Identification of potentially dangerous glacial lakes in the northern Tien Shan

Like in many other parts of the world, the glaciers in northern Tien Shan are receding, and the permafrost is thawing. Concomitantly, glacial lakes are developing. Historically, outbursts of these glacial lakes have resulted in severe hazards for infrastructures and livelihood. Multi-temporal space imageries are an ideal means to study and monitor glaciers and glacial lakes over large areas. Geomorphometric analysis and modelling allows to estimate the potential danger for glacial lake outburst floods (GLOFs). This paper presents a comprehensive approach by coupling of remote sensing, geomorphometric analyses aided with GIS modelling for the identification of potentially dangerous glacial lakes. We suggest a classification scheme based on an additive ratio scale in order to prioritise sites for detailed investigations. The identification and monitoring of glacial lakes was carried out semi-automatically using band ratioing and the normalised difference water index (NDWI) based on multi-temporal space imagery from the years 1971 to 2008 using Corona, ASTER and Landsat data. The results were manually edited when required. The probability of the growth of a glacial lake was estimated by analysing glacier changes, glacier motion and slope analysis. A permafrost model was developed based on geomorphometric parameters, solar radiation and regionalised temperature conditions which permitted to assess the influence of potential permafrost thawing. Finally, a GIS-based model was applied to simulate the possibly affected area of lake outbursts. The findings of this study indicate an increasing number and area of glacial lakes in the northern Tien Shan region. We identified several lakes with a medium to high potential for an outburst after a classification according to their outburst probability and their downstream impact. These lakes should be investigated more in detail

A risk society? Environmental hazards, risk and resilience in the later Middle Ages in Europe

Modern society is said to have restructured in reaction to contemporary hazards with the aim of improving its management of risk. This implies that pre-industrial societies were somehow fundamentally different. In this paper, we challenge that hypothesis by examining the ways in which risks associated with environmental hazards were managed and mitigated during the Middle Ages (defined here as the period from 1000 to 1550 AD). Beginning with a review of the many case studies of rapid onset disasters across Europe, we draw upon both historical and archaeological evidence and architectural assessments of structural damage for what is a pre-instrumental period. Building upon this, the second part of the paper explores individual outlooks on risk, emphasising the diversity of popular belief and the central importance of Christianity in framing attitudes. Despite their religious perspectives, we find that medieval communities were not helpless in the face of serious environmental hazards. We argue instead that the response of society to these threats was frequently complex, considered and, at times, surprisingly modern