Keywords: bank erosion – landslide - remote sensing – TLS –
UAV
Abstract. The study object is the Kuibyshev reservoir (Volga
River basin, Russia) – the largest in Eurasia and the third in the
world by area (6150 km2). The objective is to
quantitatively assess reservoir bank landslides and shoreline abrasion
in active zones based on the integrated use of modern instrumental
methods (i.e. terrestrial laser scanning, unmanned aerial vehicle,
remote sensing and a global navigation satellite system). A methodology
for the application of different methods of instrumental assessment of
abrasion and landslide processes is given. Different approaches are used
to assess the intensity of landslide and abrasion processes: the
specific volume and material loss index, the planar displacement of the
bank scarp, and the planar-altitude analysis of displaced soil masses
based on the analysis of slope profiles. Shoreline position for the past
periods (1958, 1985, and 1987) was obtained from archival aerial photo
data; whereas data for 1975, 1993, 2010, 2011, and 2012 were obtained
from high-resolution satellite image interpretation. Field surveys of
these geomorphic processes at the study areas in 2002, 2003, 2005, 2006,
2014 were carried out using Trimble M3 and Trimble VX total stations
(2014); in 2012-2014 using terrestrial laser scanning and a UAV survey
in 2019. The monitoring of landslide processes showed that the rate of
volumetric changes at Site 1 remained rather stable during the
measurement period with net material losses of 0.03-0.04
m3/m2/year. The most significant
contribution to the average annual value of material loss was by
snowmelt runoff. The landslide scarp retreat rate at Site 2 showed a
steady decreasing trend, due to partial overgrowth of the landslide
accumulation zone resulting in its relative stabilization. The average
long-term landslide scarp retreat rate is 2.3 m/year. In recent years,
landslide control measures realized at this site have reduced the
landsliding intensity by more than 2.5 times to 0.84 m/year.