The formation of Saymareh Dam Lake and its impact on the settlement's pattern of archaeological sites

IntroductionEnvironmental changes, such as changes in lake levels and changes alluvial environment and its effects on the settlement pattern of archaeological sites, represent the human dependence on environmental resources. Findings of the Zagros region, suggesting climate change and the environment and creating opportunities and threats to human societies in the past. Archaeological evidence shows that human societies during the Holocene in settlements located in this area have been established. The occurrence of landslides in the river path and formed a dam lake in the alluvial environments such as saymareh basin with water and fertile soil, not only causes the environmental changes but also can lead to displacement, loss, or changes in the settlement’s pattern of archaeological sites within the lake area. In the early Holocene big kabir kuh landslide occurred, causing the formation Saymareh Lake. Kabir-kuh landslide and the formation of Saymareh Lake in four stages have caused some changes in the settlement’s pattern of archaeological sites within the lake. The aim of this study is to investigate different effects of formation of the Saymareh Lake on the settlement’s pattern of archaeological sites in the lake area.
Materials and methodsIn this study, the basic information of Saymareh basin has been gathered using tools such as the position and cultural period of archaeological sites, topographic and geological maps, satellite imagery, digital elevation models, software, Arc GIS, Global Mapper, and field studies. Using these tools and field studies, the highest level of terraces lake’s sediments using GPS was obtained and the area of the Seymareh Lake and its terraces was determined based on the contour line of 700 meters. Then, the position specific sites on the lake terraces were determined and a polygon characterized by the height of the preparation of terraces was provided, and finally a 3-dimensional model of the lake terraces was drawn. Finally, the archaeological sites were classified based on their periods, overlapped on the terraces and then were analyzed in relation to each of the phases in which the lake has been formed. In the end, overlapping of sites on the terraces has been utilized to estimate the occurrence of landslides and the formation of the lake.
Results and discussionStudies which have been done on Kabir-Kuh landslide and Saymareh Lake, confirm the occurrence of landslides in the early Holocene. However, the lake varve, sediment thickness and the establishment of the archaeological sites during the prehistoric on the lake terrace in the first and second stages, show that landslides occurred in the late Pleistocene and early Holocene. As a result of occurrence of Kabir-Kuh landslides in four stages and the formation of four lakes, lake terraces can be seen as a stairs in 4 different levels. Distribution of more than 300 archaeological sites on the terraces represents human’s establishment from the Neolithic period to the Islamic period in this area. Most sites are located on the first terrace and the lowest density is on the fourth terrace. This represents a decrease in the area of the lake from the first to the fourth stage. Overlapping of the sites on the first terrace represents that Neolithic sites have been formed on the terraces, so the first stage has been the formation of the lake before the Neolithic period. The second phase of the Lake has happened with a time lag after the first stage and its wideness has been smaller rather than the ones of the first phase. The existence of the Neolithic sites on the surface of the terraces also shows the formation of the lake was in the second stage before the Neolithic period. There is a long periods between the third and the fourth stages of the formation of the lake before and lakes also had less vastness than the one’s of earlier. The lack of archaeological sites before Bronze Age on the third and fourth terraces represents lakes of the third and the fourth stages were formed after the Chalcolithic period. Moreover, within all four levels of the lake terraces, the highest density of sites belongs to the Islamic period.
ConclusionBased on field studies and the distribution of archaeological sites that have been done on the lake level terraces, phases one and two of the lake were formed before the Neolithic period. Neolithic sites have been established on deposits of lake sediments after drying, because according to studies that has been done after draining the lake, the lake had become a wetland like and then sediment would have been dried. At this point, after a long delay in the settlement area of residence, the first settlement has been formed. Due to the vastness of the lake at the third and fourth phases and distribution of the sites on the surface of sediments, it seems that there have not occurred a lot of changes in the settlement’s pattern of the sites in this process.