4.4 Uncertainties
Among the uncertainty sources discussed in the corresponding section
(section 2.6), we suppose that uncertainty in trend results is mainly
attributed to data limitations. As suggested by previous studies (e.g.,
Onyutha, 2016), the uncertainty in the trend reduces as the series
record length increases. These difficulties may be to some extent be
solved by considering extended suspended sediment time series. However,
it can be impossible for gauging stations in the Terek basin as many
closed or stopped to measure suspended sediment yield. Likewise, future
research may still benefit from considering a larger number of
catchments from neighboring regions of the Greater Caucasus (e.g.,
Georgia, Armenia, Azerbaijan).
Even though we used data from 33 catchments (Fig. 1 ), which is
significantly more than many other contemporary studies in that region
(Gusarov et al. , 2021), this number may still be too small to
identify the impact of all relevant factors. However, especially
considering more high-altitude gauging stations (higher than 1000 m) in
the analyses could help since that altitude group is less populated with
prolonged timeseries.
Furthermore, apart from potential cropland, no other factors could be
identified that significantly correlated with the SSL trend in
high-mountain gauging stations (Fig. 8c ). In other words, our
analyses provide no evidence that SSL trend values for high
mountain catchments (with a gauging station altitude higher than 1000 m)
depend on landuse/landcover or spatial scale. However, it should be
emphasized that this does not necessarily imply that these factors
cannot influence the SSL change. The lack of significant
correlations between SSL trend values and the considered
variables may also be attributed to the inherent limitations of our
approach and a small number of gauging stations in this altitude group
subset.