Utilizing Morphotectonic Indices to Study Faults Impact on Darparchin Watershed Morphology

Darparchin watershed is one of the Bidvaz river sub-basins and it is located in northeast Iran. Apparent morphology, fault scarps, and debris indicate influence of tectonic structures like faults on the watershed development. Owing to vicinity with residential and industrial areas (such as Esferayen city and Bidvaz dam) and basin arrangement purposes, knowing about the impact of tectonic structures to this basin is necessary. For this aim longitudinal and logarithmic profiles of the basin, and its morphotectonic indices, vf, AF, s, and lat were obtained, and Gravelius impact factor for each of them has been identified. The postulation of profiles showed a lack of harmony as in most parts the longitudinal profile is above another one. This repugnancy is consistent with faults orientation. The vf index in 19 stations was measured with an average value of 0.7859. Based on this index faults are active and they caused tight (V-shaped) valleys in the basin. Results of AF index in this basin showed a compaction on right side of the basin because of the faults pressure from north direction to this part of basin. Also results from Gravelius factor announced that the basin stretched and continued to trend NW-SE by reason of faults direction. In field studies various types of karst forms such as karrens,ponor, dolines, and karstic valleys were observed, which were related to faults with perpendicular direction to stretched valleys.