Characterization of an Unstable Slope Using Geophysical, UAV, and Geological Techniques: Karakoram Himalaya, Northern Pakistan

Abstract

Given active tectonism, rough terrain, and climate, the mountainous ranges in northern Pakistan are prone to geohazards, including earthquakes, unstable slopes, and landslides. The frequent landsliding in the region poses a risk to communities, economic activities, and transportation networks. In this context, the unstable slope above Mayun village calls for a multi-method approach for better assessment of the slope for planning interventions aimed at hazard mitigation. We conducted an integrated study including uncrewed aerial vehicle (UAV) and ground-penetrating radar (GPR) in coordination with geomorphic field observations to image the possible slip surfaces for a comprehensive understanding of a potential future rockslide with significant socioeconomic consequences. UAV-derived results helped delineate the overall extent of the unstable slope and its downslope area in a quick, remote, and safe way. GPR profiles have enabled the reconstruction of the bedrock’s morphology and its internal structure and the depth distribution of cracks running through the overburden and bedrock. The results provided insight into the stable and unstable compartments of the slope due to the thin cover of surficial deposits, high impedance contrast at the overburden-bedrock interface, lateral heterogeneities, and presence of open cracks, and almost detached blocks, respectively. These data on the dynamic properties of a landslide-prone slope could be used for the correct planning of civil infrastructure to minimize the potential risk of building damage in the seismically active Hunza valley.

Geophysical and Geochemical Characterization of Solidwaste Dumpsite: A Case Study of Chowa Gujar, Peshawar (Part of Indus Basin)

“…GPR signal dies out as it interacts with a highly conductive contaminated body, therefore no reflection is observed below the signal attenuation zone [46]. A similar pattern of subsurface contamination generated by dumpsites was also observed by [37,47,48]. In the current study, some diffraction signals are observed towards the agricultural landside, which could be due to uncontaminated land.…”

“…GPR signal dies out as it interacts with a highly conductive contaminated body, therefore no reflection is observed below the signal attenuation zone [46]. A similar pattern of subsurface contamination generated by dumpsites was also observed by [37,47,48].…”

“…Ground Penetrating Radar emits high-frequency electromagnetic waves (1 MHz to 1000 MHz) [35]. GPR method has been applied to a variety of problems such as detection of voids in the subsurface and geological layer boundaries, location of installations, and archaeological and forensics studies [36,37]. The GPR applications to monitor landfill have been discussed by [38].…”

Combined ERT and GPR Data for Subsurface Characterization of Weathered Hilly Slope: A Case Study in Zhejiang Province, Southeast China

“…By analyzing the reflected signal of transmitted waves from the interface where there is a difference in materials, the GPR technique can image shallow subsurface structures (even small cavities) and determine the distance at which they are located. Since the 1980s, GPR has been increasingly accepted for the localization of fractures or cracks [14][15][16][17][18], the identification of stratigraphy or shear deformation [19][20][21][22][23], and the characterization of soil water variations [24][25][26][27] in the geological, environmental, and engineering areas. However, the transmitted waves of GPR are strongly attenuated in conductive zones (e.g., water-rich, clay-rich) and cannot penetrate at greater depths to identify unknown objects of interest.…”

Geomorphological processes and their connectivity in hillslope, fluvial, and coastal areas in Bangladesh: A review

“…Therefore, integrated regional research or basin-wide studies are required for comprehensive understanding of the fluvial processes and sediment dispersal mechanisms from upstream to downstream GBM concerning Bangladesh. In particular, the advanced remote sensing techniques (such as UAS imagery, LiDAR) for geomorphological research, which are encouragingly used in neighboring countries like China (LeHeron et al 2019), India(Ramsankaran et al 2020;Dhote et al 2022), Bhutan(Dunning et al 2009;Tempa et al 2021), Nepal(Immerzeel et al 2014;Kraaijenbrink et al 2016;Van Woerkom et al 2019), Pakistan(Khan et al 2021), and in other parts of the worlds(Śledź et al 2021), will improve the understandings of landscape evolution and fluvial dynamics not only in the upper Ganges-Brahmaputra but also the entire watershed scale including the downstream reaches in Bangladesh.…”