Spatial Analysis of Landslides in Relation to Active Tectonics Based on Morphotectonic Indices in Kheirabad River Basin

Neotectonic activity plays an important role in increasing the occurrence of landslides. The purpose of this study is to investigate the relationship and the extent of landslide occurrence from active tectonics in the Kheirabad River Basin River. For this purpose, neotectonic activity in four sub-basins of this river and based on six morphotectonic indicators; V/A, Bh, P, BR, Ff, and Tf were calculated. The mentioned indices were extracted in each sub-basin using Arc GIS 10.4 software and digital elevation model (DEM 10 M) as well as the Archydro plugin. Each index was divided into three categories in terms of tectonic activity, and finally, based on the segmentation of each index, the level of tectonic activity of the region was determined on the basis of the index of relative tectonic activity index (Iat). And the area of the study was divided into 3 categories. The results showed that neotectonic activity is very high in Shahbahram sub-basin and high tectonic activity in Dehdasht and Sarpari sub-basins and low tectonic activity in Kheirabad sub-basin., Finally, by cross overlaying of the landslide inventory map to the relatively active tectonic zonation map, the percentage of landslides that occurred in each tectonic region and the role of active tectonics in landslide occurrence was determined. The results showed that 74.69% (587.75 ha) of landslides occurred in the area with high tectonic activity, which covers only 33.11% of the total area of the study basin. Accordingly, 199.09 hectares of landslides occurred in areas with moderate and low tectonic activity, which constitutes more than 66/89% of the total basin. This distribution indicates the dependence of the landslide occurring with active tectonics, in other words, the role of active tectonics in the occurrence of landslides.