Effect of natural risk factors upon the evolution of Chalcolithic human settlements in Northeastern Romania (Valea Oii watershed): From ancient times dynamics to present days degradation

This study concerns the analysis of the Valea Oii watershed and the dynamics of human settlement depending on the occurrence of natural risk factors and their evolution. These include climatic change fluctuations, and appearance of new hydrological resources like springs, from consequent landslides, the disappearance of forests as a direct effect from overexploitation of the land. Archaeological sites and current villages have been investigated, as well as their emplacement depending on natural hazards (such as floods, landslides and gully erosion). At the same time, we have also indexed the water sources which include streams, springs and man-made lakes. The first archaeological records date back to the Chalcolithic period. The entire catchment includes a total of 26 Chalcolithic archaeological sites which are continuously threatened by numerous natural or anthropic risks. The morpho-hydrographic, geologic, and pedologic particularities have determined an early occupation of the area situated in the upper part of the watershed. In ancient times, the lower sector of the valley and the floodplain was used for agricultural purpose or for pasturing. Throughout time, human settlements shifted gradually towards the lower area. This phenomenon was triggered by significant deforestation, which led to an extension of the pastures and of the agricultural land. In the modern period, most settlements moved towards areas that were submitted to flooding. This process was determined by the escalation of landslides and by gully erosion which began after deforestation. In order to protect the floodplain settlements, dams were built to reduce the effects of high waters. One of the main advantages of studying small catchments is that the results can be extrapolated for larger catchments (> 100 km2), the volume of analyzed data being smaller, but done with the same strictness. Therefore, the results of this study can surely provide important information and can save relevant archaeological and geographical data in a GIS which, in normal present conditions, would not be possible to be recovered in the future.