Susceptibility mapping to mass movements in the Jiquiriçá Valley - BA

Abstract

This study analyzes the susceptibility to mass movements in the Jiquiriçá Valley (Bahia, Brazil), a region particularly exposed to natural disasters during periods of intense rainfall. These phenomena, which involve the displacement of soil and rock on slopes, are influenced by factors such as climate, topography, and land use, resulting in significant environmental and social impacts. The objective of this work is to map the susceptibility to mass movements in the aforementioned municipality under scenarios of heavy rainfall and land use and land cover changes. To achieve this, the Analytic Hierarchy Process (AHP) method was employed in combination with geoprocessing, considering factors such as slope, soil classes, soil texture, dissection index, hypsometry, slope orientation, lithology, geological fracture density, rainfall (1970–2000 and 2021), and land use and land cover (1985 and 2021). The results reveal a 15.36 % increase in areas classified as having “Very High” susceptibility, particularly in regions with steep terrain and sedimentary lithologies, which are prone to mass movements. In contrast, there was a 33.56% decrease in areas classified as having “Low” susceptibility, indicating a growing risk over time. Therefore, the mapping carried out is of utmost importance to support natural disaster prevention measures and to inform territorial planning.