Evaluation of the impact of tectonic activity on the morphometry drainage system the Alamut River basin, Qazvin

Document Type : Applied Article

Authors

1 Phd Student Geomorphplogy, Faculty of Earth Sciences, Shahid Beheshti University, Tehran

2 Associate Professor of Geomorphology, Faculty of Earth Sciences, Shahid Beheshti University, Tehran

3 Associate Professor of Sedimentary Basins and petroleum Department, Faculty of Earth Sciences, Shahid Beheshti University, Tehran

10.22059/jhsci.2026.411980.925

Abstract

The Alamut River basin, located in the Central Alborz Mountains of northern Iran, lies within an active compressional tectonic regime and is strongly influenced by regional fault systems. This study aims to evaluate the level of tectonic activity and to clarify its role in controlling the drainage network pattern using quantitative geomorphic indices. The analysis was conducted on 23 sub-basins (9 on the left bank and 14 on the right bank) based an ALOS digital elevation model (12.5 m resolution), 1:100,000 geological maps, 1:25,000 topographic maps, and satellite imagery within a GIS environment. The applied geomorphic indices include the ratio of first-order streams to total streams (N₁/N), drainage density (Dd), first-order drainage density (Dd₁), drainage frequency (Df), mean stream spacing (SMD), percentage of basin asymmetry (PAF), and drainage basin orientation (DBO). The calculated indices were normalized and classified using the quartile method into four tectonic activity classes ranging from low to very high. The results reveal a spatially heterogeneous distribution of tectonic activity across the basin. Higher tectonic activity is concentrated in the eastern, southeastern, and northeastern sub-basins (notably R13, R12, R8, L9, and L2), whereas the central and western parts exhibit relatively lower activity levels. The spatial correspondence between high-activity zones and the Alamut and Taleghan fault systems indicates strong structural control over drainage development. Elevated values of morphometric indices in active sub-basins suggest ongoing uplift, structural tilting, and geomorphic rejuvenation. The findings confirm the efficiency of integrated quantitative morphometric analysis in identifying tectonically active zones in mountainous regions and provide a useful framework for tectonic geomorphology and hazard assessment in the Central Alborz.

Keywords

References

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Environmental Management Hazards
Volume 12, Issue 4
January 2026
Pages 351-366

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