Paleogeography and Geomorphological Changes of the Ancient Seymarreh Lake

Various landforms have been created in different parts of the world by catas¬trophic events. One of these events, caused the landslide and separation of stony blocks from Kabir Kooh hillside and obstruction in the course of the river and formation the ancient Seymarreh lake. This lake is a dam lake and has created due to the huge Kabir Kooh landslide. This study area is located in the west part of Iran and in the Southeast Ilam province, in the folded Zagros. The lake bed has created an extensive urban and rural life in the region, for this reason the study and exact delimitation of the lake for an environment planning is important. The purpose of this paper is to study geomor¬phological changes of this lake. For studying the geomorphological changes of the lake, in the frequent field visits, the formed traces in the area were dete¬rmined and through Gps it's altitude were measured. For controling the ground measurements by using Global Mapper11 softwarethe topo¬graphic maps of the area with the scale of 1/50000 and the water way maps by the digital elevation model (Iran map dem) has been conformed. The softwares: Arc Gis9.3, Surfer 9 have been used for preparing and producing new maps and the lake measuring exact delimitation. According to the results of this study, the Lake delimit has been determined on the basis of sediment extension and contour line 700 meters. The Extent of this lake was found to be 174.16 〖KM〗^2, with the maximum depth of 159 meters, the medium depth of 52.67 meters, the ratio of average depth to the maximum of depth 0.33, degree of seaside evolution line was 3.3, lake volume 9172.43 million M^3and the seaside length line 154.02 kms.