Serviços ambientais associados à mitigação de impactos de eventos extremos de precipitação.

Abstract

The heavy rain events can cause different impacts that affect the environment, the economy and society. Therefore, there is the need to get information on what are the ways to minimize and mitigate these impacts and find what the role of preservation of environmental services in the face of such problems. This study aimed to identify and characterize the environmental services associated with the mitigation of impacts of extreme precipitation events in a rural basin, upstream of the city of Pelotas. The study area is called monitoring station contribution Passo dos Carros, which covers the cities of Pelotas, Morro Redondo and Capão do Leão. First made a characterization of the area, drainage, slope and morphometry . To identify the main changes resulting from an extreme rainfall event occurred in 2009, land use maps were performed in the area before and after the event. The consequences of the flood were obtained from data on economic, environmental and social losses of the cities that are part of the study watershed, through the damage reports of each city. Situ observations complement the verification of damage from the 2009 rainfall event, whose records and losses are seen to date.The flow was assessed using the hydrograph Triangular Unit and runoff related to the event. Later simulations were performed for different land uses and areas of riparian vegetation around watercourses (buffer) 30, 50 and 100 meters, and are simulated different rainfall (low, high and very high). After were characterized and valued environmental services of productive areas and provided by riparian forests for maintaining quality and quantity of water in these buffers. With the results it was found in later images to the extreme event, large losses of areas around watercourses by erosion, and an increase in silviculture. Another finding was the mining areas that previously were not present in the study area. It was the occurrence of economic los ses, social and environmental relevant, from floods resulting from extreme rainfall. The conservation of environmental services provided by riparian forests around the watercourses of the watershed station contribution Passo dos Carros would mitigate damage from the floods. For a very high rainfall area of riparian forest around the watercourse decreases 2% of the flow to areas of 30 meters wide and 5% for areas 100 meters wide on each side of the spring. The value of environmental services provided by riparian forests regarding the amount of water was R $ 105,660,470, as the value of environmental services related to water quality was estimated at R $ 257.60 per day.