Contribution of Natural and Anthropogenic Aspects for the Analysis of Flood Hazard in Campinas- SP

Abstract

Floods are natural phenomena, which can cause environmental impact according to land cover and use changes, due to demographic intensification and urban growth. Therefore, this study aimed to include the relationship between natural and anthropogenic systems into the elaboration of models for the analysis of flood hazard. Flood hazard models were generated using weighted overlay method and multicriterial Analytic Hierarchy Process (AHP), considering the following parameters: elevation, drainage density, slope, rainfall, soils, natural vegetation cover and land use and land cover for the dates 1975 and 2018. The classes of land use and cover (urban, agricultural land, bare soil, arboreal cover, grasslands, water and others) were classified by region method from LANDSAT images and the maximum likelihood classifier. It was observed that High and Very High classes changed when natural and anthropogenic hazard floods models for 1975 and 2018 were compared regarding area extension, which growth to 225.7km² (28.63%) and 26.59km² (3,37%) in 1975, and 260.97km² (33.09%) and 22.88km² (2.90%) in 2018. These alterations for High hazard area were larger for the basins of Rio Capivari changing 34.3km² (1975) and 56.8km² (2018), Ribeirão Anhumas changing 28.4km² (1975) and 35.4km² (2018), Ribeirão Quilombo changing 14.1km² (1975) and 22.8km² (2018), and Rio Atibaia changing 20.6km² (1975) and 13.4km² (2018). The variation in the high risk of flooding in these basins is attributed to population density and soil impermeability as a result of urban expansion in areas of river plains, which alter the flow and infiltration of surface waters.