Aspectos Geológicos-Geotécnicos e análise cinemática da Cachoeira do Santuário: Implicações para o ecoturismo em Coromandel, Minas Gerais

Abstract

Coromandel, situated in the Mesorregion of Triângulo Mineiro and Alto Paranaíba, boasts a variety of natural attractions that draw visitors year-round. These sites include caves, rapids, rivers, and waterfalls, but they currently lack comprehensive geological and geotechnical evaluations. To address this gap, this undergraduate final project presents a geotechnical study of the Santuário Waterfall, aiming to support safe tourism. The rock massif constituting the waterfall is composed entirely of quartzite, exhibiting varying degrees of resistance and weathering. The quartzite shows incipient metamorphic foliation, with planes oriented at 240/30 (dip/dip direction). The waterfall's slope faces WSW (250°) and has an average inclination of 75°. Four families of discontinuities were identified: Family 1, oriented ENE-WSW, with planes dipping to the SSE (150°) at angles between 56° and 80°; Family 2, oriented NW-SE, with planes dipping to the SW (230°) at angles between 62° and 83°; Family 3, with discontinuities oriented NE-SW, and planes dipping to the NW (300°) at angles between 65° and 79°; and Family 4, predominantly oriented NW-SE, with planes dipping to the SW (28°) at angles between 58° and 72°. This family also contains smaller quantities of discontinuities oriented along the NE-SW direction, with planes dipping to the SE. According to the RDQ (Rock Quality Designation) and RMR (Rock Mass Rating) indices, the rock massif at the Santuário Waterfall is classified as “Reasonable”. The kinematic analysis of the discontinuities based on structural stereograms indicated the possibility of planar ruptures (22.2%) for Family 2, toppling ruptures (25%) for Family 1, and wedge failures (20%) for the intersections between the discontinuities of families 1 and 3 and families 2 and 3. The calculated safety factor, with a value of 2.8, indicates that the massif is stable concerning different types of ruptures. However, periods of intense rainfall in the Triângulo Mineiro and Alto Paranaíba between October and March can contribute to conditions of greater slope instability and, therefore, favor gravitational mass movements. In this sense, and based on the geological-geotechnical evaluation presented, it is recommended that two simple measures be implemented to reduce potential geological risk situations: 1) the installation of signage informing of the possibility of falling rocks at the base and sides of the waterfall and 2) that visits to the Santuário Waterfall should preferably be made during the dry season, between April and September.