Drought events

Part of the concern about global climate change stems from the human tendency to seek meaniiig in events that may or may not be more than simply a random event. A particularly cold winter, a particularly hot summer, an especially rainy season, or an especially severe drought will all send people off on a search for the greater meaning of the phenomenon. Is it a pattern, or a one-time event Must we build a dike, or has the danger passed Since the summer of... 

Obviously, one looks for causes. That declines in one or another species have natural factor etiologies is unequivocal. The demise of American elms and of the chestnut were due to natural factors. Insect infestations, bacterial and fungal diseases, hurricanes, floods, freezes, droughts and many other stresses can cause extensive tree death (5). But in such declines typically only a single species is affected or climatic events caused decline in a delimited area. In almost all declines caused by natural events, the causal factors can be identified we know their precise etiologies. Natural events are always part of the natural environment and must be factored in when evaluating forest declines (Table I). 

Estrela T et al (2001) Sustainable water use in Europe. Part 3 Extreme hydrological events floods and droughts. European Environmental Agency, Copenhagen... 

However, the laws and regulatory programmes regarding water quality cope with most of the problems and legislation generally protects the population in developed countries, even when scarcity forces the use of non-conventional water resources. Outbreaks of water-borne diseases in these countries are more linked to intense rainfall events, mostly to those that follow drought periods, rather than to drought itself [1 ]. 

Genetically engineered traits are being introduced into new crops (e.g. alfalfa and strawberries) and new GM events (traits), which may have a greater impact on human health (e.g. pharmaceutical traits) and the environment (e.g. drought tolerance and plant made industrial products) are being developed. 

Before the first World Trade Center bombing in 1993 and the 1995 Oklahoma City bombing, emergency incidents were primarily or generally thought to be caused by natural or accidental events. Examples of natural phenomena (events) include wildfires, flash floods, earthquakes, active volcanoes, droughts, and storms. These natural events are not entirely predictable, and they cannot yet be controlled or prevented (Meyer 2004). 

The contribution of hydropower stations to energy production in Brazil in 2002 constituted 85%. Planning a hydropower system foresaw an event of three successive drought years. However, in April 2001 the volume of water in reservoirs of hydropower stations constituted only 20%-30% compared with the maximum. It is this that forced the Brazilian government to seriously limit energy consumption. 

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