1.1.2 Ground-based laser scanning
Compared with traditional methods (aerial photography, ground photogrammetric survey, field studies), laser scanning has several advantages. Very precise results make it possible to estimate the intensity of slope processes, and estimate the age of landslide bodies (Monserrat & Crosetto, 2008; Dunning et al. , 2009), to build detailed three-dimensional models and evaluate the slope stability (Viero et al. , 2010). One of the essential uses of ground-based laser scanning is to study the dynamics of slope processes. The study of relief dynamics requires repeated measurements of the object under study and their comparison with previous data, which requires geodetically accurate referencing provided by modern ground-based laser scanning technologies (Barbarella et al. , 2015; Gafurov et al. , 2016; Yermolaev et al. , 2018).
Fundamentally different technology for scanning results of georeferencing was proposed in 2014 by a group of Polish researchers. A network of ground control points was organized with the use of the differential global positioning system (DGPS) (Kociuba et al. , 2014). The georeference accuracy, taking into account the DGPS receiver error, was 26 cm. In 2015, the same research team carried out laser scanning to monitor gully processes in a relative coordinate system, which led to an increase in the accuracy of scans adjustment by two orders (Kociuba et al. , 2015). Similar studies were carried out in 2008-2010 in Spain by the Jimenez-Peralvarez scientific team (Palenzuela et al. , 2016) and by Swiss scientists under the leadership of M. Franz in 2012 (Franz et al. , 2016). The combination of different technologies made it possible to achieve georeferencing accuracy within 11 mm in plan and 17 mm in height.
Studies of landslides near water bodies are mainly carried out on the coasts of seas and oceans (Spreafico et al. , 2015). Few scientific studies have been devoted to the monitoring of hazardous processes on slopes bordering reservoirs. Several publications on the Three Gorges Reservoir in China, created in 2003, stand out (Wanget al. , 2015; Nicu et al. , 2019; Zhang et al. , 2020; Guo et al. , 2020). In contrast, in Russia, there are many studies devoted to studying geomorphic processes on the banks of large reservoirs, because of the large-scale construction of hydroelectric power plants in the middle of the last century (Starodubtsev, 2012; Babicheva & Rzetala, 2013; Kalinin et al. , 2015; Bondur et al. , 2019; Mazaeva et al. , 2019; Nikonorova et al. , 2019).