Avaliação do risco de desastres por inundação no município de Barreiros, Pernambuco, Brasil

Abstract

Flood disasters are frequent in Brazil, and there are, many times, due to the high social vulnerability of the population living on the banks of rivers that cross urban centers. Barreiros, a municipality located on the coast of Pernambuco State, stands out for periodically suffering from these events, affecting the riverside population and many inhabitants, losing their assets. This study aims to evaluate the vulnerability of the population resident in areas prone to the risk of disasters due to urban flooding in the municipality of Barreiros, Pernambuco State. To indicate the areas susceptible to flooding, it was the terrain descriptor model, Height Above the Nearest Drainage (HAND), developed by the National Institute for Space Research (INPE, in Portuguese), which requires the Digital Elevation Model (DEM) as an input data. The spatial resolutions of the DEMs of the Alos satellite mission with the Palsar radar sensor, of 12.5 m x 12.5 m, were compared to the laser remote sensor LiDAR, of 1.0 m x 1.0 m (resampled to 5.0 m x 5.0 m). Historical flood events were recorded based on field visits, with the support of the Municipal Coordination of Protection and Civil Defense of Barreiros (COMPDEC/Barreiros, in Portuguese) and interviews with social actors residing in the nearby rivers of the urban area of the municipality and that served for the socioeconomic study of the inhabitants most affected for the recurrent floods. The floodable areas were divided into susceptibility classes (low, medium and high) using the HAND model and compared with the event map that occurred in 2017, available by the Pernambuco Water and Climate Agency (APAC, in Portuguese). The results were validated through the assertiveness statistics analysis of the so-called flooded and non-flooded points to verify the efficiency of the modeling. Then, maps of land use and occupation, presence of Permanent Preservation Areas (PPAs), slope, and home comfort were created, forming the map of Suitability for Housing. As main results, they were identified as areas of high, medium, and low susceptibility to flooding in the study area, with 72.6% of assertiveness of the flooded patch concerning the control points. Regarding the 2017 APAC flood patch, the HAND model reached an overlap of 89.7%. The distribution of people from areas most identified by the 2017 flood represented 66.2% of the control points in irregular areas such as PPAs in the urban area. Through the interviews, it was verified that the most vulnerable population presents low instruction level, the low family income people understand that they live in a risk condition and even, so they are satisfied with the place where they live. Based on the Housing Suitability map, the locations suitable for the relocation of residents, who live in PPAs and in areas indicated as being highly susceptible to flooding, were determined. It was also indicated that areas future vacated could serve the population, such as the creation of parks to encourage leisure and the sale of local handicrafts and the revitalization of PPAs as a work of environmental education with the population of Barreiros Municipality.