Análise da ocorrência de eventos de deslizamentos no município de Jaboatão dos Guararapes e sua relação com eventos hidrometeorológicos.

Abstract

Given the increasing occurrence of landslides on the East Coast of Northeast Brazil (CLNEB), and considering the vulnerability of the Pernambuco municipality of Jaboatão dos Guararapes, it becomes relevant to understand the relationship between rainfall and mass movements to contribute to disaster risk reduction measures related to landslides in this municipality. In this sense, the main objective of this research was to relate the precipitation with the occurrence of landslides in the municipality of Jaboatão dos Guararapes, resulting from daily and accumulated precipitation in previous days in the period from 2016 to 2020, as well as identify the areas most affected by landslides in the municipality. It was sought analyze the occurrences of landslides and precipitation in terms of temporal variability and space, as well as analyzing an extreme rainfall event through parameters meteorological events that triggered the occurrence of landslides in several CLNEB cities in May 2017. The ability of a regional numerical model in represent the rain of that event. To carry out this study, information was used that allowed identifying the areas with the highest occurrence of landslides in the municipality of Jaboatão dos Guararapes, to evaluate the spatio-temporal variability of rainfall occurrence and landslides, analyze the amount of precipitation necessary for the occurrence of landslides, check the atmospheric conditions of a relevant event at CLNEB and examine the ability of the Regional Climate Model (RegCM) to represent the spatio-temporal variability of the rain in the case study. the dataset included annual maps of land use and occupation; vector data of susceptibility and sectors of risk to landslides; reports of landslide occurrences; weather reports; in addition to rainfall records from the National Center for Disaster Monitoring and Alerts Natural (CEMADEN). The results showed that over the years, the municipality of Jaboatão dos Guararapes, underwent an intense transformation in its urban space, with the population increase inhabiting areas unsuitable for housing, and consequently, creating several risk areas in the city. This accelerated urbanization process, combined with accumulated of rain ended up contributing in a very decisive way to the occurrence of landslides. The relationship between landslides and rainfall through precipitation thresholds using the relationship of the accumulated precipitation of the event and its duration (ED) and the intensity with duration (ID) showed that landslides are influenced by both short-term and long-term rainfall. of long duration, with the highest predominance of cases observed in short periods. The ED precipitation threshold presented better performance in relation to the ID threshold, as verified by the value of the coefficient of determination (R2). The extreme event case study of rain in CLNEB that happened in May 2017, caused landslides in Jaboatão dos Guararapes as well as in other municipalities of Alagoas, Pernambuco and Paraíba, demonstrating the fragility of the terrain to this type of natural threat at CLNEB. The investigation on meteorological aspects showed that this event was associated with the convergence of low-level moisture over the Atlantic Ocean. At high atmospheric levels, it was observed that the largest nuclei of divergence of the wind resulted from the convection of the surface. In view of these results, there was a need for continuous monitoring of atmospheric conditions at CLNEB, due to the importance of obtaining forecasts of quality on precipitation in the region. Likewise, exploring the relationship between the processes of precipitation and landslides in this region may provide objective criteria for evaluating risk.