Changes in Water Balance Elements in the Basins of the Largest Tributaries of Lake Baikal in the Late XX–Early XXI Century

Long-term variations in the water balance were analyzed in the basins of 20 largest tributaries of the Baikal. The values of river runoff were derived from actual data on the period from 1976 to 2019, and those of evaporation, precipitation, and potential evaporation, from ERA5-Land reanalysis since 1976 to 2020. Data were obtained to show an increase in the potential evaporation in all analyzed drainage basins by values from 0.39 to 0.62% per year since 1976 to 2020. A moderate or statistically insignificant decrease is typical of precipitation (0.25 to 0.59% per year) and water discharges, mostly due to a decrease in the summer runoff at a rate of 5.6%/10 years. The possible role of changes in vegetation cover in these processes was studied by evaluating NDVI parameter in 2019 compared with 2002 by data of space surveys MOD13A3 and MYD13A3 with MODIS spectroradiometer of Terra and Aqua satellites. A conclusion was made about the key role of precipitation in the decrease in the maximal runoff in Lake Baikal basin.