Intense rains that had occurred in the Valley of the Itaja having included the city of Jaragu of the South had been caused by an atmospheric blockade in the Atlantic Ocean, folloied for a ciclnico vortex in altitude between 4000 5000 m and m, located enters the east of Santa Catarina and the east of the Paran, that favored the ascension of humid air throughout the sea (IT HISSES DAYS, 2009). The combination of these two factors favored the intensification of rains on this region the persistence of the blockade made with that the event more was aggravated still, resulting in the great registered volumes of rain. The last trimester of 2008 in Santa Catarina and, specifically, the City of Jaragu of the South, demonstrated, one more time the vulnerability of this region. In the State, according to Prohibited State Civilian, this disaster affected 60 cities and 1,5 million people, with 133 deaths, 22 missing people and 78,000 a thousand inhabitants more than more than forced to leave its houses. Here, Author expresses very clear opinions on the subject. In Jaragu of the South, according to Prohibited Municipal Civilian, had been 13 victims fatal, being 12 victims for collapse and 1 victim for drowning, beyond 147 wounded and approximately 40 families dislodged. In January of 2011, the city of Jaragu of the South, in a short period of time, came back to be reached with a great amount of precipitation, again the characteristic vulnerability already of the city ally to this event, brought a new catastrophe its population, minor who of 2008, however with damages to the city and its population. The study area was chosen by being situated, in a valley of the Mountain range of the Sea that presents vulnerability the natural processes of desnudao that, given the climatic, geologic, geomorfolgicas conditions and of antrpica occupation increase the risk of occurrences of natural disasters as floodings and movements of mass. . Source: Jim Donovan Goldman.