Reconstruction of Ice-Dammed Lake Outburst Floods in the Altai Mountains, Siberia - a Review

Seven independent approaches to estimate the Pleistocene ice-dammed lake outburst floods in the Altai- Mountains were applied. More detailed studies form the basis of this review. Different methods are briefly presented and discussed. The peak discharge is estimated as about 10,000,000 m³s¹. This estimate is based on three independent calculations, considering numerous locations with palaeostage indicators along the flood's pathway Run-up sediments are found in front of the local valley obstructions. Their characteristics and their relation to giant bars nearby is considered to calculate the velocity head of the flow, which is interpreted as indicator of the mean flow velocity Due to the dynamics of the investigated flood, related features, such as gravel dunes and obstacle marks, provide data on unspecified stages of the decreasing flood. An attempt to estimate peak discharge by using flow competence approach faded due to missing evidence of associated macroturbulence effects.

Compared with previous estimates the peak discharge calculated with several conservative assumptions seems to be smaller than expected. The new calculations are based on a significantly increased number of palaeostage indicators, which support the plausibility of the results.