Survey of Geomorphic and Morphotectonic Indixes to Assessment Active Tectonics in Khorram Abad River

Khorram Abad plain is situated on the folded Zagros unit and Khorram Abad River, as a distributary of the Karkheh River, flows through this plain. Since Khorram Abad’s hidden and active fault is positioned in this region, it is severely influenced by the neotectonic activities of this fault. Therefore, the present study aimed at the investigation of the effect of this fault’s activities on the morphological activities of Khorram Abad River using remote-sensing techniques, geometrical indices, aerial photos, and satellite images and field measurements. To do so, the river’s route was seminally divided into five subareas for attaining more precise results and the aerial photos were taken in 1955 were compared and Google Earth’s 2016 images were processed in GIS. Digitization of the river’s route in AutoCAD enabled the specification of the geometrical indices like river’s slope and gradient and sinuosity amounts for the abovementioned five subareas; the longitudinal profiles and the changes in the alluvial terraces were measured in field observations. The values obtained for Khorram Abad River’s geometrical indices indicated that Khorram Abad’s anticline and its upstream regions are upheaving and the downstream regions are subsiding or maintaining their previous positions. This ascending trend has been followed by an average gradient along the river’s route and is manifested in the form of a change in the number of the tributaries and geometrical properties of the river.