Photogrammetry for early recognition of high mountain hazards: New techniques and applications

Steady mass shift as well as catastrophic mass-movement events are the natural expression of the dynamics of high-mountain mass-transport systems, causing a variety of natural hazards. Computer-aided aerial photogrammetry, especially a newly developed technique for determining surface velocity fields in 3D, offers a wide range of possibilities to map disasters and hazard potentials, to monitor medium- and long-term development of dangerous situations and to provide area-wide boundary conditions for 2D- and SD-modelling of kinetic and dynamic processes. Three pilot studies in the Swiss Alps illustrate the potential of high-precision and multi-temporal image analysis for early recognition of glacial and periglacial hazards: (1) The increasing risk of lake-outbursts and related debris-flows (up to several 10(5)m(3)) was detected by a 25-year monitoring series of glacier geometry, ice flow, permafrost creep and changes of glacier-lakes. (2) Analyzing permafrost creep above a potential starting zone of debris flows allowed for assessing mass transport and accumulation rates in this zone. (3) The kinetic processes and the extent of a rock slide (similar to 10(6) - 10(7)m(3)), induced by a marked retreat of a glacier tongue and the related stress-relief at the valley flanks could be determined. (C) 2000 Elsevier Science Ltd. All rights reserved.