Impact of the global climate change on the transboundary Selenga River water runoff and general principles of its water resources use by Endon Zh. Garmaev, Andrey V. Khristoforov, Bair Z. Tsydypov, Alexander A. Ayurzhanaev, Sergey G. Andreev, Bator V. Sodnomov, Daba Ts.-D. Zhamyanov