ИСТИНА

For the majority of mountain glaciers around the world, recent decades have been characterized by an increasingly negative glacier mass balance, consequent glacier shrinkage and termini retreat attributed to rapid climatic warming. The process is typical for both China and Russia, where glacier covered area changed with an annual rate of more than -0.30% since the 1960s (Dyurgerov, 2010). Glacier retreat leads to various environmental consequences, including: (i) increase of mass movement activity on steep slopes due to destabilizing effect of glacier retreat/thinning; (ii) deposition of loose easily eroded debris in the valley bottoms; (iii) formation and expansion of glacier lakes. These consequences are responsible for debris flow formation, magnitude etc. It means that in glacier covered mountains we often meet situations without historical precedent and thus standard approach to debris flow hazard assessment based on frequency/magnitude/runout distance could be incorrect. Furthermore, to avoid errors in hazard assessment and prevent future damage and losses we have to take into account projected change in glacial and periglacial area. Using historical cases from Russian Caucasus and other glacier covered mountains we try to improve standard approaches of debris flow hazard assessment. We propose a scheme for glacier lake outburst probability assessment, develop a new technique to determine lake expansion limit and improve quality of input data required for numerical simulation. In this assessment, we use high resolution remote sensing imagery and data from field campaigns (lake bathymetry, glacier ice thickness measurements, logger data etc). We hope that our approaches, elaborated mostly in the Caucasus, can be applied for many glacier-covered mountain areas in China.