QUANTITATIVE ASSESSMENT OF GLACIAL DEBRIS FLOW HAZARD IN ILE ALATAU

The present publication is devoted to studying the problem of quantitatively assessing glacial debris flow hazards. The study area, which includes river basins in the central part of the northern slope of Ile Alatau, is characterized by increased debris flow activity. Currently existing methods of glacial debris flow hazard assessment are based mainly on qualitative criteria. Despite the fact that such assessments were generally based on the results of field surveys and observations, their outcomes were largely determined by subjective factors. The aim of the study is to address the problem of using quantitative criteria in assessing the outburst hazard of moraine-glacial lakes by creating a new methodology for the quantitative assessment of glacial debris flow hazards based on empirical data. The geodetic and bathymetric measurements of lake basins located on modern moraines and directly at glacier tongues served as a basis for this work, allowing us to identify relationships between lake areas and volumes. This paper presents the results of glacial debris flow hazard assessment, largely obtained for the first time using a computational method, for the most studied debris flow-prone areas of Ile Alatau. For the quantitative assessment of glacial debris flow hazard, the results of direct observations of moraine-glacial lake outbursts were used, allowing us to obtain quantitative characteristics and hydrographs of outburst floods. The relationships between the volumes of outburst floods and the maximum discharge of turbulent mudstone flows at the outlet of debris flow centers (incisions), measured by the instrumental method and using empirical calculation formulas, were also identified. These data were obtained during special surveys of the traces of past debris flows