DEM BASED COMPUTATION OF TOPOGRAPHIC SURFACE ROUGHNESS TO REVEAL INCISION IN GILGIT-BALTISTAN,PAKISTAN

Abstract

This research investigates interrelationship between landscape evolution and neotectonics in the Gilgit-Baltistan (GB) region based on surface roughness (SR). We analyzed the topographic surface features such as flat area, surface area and surface ratio using Shuttle RadaTopographic Mission-Digital Elevation Model (SRTM DEM) with a spatial resolution of 90 meters. The objective is to make a SR map and to identify areas influenced by neotectonics. The DEM based spatial distribution of slope gradients and slope orientations along with the aspect map were combined to portray the vertical dissection. Lower values of vertical dissection indicate relatively flat topographic basins which generally mean a region of with intermediate slope gradient and slope orientation. Areas with high vertical dissection values correspond to sharp changes in the slope gradients and slope orientations, which could be due to abrupt scrap edges (possibly neotectonic or lithological control). Higher vertical dissection values in GB are wide spread and are oriented SE- NW in Ghanche, Skardu, Hunza, Gilgit and northern Ghizer districts along Karakorum, South Pamirs and Hindu-Kush ranges. While a few higher roughness values are aligned NE- SW in Diamir and Gilgit districts along the Raikot Fault. The surface roughness map is capable of identifying deeply incised valleys, tectonic uplifts and depressions.