Sediment Load Runoff of Lake Baikal Tributaries: Changes and Trends

Abstract

t. Since the second half of the 1970s, rivers flowing into Lake Baikal have been experiencing a tendency to the sediment load reduce against the background of the global warming and various human activity in river basins. Integrated analysis of changes in hydro-meteorological parameters) and their trends over the period 1941–1975 (baseline) and 1976–2020 (warming) is performed. Changes in natural processes and human activity were negligible during the baseline period. In 1976–2020, the flow of sediment load in tributaries decreased by 53–80 % and changes occurred in its regime, which manifested itself in a decrease in its average and maximum indicators. The largest decrease in sediment load runoff was established in the last decades of the warming period. The average values of runoff in these decades are lower than the average value for the entire observation period by 1,5–3 times and by 3-5 times in comparison with the baseline period. Sediment runoff in the last decades corresponds to their modern export from tributaries to Lake Baikal and is 713∙103 t y−1 for Selenga, 85∙103 t y−1 for Upper Angara, 44∙103 t y−1 for Barguzin, 9,4∙103 t y−1 for Utulik and 7,9∙103 t y−1 for Hara-Murin. The results of the research are important for the study of processes related to lithodynamics, sedimentology, biogeochemistry, ecology in the system “Rivers – Lake Baikal” and contributes to the protection and rational management of the water resources of the lake.