Análise histórica das enxurradas no município de Pelotas e as consequências da enxurrada de 2009 na Bacia Hidrográfica do Arroio Quilombo, Pelotas/ RS.

Abstract

This research addresses the consequences of heavy rainfall that occurred in Pelotas, which led to a great flash flood on the 28th and 29th January 2009. The area of research is the Quilombo Creek Watershed, Pelotas municipality, in the State of Rio Grande do Sul. Most of the Watershed is located in the rural zone of the Pelotas municipality, but also has a small section in the Canguçu municipality and another small section in the Arroio do Padre municipality. The time frame starts at the beginning of the twentieth century until 2009, when the flash flood hit the Quilombo Creek Watershed, leaving very significant consequences. Flash floods can be considered as a natural disaster, both for their intensity and their consequences. Thus, the theoretical background deals with the issue of natural disasters in order to understand some flood concepts that frequently create confusion in Portuguese: “enxurradas”, “enchentes”, “inundações” and “alagamentos”. This way the presented theoretical background tries to solve this confusion and other conceptual problems. This research has the following objectives: understand the factors that triggered the flash flood of the 28th and 29th January 2009 in the Quilombo Creek Watershed, as well as the consequent geomorphological changes; expose a theoretical background about natural disasters, geomorphology, geomorphological changes, land use and land cover, flashfloods and their consequences; carry out a historical review of the floods in the Pelotas municipality as well as a historical review of the floods in the Quilombo Creek Watershed; carry out a morphometrical study of the Quilombo Creek Watershed; observe the land use and land cover in the studied area; study the landscape changes and identify the damage done to the patrimony in the area of study after the 28th and 29th January flash flood. This research shows that the 2009 flash flood was not the only high intensity event to touch the Quilombo Creek Watershed. However, the studied watershed does not present natural conditions that would trigger flash floods, and the 2009 flash flood does not affect the entire Watershed in the same way. It intensely hit the lower part of the watershed creating consequences such as animal loss, land crop loss and material loss. The interviews showed that the most significant geomorphological changes occurred outside the boundaries of the studied watershed.