Calculating connectivity patterns in delta landscapes: Modelling Roman and early-medieval route networks and their stability in dynamic lowlands

摘要

River landscapes can be regarded as amongst the most densely populated regions in the world. Despite their dynamic nature and their susceptibility to natural hazards, pull factors such as fertile soils and trade connections always have attracted people to these regions. During the Roman (12 BCE - 450 CE) and early-medieval periods (450 CE-1050) the Rhine-Meuse delta in the Netherlands underwent significant simultaneous cultural and environmental changes such as changing settlement patterns, the collapse of the Roman limes, changing flooding regimes and river avulsions. Past route networks are influenced by both cultural and natural dynamics and are therefore a useful tool to better understand the complex interaction between these dynamics. By applying and enhancing recently-developed methods of modelling route networks in dynamic lowlands, this study reconstructs connectivity patterns in the Rhine-Meuse delta. Based on newly-available high-resolution geoscientific and archaeological data, network-friction maps and route networks were calculated for three time slices: 100 CE, 500 and 900. These modelled networks were validated using archaeologically-excavated infrastructural and isolated finds. Additionally the amount of network stability between these networks was calculated. Results show that for each of the route zones a clear correlation exist between the modelled network and the occurrence of infrastructural and isolated finds. Although clear periodic differences between these correlations percentages are visible. Despite the dynamic nature of the research area the routes show clear signs of network stability, with 80% of the 500 CE network being persistent with their 100 CE counterparts. Between 500 CE and 900 CE the persistence percentage slightly rises to 81% indicating a similar level of network stability. This shows that large parts of the Rhine-Meuse delta were persistently used during the Roman period and Early Middle Ages despite local settlement dynamics and changing natural settings. (C) 2017 Elsevier Ltd and INQUA. All rights reserved.