Cenários de projeção do risco a inundações no estado da Paraíba.

Abstract

There is a tendency for flooding to increase due to constant changes in land use and occupation, climate change, and socioeconomic factors, which cause water insecurity in many world regions. In this sense, this research aimed to generate flood risk projections throughout the state of Paraíba considering global climate models from CMIP6 (Coupled Model Intercomparison Project Phase 6), socioeconomic model, and dynamic modeling of land use and cover, through the Dinamica EGO software, integrated to the GIS-MCA approach. The methodological approach proceeded under two time periods: the reference period (1970-2000) and the future period (2021-2040). Thus, the generation of flood susceptibility maps was based on dynamic and static criteria so that the evaluation between time scales was possible. While the reference period was used as a way of validating the model, in the future period, probable paths of societal narratives (SSP245 and SSP585) and their influences on flood risks at municipal (context I) and river basin levels (context II). Seeking to eliminate subjectivity about each criterion's importance and value functions, the flood risk approach used Shannon entropy weighting. The results made it possible to identify, as a physical context, a strong increase in impervious areas for the future and great influence of drainage density, as a social aspect, the influence of population density on the risk of flooding. The social aspect is important, as there is only a risk of flooding when people are exposed to the danger. In this way, the results obtained do not only identify areas more prone to risks but areas that, if subjected to events, will present greater damages and losses. In context I, the trajectories of municipalities in Paraíba, regarding the risks of flooding, between past and future, showed a tendency to increase the risks of flooding, especially in municipalities closer to the coast (east), and there is also a tendency to decrease risks. In municipalities located further west of the state, mainly due to the influence of bioclimatic variables. In context II, watershed-scale information traced different risk scenarios: on the SSP245 path, many watersheds will have critical levels of flood risk; on the other hand, on the SSP585 path, even with the reduction of flood risks in some basins, this path is marked by strong anthropic pressure and the predominant action of global warming. Even with the biases and uncertainties inherent to the methodologies applied and resulting from the limitation of data, the results generated in this research can contribute to the challenge of managing flood events by providing an approach capable of helping managers and planners in solving trade-offs and complex problems. New criteria and improved methodologies will be incorporated in future research to advance the flood risk model used in this work.