Characterization of displacement and internal structure of landslides from multitemporal UAV and ERT imaging
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Guruh Samodra I Muhammad Fauzan Ramadhan I Junun Sartohadi I Muhammad Anggri Setiawan I Nugroho Christanto I Adhera Sukmawijaya
Characterization of displacement and internal structure of landslides from multitemporal UAV and ERT imaging
Abstract Preliminary knowledge of the surface movement and internal structure of a landslide is essential to improve the understanding of landslide behavior as an initial step to develop suitable mitigation measures. This paper characterizes displacement and internal structure of landslides using multitemporal unmanned aerial vehicles (UAV) and electrical resistivity tomography (ERT) imaging. Multitemporal orthophotos, digital elevation model (DEM) profile lines, DEMs of difference (DoD), and ERT images allowed us to measure the landslide morphometry and areal changes, detect the trend of surface displacement, calculate the surface movement rate and direction, characterize the spatial variability in surface movement rates, and relate spatial variation in displacement to the internal structure of the landslide. The Kalisari Landslide experienced retrogressive movement where the scarp of landslide moved backward 38 m from 2015 to 2019. The surface movement ranged from 0.7 to 8.1 m with the direction mostly to the northeast. The depletion and accumulation ranged from 0.1 to 5 m, with the most active change located northwest of the landslide. The variability in movement was influenced by the spatial variability in the subsurface material inferred from the ERT images, i.e., surface material, clay, weathered breccias (possibly altered), and breccias. The interpretation from multitemporal UAV and ERT images indicates that the Kalisari Landslide has a nonhomogeneous multiple retrogressive behavior with a curved slip surface located at the clay layer. Keywords Displacement . Internal structure . Rotational . Multitemporal UAV . ERT Introduction The development of landslide mitigation technique that incorporates landslide investigation and monitoring is very important to reduce landslide risk. Landslide investigation and monitoring provide information on the type, cause, and potential development of slope movement. Various techniques have been developed to recognize and identify landslides such as terrain evaluation, mapping techniques, remote sensing techniques, and field reconnaissance techniques (Rib and Liang 1978). Preliminary landslide characterization, including the investigation of surface movement and internal structure, improves the understanding of landslide behavior and is the initial step in developing suitable mitigation procedure. Surface movement or landslide displacement is usually measured by using inclinometers (Calcaterra et al. 2012; Simeoni and Mongiovì 2007; Stark and Choi 2008; Zhang et al. 2018), GNSS or optical devices (Baldi et al. 2008; Benoit et al. 2015; Squarzoni et al. 2005), terrestrial laser scanning (Abellán et al. 2014; Barbarella et al. 2015; Teza et al. 2007), SAR interferometry (Monserrat et al. 2014; Raucoules et al. 2013), digital photogrammetry (Gonz
