The man then generates ambient impacts, that is, indesejadas consequences or that they compromise the balance and the existing state of an environment, in virtue of the type, the intensity and the speed to promote changes by means of its activities. Many times, are enough to look at the conditions where if it finds a territory, the types, the structure and the form of handling of the activities human beings who easily we lead the interpretation of the existing impacts. Flooding, landslide, estiagem, etc., are natural phenomena, observed frequently in the nature. When these phenomena occur in places where the human being acts, as, for example, in cities, next the villages or houses, them they provoke material and human damages to the society. In this case is treated as natural disasters. Moreover, the global heating increases the frequency and the intensity of rain events, contributing in the increase of the incidence of natural disasters.

They are examples of natural disasters: floodings, landslides (or slippings), volcanic estiagem, eruptions, hurricanes, gales, hail, forest fire, earthquakes, rays, and storms (KOBIYAMA, at. al., 2006). The natural disasters can be appraised, of form simplified, as the result of the impact of an extreme or intense natural phenomenon on a social system, causing serious damages and damages that the capacity of the affected ones exceeds coexisting impact (TOBIN and MONTZ, 1997; UNDP, 2004). The natural disasters, as a whole, are distinguished mainly in function of its origin, that is, of the nature of the phenomenon unchained that it. In agreement with the normative ones of the National Politics of Civil Defense, three types of disasters exist: natural, human and mixing (I CASTRATE, 1998). In accordance with Quarantelli (1998), a disaster is an event concentrated in the time and the space, in which a community tries severe danger and destruction of its essential services, folloied for dispersion material and ambient human being, losses, that frequently exceed the capacity of this community dealing with the consequences of the disaster without the external aid.