Climate related hazards: prevention, risk management, mitigation and forecasting

Much of this contribution to the symposium is written from the perspective of flood management but issues on risk management are common to natural hazards more broadly. Here we define a hazard as a situation that has the potential to cause harm. Hence we take an anthropocentric viewpoint (no humans, no hazards and certainly no risk). Hydro-meteorological hazards in their most generic form derive from precipitation, wind speed, thermal conditions and transport of air-borne pollutants and pathogens. Fluctuations in these quantities may occur over a wide range of temporal and spatial scales. Human life, society etc is generally well adapted to the status quo – the climatic average and “normal” variability; it is the variations beyond the normal that mainly give rise to the natural hazards such as: • floods (flash-floods, extensive floods of lowland plains, groundwater floods), • avalanche (snow / rock), • landslide, mud and debris flows – often in conjunction with floods • storm surge, storm wave leading to inundation of coasts and estuaries • windstorm and tornado • drought This contribution to the symposium concentrates on issues associated generally with short-term precipitation extremes at a variety of spatial scales. In flooding, the greatest risk to life occurs in unexpected flooding whether from flash flooding from rainfall or from large waves close to the shoreline. Heavy rainfall also can trigger land instabilities, with landslides posing a substantial risk to life and property in certain areas of Europe. Economic and property damage is often most severe for events with a large spatial scale – major basin floods or coastal surges. However, triggering mechanisms for floods can also depend upon longer term climatic conditions such as seasonal accumulations of snow or, for landslides, the season-scale accumulation of rainfall. The social and economic impacts of natural hazards are well documented elsewhere; see for example the recent report of the European Environment Agency (2003)