between upstream (climate, discharge) and downstream (sea level, tides) controls on groundwater level gradients, and patterns of groundwater rise. Sea-level rise is the primary driving factor, but the anatomy of the coastal prism is a result of a complex interplay of sea level, subsidence and upstream controls (essentially sediment load). Regional effects due to local controls (differential subsidence, groundwater flow) are identified. Groundwater rise is linked to sedimentary architecture. It is shown that back-filling continues into the Late Holocene, when eustatic rise had ceased. The results corroborate earlier results on differential subsidence and post-glacial enhanced subsidence in the delta. Moreover, the 3-D geostatistical interpolation opens possibilities to test and further develop process-based models for deltaic deposition.