Влияние изменения климатических параметров на сток рек бассейна Байкала во второй половине XX – начале XXI вв.

The results of the analysis of 1950–2016 runoff changes of the Baikal Lake largest tributaries, namely the Selenga, Verkhnyaya Angara, Barguzin, Turka, Khara-Murin, Snezhnaya, Utulik and Bolshaya Rechka rivers, are presented. The influence of changing precipitation rate (P) and potential evapotranspiration (PET) on the changes in annual river runoff (R) for 1976–1995 and 1996–2016 compared to 1950–1975 is considered basing on the CRU TS data. The ECOMAG model was used to evaluate the R reproducing accuracy with various modifications of the Budyko formula using P and PET data. It was found that the difference between the R value calculated according to a formula and the modeled one is from 0,2 mm to 0,53 mm in the Selenga River basin with the P anomaly from –10% to +10%. It is shown that during 1950– 2016 the Baikal Lake basin as a whole is characterized by the decrease in P and R and the increase in PET. Deviation of calculated R values from observed ones for 1976–1995 and 1996–2016 was interpreted as an influence of other factors, which include both the properties of the underlying surface and specific features of the intra-annual distribution of precipitation and potential evapotranspiration. The role of other factors in the change of R varies depending on the catchment and period under consideration. It is shown that P and E changes during 1950–2016 explain about 50% of the R change in the Baikal Lake basin. Susceptibility of river runoff in the Baikal Lake basin to factors other than P and PET must be taken into account while assessing the scenarios of runoff changes of the Baikal rivers under climate change. It was also revealed that in 1976–1995 (except for the Khara-Murin River) and in 1996–2016 (except for the Khara-Murin and Selenga rivers) the runoff formation conditions were more favorable than in 1950–1975.