Roman and early-medieval habitation patterns in a delta landscape: The link between settlement elevation and landscape dynamics

Abstract

Settlement locations in delta landscapes change through time because of cultural and natural dynamics. We assessed the impact of natural-landscape dynamics on settlement-location shifts for the Rhine-Meuse delta in the Netherlands during the Roman and early-medieval periods (12 BCE-450 CE and 450-1050 CE respectively). During this time interval major landscape and cultural changes occurred in this area, with river avulsions and changes in flooding frequency coinciding with changing settlement patterns. In the delta plain, the relatively high and dry alluvial ridges of abandoned or active rivers were most favourable for habitation. Settlement location and elevation patterns were reconstructed in these landscape units using a high-resolution elevation map of the alluvial ridges. By integrating high-resolution palaeo-environmental and archaeological datasets for this period, we were able to spatially analyse the trends and to assess the effect of environmental changes on habitation. Results show that settlements progressively shifted towards higher areas between 250 and 750 CE, on average by 20 cm over this period deltawide, which was coeval with an increased frequency of severe Rhine floods. The observed spatial differences demonstrate that this trend is most notable in the least-elevated segments of the study area. In areas where new large river branches developed, settlements show a strong shift towards higher-elevated parts of the landscape or even became completely abandoned. The river probably caused floods to be more frequent and more severe in these areas. Despite the clear link between changing settlement positions and floods during the studied time interval, floods do not seem to have caused long-term abandonment of major parts of the study area.