change of pattern

Karun River with a length of about 890 Km is considered as a main river in the country. In this paper، types of Karun’s screws regarding to the geometric factors of radius of curvature and chord length were identified by fitting circles with the arcs of the river’s axis. River’s arcs were classified into simple and compound screws. Then، by formation of the database consist of topographic maps (1:50000)، Landsat satellite images of 1973 and IRS images of 2006، multi-time images were processed in ERMapper and GIS to determine the rate of meanders variations in a 51- years interval and finally map of changes was drawn. The results illustrated that from 149 meanders which exist in region، 21 meanders have changed from simple to compound and vice versa. Most of variations are related to the change of simple meander into compound meander. In some regions changes in river’s pattern were identified، so that 7 meanders have changed from simple pattern into arterial pattern. Another significant change is observable in the end of the Karun’s route (Bahmanshir River) which is related to the increasing of the 2 new meanders in the meandric route of the River.