EGS XXVI General Assembly, Nice, France, March 2001

ERE5. Anthropogenic influences on the scale and frequency of natural disasters (co-sponsored by NH):

Event Information

Ever since the beginning of civilisation natural hazards have affected mankind, and mankind has had to learn to deal with dangers and disasters at all scales from local landslides to potentially catastrophic global climate events. Commonly such disasters are considered to be part of living on a dynamic planet and outside the influence of human activities. However, now important questions need to be raised concerning how human activities may influence some forms of natural hazards, making loss of life more likely in the future. This question arise, for instance, about the possibility of (i) increased rainfall and flooding events, (ii) sea-level rise and associated inundation of fertile inhabited coastal strips and islands, (iii) increased occurrence of landslides resulting from increased precipitation, (iv) increased severity of droughts and occurrence of droughts in larger latitudinal zones, (v) increased meteorological hazards such as hurricanes and typhoons, and (vi) destabilisation of historically stable snow and ice fields leading to avalanches, as is beginning to occur in the Alps. A conclusion of some recent international meetings, point out the increase in damages due to natural hazards in recent years. However, no definitive conclusion about the impact of climatic change on natural hazards can be made at the moment. The human impact of natural disasters is partly related to the probability of natural hazards occurring, and partly related to vulnerability, which depends directly of the human behaviour in the risk prone areas. Consequently, the anthropogenic influences on natural disasters has to be analysed taking into account human impact on the hazard itself and changes in human behaviour that affect their vulnerability. This field concerns present activities of UNESCO International Hydrological Programme, like FRIEND or HELP, and also future Sixth Phase of the IHP (2002-2007). The study of human impact on environment requires analysis at medium or large-scale. Medium-scale human activities can be analysed, such as sequences of social patterns in which vulnerability in response to natural hazards is variable and changing. In different epochs and different geographical sectors, the human response to natural catastrophic events has also been different. The record of all these experiences can be studied to develop useful management strategies not only for local-regional scale problems, but also for global-scale worst-case environmental scenarios. In the medium time scale, changes in the frequency or intensity of natural hazards is not as important as changes in the vulnerability level of human communities. Usually these changes are produced by negative intervention of human communities at different scales. Examples include (i) artificial changes in river-bed conditions that increase the flood frequency factor, (ii) erosive and land-slide processes resulting from local or regional land-use changes, (iii) water resources management and man-induced water shortages, and (iv) microclimatic changes produced by air pollution in urban sectors. All such events are the subject of much scientific research, and our growing knowledge is being used to help minimise risk through the use of coastal defences, managed river networks, storm forecasting, global emergency responses, and the avoidance of development in areas of known high risk. However, increased occurrence and severity of natural hazards as a result of human influence may outstrip our ability to understand and manage them. Presentations in this session are invited on the broad scope of this subject, outlined above, including observation of natural hazards, the understanding of their processes, their impact in different socio-economic patterns, and the characterisation of the human role in the magnitude and temporal/spatial distribution of the final effects.

Preliminary List of Solicited Speakers

Co-Sponsorship