Investigating the Role of the Movements of Khorram Abad’s Hidden Thrust Fault in the Evolution of Khorram Abad River’s Drainage System

Khorram Abad plain is located in the folded Zagros zone and its River, as one of the main rivers discharging to Karkheh River, flows through this plain. This region is highly influenced by the neotectonic activities of this fault since Khorram Abad’s hidden and active fault is located in this region. Therefore, the current study aimed at the investigation of the effect of this fault’s activities on the morphological activities of Khorram Abad River.

This is an empirical study that is quantitative in terms of used data and calculations. Remote-sensing techniques, geometrical indices, aerial photos, satellite images, and field studies are used in the current research. For this purpose, the river’s route was divided into five subzones to be more precise. Then, the aerial photos taken in 1955 were compared to Google Earth’s 2016 images in GIS. Geometrical indices such as the gradient of the river’s slope and sinuosity of the mentioned five subzones were calculated by the digitization of the river’s route in AutoCAD; the profiles and the changes in the alluvial terraces were measured through field observations.

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 staying in their previous positions. This ascending trend has been followed by an increase in the average riverchr('39')s slope has changed the number of the tributaries and geometrical properties of the river.

The primary reason for the morphological changes in the Khorram Abad River is the geological movements. Then, the movements of Khorram Abad hidden thrust fault were the most important factors changing the morphology of Khorram Abad River in the studied period.