Assessment of modern shoreline transformation rates on the banks of one of the largest reservoirs in the world (Kuibyshev reservoir, Russia) using instrumental methods

Abstract

The study object is the Kuibyshev reservoir. The objective is to quantitatively assess reservoir bank landslides and shoreline abrasion in active zones based on the integrated use of modern instrumental methods. 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 displacements of soil masses based on the analysis of slope profiles. Shoreline position for the past periods (1958, 1985, and 1987) was obtained from archival aerial photography data; 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 total stations; 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