Generic 3Dinterpolation of Holocene base-level rise and provision of accommodation space, developed for the Netherlands coastal plain and infilled palaeovalleys
We present an interpolation model that describes Holocene groundwater level rise and the creation of accommodation space in 3D in the Rhine-Meuse delta – the Netherlands. The model area (ca. 12 400 km2) covers two palaeovalleys of Late Pleistocene age (each 30 km wide) and the overlying Holocene deposits of the Rhine-Meuse delta, the Holland coastal plain, and the Zuiderzee former lagoon. Water table rise is modelled from 10 800 to 1000 cal. BP, making use of age-depth relations based on 384 basal peat index points, and producing output in the form of stacked palaeo groundwater surfaces, groundwater age-depth curves, and voxel sets. These products allow to resolve (i) regional change and variations of inland water table slopes, (ii) spatial differences in the timing and pacing of transgression, and (iii) analysis of interplay of coastal, fluvial and subsidence controls on the provision of accommodation space. The interpolation model is a multi-parameter trend function, to which a 3D-kriging procedure of the residuals is added. This split design deploys a generic approach for modelling provision of accommodation space in deltas and coastal lowlands, aiming to work both in areas of intermediate data availability and in the most data-rich environments. Major provision of accommodation space occurred from 8500 cal BP onwards, but a different evolution occurred in each of the two palaeovalleys. In the northern valley, creation of accommodation space began to stall at 7500 cal BP, while in the southern valley provision of new accommodation space in considerable quantities continued longer. The latter is due to the floodplain gradient that was maintained by the Rhine, which distinguishes the fluvial deltaic environment from the rest of the back-barrier coastal plain. The interpolation results allow advanced mapping and investigation of apparent spatial differences in Holocene aggradation in larger coastal sedimentary systems. Furthermore, they provide a means to generate first-order age information with centennial precision for 3D geological subsurface models of Holocene deltas and valley fills. As such, the interpolation is of use in studies into past and present land subsidence and into low land sedimentation.