Low cost geotechnology applied to flood risk assessment in coastal urban areas in climate change scenarios

Abstract

The rise in average sea level and the trend of more occurrences of coastal flooding in the world are concerns of the international community. Understanding hazards, exposure and risks in coastal cities are important in planning and designing adaptation policies. The goal of this article was to model coastal flooding due to sea level rise in low and flat areas under the influence of tides that pose risks to the urban environment through Remotely Piloted Aircraft (RPA) and low-cost accuracy geodesy taking, as a case study, the city of Areia Branca in the state of Rio Grande do Norte (Northeastern Brazil). The flood modelling was carried out on a Digital Surface Model with vertical precision of 5.2 cm generated by digital photogrammetry techniques, and linked to the Brazilian Geodetic System from Global Navigation Satellite System (GNSS) data. The flood quota was converted based on the Reduction Level of the Navy and adjusted to an IBGE Reference Level. The analysis of the risks of coastal flooding in the city of Areia Branca/RN revealed a flood depth of 50 cm, reaching public and private areas, aggravated by the vulnerability of most of the population and by the occupation of areas affected by the highest spring tides. Flood events may result in damages of the order of R$ 597,438.68 or $ 147,152.37 ($ 1 = R$ 4.06 as of 09/1/2018), and climate change scenarios demonstrate flood trends that can affect approximately 40% of the city.