Reconstructing Phreatic Palaeogroundwater Levels in a Geoarchaeological Context: A Case Study in Flanders, Belgium

Abstract

The complex debate on prehistoric settlement decisions is no longer tackled from a purely archaeological perspective but from a more landscape‐oriented manner combined with archaeological evidence. Therefore, reconstruction of several components of the former landscape is needed. Here, we focus on the reconstruction of the groundwater table based on modeling. The depth of the phreatic aquifer influences, for example, soil formation processes and vegetation type. Furthermore, it directly influences settlement by the wetness of a site. Palaeogroundwater modeling of the phreatic aquifer was carried out to produce a series of full‐coverage maps of the mean water table depth between 12.7 ka and the middle of the 20th century (1953) in Flanders, Belgium. The research focuses on the reconstruction of the input data and boundary conditions of the model and the model calibration. The model was calibrated for the 1924–1953 time period using drainage class maps. Archaeological site data and podzol occurrence data act as proxies for local drainage conditions over periods in the past. They also served as a control on the simulated phreatic palaeogroundwater levels. Model quality testing on an independent validation data set showed that the model predicts phreatic water table levels at the time of soil mapping well (mean error of 1.8 cm; root mean square error of 65.6 cm). Simulated hydrological conditions were in agreement with the occurrence of archaeological sites of Mesolithic to Roman age at 96% of the validation locations, and also with the occurrence of well‐drained podzols at 97% of the validation locations.

Modeling Soil Processes: Review, Key Challenges, and New Perspectives

“…To deal with extremely long time scales, models should be able to incorporate long‐term changes in climate, landforms, and other relevant boundary conditions. Integrated methodological approaches need to be developed to verify such models beyond the time‐scale of instrumental observations, for example, by including proxy variables serving as (paleo)indicators of past hydrological conditions (e.g., vegetation, soil, or historical archives; Zwertvaegher et al, 2013; Zlinszky and Timár, 2013). As in simulating soil formation, many input variables are uncertain since they are in essence unknown for future conditions.…”

Reconstructing a prehistoric topography using legacy point data in a depositional environment

“…The most striking feature is the substantial and rather certain thickness of Holocene sediments in the western part of the Moervaart depression and the eastern parts of the floodbasins of Sleidinge (Figure 1, Figure 6: area 2). In the same study area, Zwertvaegher et al (2013a) concluded, based on simulation of the palaeohydrology, that the early Holocene was characterized by a rapid increase of groundwater levels and a decrease in spatial wetness gradients, leading to a less attractive landscape for hunter-gatherers. In the same study area, Zwertvaegher et al (2013a) concluded, based on simulation of the palaeohydrology, that the early Holocene was characterized by a rapid increase of groundwater levels and a decrease in spatial wetness gradients, leading to a less attractive landscape for hunter-gatherers.…”

Resolving the integral connection between pedogenesis and landscape evolution

“…In stable landscapes with shallow water tables, a 3D-groundwater model can be applied to generate the lower boundary condition (e.g., a time series of the annual average water table depth) for the 1-D profile model (Zwertvaegher et al, 2013a). After running the 1D-model, the results are again interpolated (Zwertvaegher et al, 2013b).…”