How does the suspended sediment yield change in the North Caucasus
during the Anthropocene?
Abstract
Quantifying and understanding catchment sediment yields is crucial both
from a scientific and environmental management perspective. To deepen
the understanding of land use impacts and climate change on sediment
load, we explore mechanisms of the suspended sediment yield formation in
the Northern Caucasus during the Anthropocene. We examine how sediment
flux of various river basins with different land-use/landcover and
glacier cover changes during the 1925-2018 period. Our analysis is based
on observed mean annual suspended sediment discharges (SSD, kg·s−1) and
annual fluxes (SSL, t·yr−1) from 33 Roshydromet gauging stations
(Russia). SSL series have been analyzed to detect statistically
significant changes during the 1925-2018 period. The occurrence of
abrupt change points in SSD was investigated using cumulative sum
(CUSUM) charts. We found that SSL has decreased by −1.81% per year on
average at most gauges. However, the decline was not linear. Several
transition years are expected in the region: increasing trends from the
1950s and decreasing trends from 1988-1994. Correlation analyses showed
that variation in SSL trend values is mainly explained by gauging
station altitude, differences in land use (i.e., the fraction of
cropland), and catchment area. Nonetheless, more accurate
quantifications of SSL trend values and more refined characterizations
of the catchments regarding (historical) land use, soil types/lithology,
weather conditions, and topography may reveal other tendencies.