https://repositorio.ufba.br/handle/ufba/524 2026-04-17T03:02:22Z 2026-04-17T03:02:22Z Jesus, Raija Cisneiros de https://repositorio.ufba.br/handle/ri/44394 2026-04-16T20:02:11Z 2025-09-29T00:00:00Z

Título: O efeito dos arenitos de praia no comportamento da linha de costa da praia de Arembepe, Camaçari, Litoral Norte do estado da Bahia Autor(es): Jesus, Raija Cisneiros de Primeiro Orientador: Guimarães, Junia Kacenelenbogen Abstract: Although beachrocks are considered coastal protection agents, the different ways in which they are distributed longitudinally and transversely on the beach does not allow this statement to be generalized. This work aims to evaluate the effect of beachrocks on the behavior of the coastline of Arembepe (North Coast of Bahia, Brazil), since in this locality there are two or more generations of beachrocks, located either in the nearshore, or on the beach face or in both positions, making this place a laboratory for studies of the influence of beachrocks in different locational situations. The methodology of the work consisted of 13 campaigns to survey beach profiles based on the Emery’s Method (1961), in addition to the mapping of beachrocks and coastlines from 1976 and 2022. 21 transects were also plotted to measure the displacement of the coastline between these years and calculated the respective rates and errors. The profiles were located in different situations: i) in circulation cells limited at the ends by beachrocks (profiles 1 to 3), corresponding to the southwestern section of the study area; ii) in front of a sandstone body attached to the beach face and another on the nearshore, without and with the presence of a channel between them (profiles 4 and 5, respectively), pattern that occurs in the central part of the study area; iii) on two faces of an salient with a discontinuous sandstone present in the nearshore (profiles 6 and 7), corresponding to the northeastern portion of the study area. The analysis of beach profiles 1 to 3 contributed to the understanding of sedimentary dynamics, showing seasonal changes in the direction of longshore drift and demonstrating a transport for NE between April and September, and for SO between October and March. This dynamic can be extrapolated to other coastal stretches in the North Coast of Bahia, which also have NE-SW coastline orientation and are subjected to the same atmospheric conditions. In addition, the results allowed to identify the influence of beachrocks in long (Holocene), medium (about 50 years) and short term. In the long run the coastline of Arembepe, seen in plan, is stepped, which resulted from the successive formation of asymmetrical tombolos, which were gradually calcified. In the medium term, in the southwestern part of the studied area, where the beachrocks have only the role of closing a circulation cell (profiles 1 and 3), a progradation was observed in the last 46 years, possibly associated with changes in wave regime. On the other hand, the central part of the study area, where beachrocks are present both on the beach face and in the nearshore (profiles 4 and 5), is in equilibrium, showing that in 1976 the tombolos were already consolidated. In the northeast section, in turn, there is a situation of progradation and stability. This pattern can be attributed to discontinuous nearshore beachrocks, which produces a coastline with intercalations of salients and coves, with different behaviors. In the short term, it was observed a great sedimentary dynamics and variability of the position of the coastline in the southwest section, where the beachrocks present at the ends of the circulation cell allow a beach rotation throughout the year. In the central part, the presence of beachrocks on the beach face was responsible for a little seasonal variation in the beach profiles and little variability in the position of the shoreline, reinforcing the idea that the sandstones on the beach face hinder the sediment exchange on the beach. In the northeastern section, the variability of coastline position was intermediate to the other two sections. Finally, it is concluded that the protection provided by beachrocks was not homogeneous on the beach of Arembepe, depending on the different situations in which they are: closing circulation cells, attached to the beach face or presenting themselves discontinuously on the nearshore. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Dissertação

2025-09-29T00:00:00Z Seabra, Gleide Mendes https://repositorio.ufba.br/handle/ri/44105 2026-02-26T11:09:01Z 2025-11-10T00:00:00Z

Título: Inventário e avaliação quali-quantitativa de sítios de geodiversidade na Bacia do Recôncavo no Nordeste do Brasil. Autor(es): Seabra, Gleide Mendes Primeiro Orientador: Barbosa, Natanael da Silva Abstract: The Recôncavo Basin, located in the eastern portion of the state of Bahia, Northeast Region of Brazil, is mostly covered by Mesozoic sediments, derived from taphrogenesis that began slightly before this era, still in the Paleozoic, during the fragmentation process of the supercontinent Gondwana. The chronology of the basin's formation is defined by three stages of rift evolution, with a complete and representative sedimentary sequence of all phases during the Permian (~298 and 252 Ma). The Permian record in northeastern Brazil begins with lithostratigraphic successions, with excellent seasonal coverage and diverse geological content. The scientific importance of the representative outcrops of the Recôncavo Basin is already being explored, through field trips, by some federal educational institutions. The area encompasses not only geological content but also landscapes with river formations, lakes, deltas, estuaries, valleys, floodplains, waterfalls, and all associated landscapes resulting from large-scale geological/fluvial processes. In addition to the significant and relevant geological history, scenic and touristic content of the Recôncavo basin, the production of significant quantities of hydrocarbons has been conditioned in this basin. The spatio-temporal variation of this lithostratigraphic succession presents scientific and educational potential, as well as economic importance, and has potential for the classification and evaluation of geological materials indicative of environmental protection. These factors justify the need for a geoconservation study, the objective of this work, which involves the inventory, quantification, and quantitative evaluation of geosites in the region. Using the methodology of the Geosites and Geodiversity Sites Registration and Quantification System - GEOSSIT (Mineral Resources Research Company - CPRM/Geological Survey of Brazil - SGB), six geosites were selected and analyzed based on their scientific, educational, and touristic values. The results indicate that the sites have high scientific value and potential for geoeducation, although they present a high risk of degradation due to their proximity to highways. This highlights that valuing this geoheritage is essential for geoconservation strategies and for regional sustainable development through geotourism. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Dissertação

2025-11-10T00:00:00Z Silva, Hailton Mello da https://repositorio.ufba.br/handle/ri/44047 2026-02-19T13:00:52Z 0012-12-01T00:00:00Z

Título: Aspectos naturais e antropogênicos associados ao rebaixamento do aquífero cárstico do platô de Irecê, Bahia. Autor(es): Silva, Hailton Mello da Primeiro Orientador: Leal, Luiz Rogério Bastos Abstract: The Hydrogeological Basin of the Verde and Jacaré Rivers, located in the north-central portion of the State of Bahia, is almost entirely overlain by an area of carbonate sedimentary rocks, which constitutes an important karst aquifer in the semi-arid region of Bahia. The clayey soil, with its reddish-yellow hue and high fertility, along with the relatively flat topography, favors agriculture, which is one of the main economic activities practiced in the region. However, given the intrinsic characteristics of a karst environment in a semi-arid climate, the lack of surface water, caused by the existence of rapid percolation zones and sinkholes that absorb rainfall and quickly incorporate it into underground drainage, as well as high evapotranspiration necessitates the search for groundwater as a means of irrigation for cultivated areas. Nevertheless, in recent decades, human occupation in the region has intensified and with the increase in cultivation, there has been a rise in drilling of tubular wells, requiring a disorderly extraction of groundwater, lowering the aquifer and jeopardizing the water potential of that reservoir. Similarly, deforestation for agricultural occupation has led to the extinction of springs responsible for feeding the rivers of this basin, transforming intermittent rivers into ephemeral ones. Likewise, the uncontrolled use of nutrients and pesticides in agriculture has contaminated the aquifer and rendered its waters unsuitable for human consumption. On the other hand, the lack of control over human occupation without adequate infrastructure for solid waste disposal and without appropriate sewage systems has contributed to this contamination due to the great fragility of the karst environment. Thus, this work aims to show that there is an association between anthropogenic and natural factors that are leading to the degradation of the Irecê karst aquifer. This objective was achieved by cross-referencing the karst characteristics of the aquifer, hydrogeological data from tubular wells, land use and occupation data obtained from satellite images and historical rainfall data in the region. It was then possible to conclude that the entire Irecê karst aquifer is subjected to anthropogenic pressure which together with the natural conditions imposed by a semi-arid climate and low rainfall could lead to stagnation of this aquifer. Similarly, this study determined that the central area of the Irecê Karst Aquifer is experiencing the greatest anthropogenic pressure, compromising both the quality and quantity of its groundwater and requiring greater attention from the management bodies in this region. As a result, suggestions were made for implementing actions that, if conducted correctly could assist in the management of the entire Irecê Karst Aquifer, with greater emphasis on the central area, thus helping to control the degradation of this important aquifer in Bahia. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Tese

0012-12-01T00:00:00Z Victorino, Ernesto Domingos https://repositorio.ufba.br/handle/ri/44046 2026-02-19T12:34:20Z 2025-12-16T00:00:00Z

Título: Caracterização mineral e implicações geometalúrgicas do depósito de níquel laterítico São João do Piauí. Autor(es): Victorino, Ernesto Domingos Primeiro Orientador: Gomes, Sylvio Dutra Abstract: The nickel laterite deposit at São João do Piauí (Piauí Nickel deposit) is located in northeastern Brazil, and presents a standard oxide laterite type profile. At deposit scale, the lateritic profile (with 80 m in the studied drillholes) is composed by a silicified ferruginous laterite as the most volumetrically representative unit. In lithogeochemical analyses the general context of the lateritic horizon Fe and Si show an inverse proportional relation. Subordinate layers (~3 m) of green saprolite, enriched in MgO, Ni and REE (~7 %, 0.6 %, ~200 ppm respectively) occur intercalated in the lateritic horizons. Rietveld refinement in X-ray diffraction data determined quartz, magnetite, hematite and goethite as the most common phases in samples from the oxide horizon. Rietveld quantitative results show that in samples from the ferruginous laterite unit, goethite is the Fe mineral most enriched in trace elements, including Ni, Cu, Co, REE. Refinement of stoichiometry in magnetite-maghemite solid solution from de ferruginous laterite shows that most of the magnetite identified in the qualitative XRD analyses is in fact the isomorphic maghemite. In this context, the Rietveld analyses proved to be a powerful tool in the mineral characterization of magnetite enriched. Editora / Evento / Instituição: Universidade Federal da Bahia Tipo: Dissertação

2025-12-16T00:00:00Z