Fractal measures of drainage network to investigate surface deformation from remote sensing data: A paradigm from Hindukush (NE-Afghanistan)

Abstract

This approach represents the relative susceptibility of the topography of the earth to active deformation by means of geometrical distinctiveness of the river networks. This investigation employs the fractal analysis of drainage system extracted from ASTER Global Digital Elevation Model (GDEM-30m resolution). The objective is to mark active structures and to pinpoint the areas robustly influenced by neotectonics. This approach was examined in the Hindukush, NE-Afghanistan. This region is frequently affected by deadly earthquakes and the modern fault activities and deformation are driven by the collision between the northward-moving Indian subcontinent and Eurasia. This attempt is based on the fact that drainage system is strained to linearize due to neotectonic deformation. Hence, the low fractal dimensions of the Kabul, Panjsher, Laghman, Andarab, Alingar and Kocha Rivers are credited to active tectonics. A comprehensive textural examination is conducted to probe the linearization, heterogeneity and connectivity of the drainage patterns. The aspects for these natural textures are computed by using the fractal dimension (FD), lacunarity (LA) and succolarity (SA) approach. All these methods are naturally interrelated, i.e. objects with similar FD can be further differentiated with LA and/or SA analysis. The maps of FD, LA and SA values are generated by using a sliding window of 50 arc seconds by 50 arc seconds (50" × 50"). Afterwards, the maps are interpreted in terms of regional susceptibility to neotectonics. This method is useful to pinpoint numerous zones where the drainage system is highly controlled by Hindukush active structures. In the North-Northeast of the Kabul block, we recognized active tectonic blocks. The region comprising, Kabul, Panjsher, Andrab, Alingar and Badakhshan is more susceptible to damaging events. This investigation concludes that the fractal analysis of the river networks is a bonus tool to localize areas vulnerable to deadly incidents influencing the Earth's topography and consequently intimidate human lives.

Appraisal of active tectonics in Hindu Kush: Insights from DEM derived geomorphic indices and drainage analysis

“…The aim is to quantify the influence of neotectonic activity on the drainage network by measuring the reduction of complexity as the deformation intensity increases. This means that for a site highly vulnerable to neotectonic deformation, lower FD values should be obtained (Mahmood and Gloaguen, 2011). We expect that the drainage network looses its dendricity to become linearized as topographical changes triggered by faults modify the flow network geometry.…”

“…The space filling nature of the drainage network is a strong marker of the area vulnerable to tectonic deformation. The highly steepened regions cause the drainage network to reorganize and linearize which is an evidence of uplifted conditions (Mahmood and Gloaguen, 2011). In tectonically active Hindu Kush, drainage systems are influenced by the type, geometry and the recent activity of the regional and local faults.…”

“…In tectonically active Hindu Kush, drainage systems are influenced by the type, geometry and the recent activity of the regional and local faults. The FD quantifies the degree of irregularity or segmentation of an object or spatial pattern (Gloaguen et al, 2007;Mahmood and Gloaguen, 2011).…”

“…This investigation applies a quantitative analysis of geomorphic indices extracted from the digital elevation model (DEM) in Lawrence et al, 1981;Wheeler et al, 2005;Doebrich and Wahl, 2006;Mahmood and Gloaguen, 2011. Hindu Kush and its neighbourhood to evaluate relative active tectonics.…”

“…calculation and then took the mean of all the resultant values. The resulting mean Vf (0.31) for the Chitral valley belongs to class 1 which means that it is completely a V-shaped valley and is under the influence of neotectonic activity of the above mentioned fault zone(Keller and Pinter, 2002;Mahmood and Gloaguen, 2011). The basin shape index value is the highest for the Chitral valley (3.22) which means that this sub-basin is highly elongated in shape and is parallel to the topographic slope along the KoF-MKT-CGF-RF-TMF fault zone.…”