ORCID Profile
0000-0002-9448-1313
Current Organisation
Universidade de Brasília
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Publisher: Elsevier BV
Date: 04-2021
Publisher: Revista Brasileira de Geografia Fisica
Date: 06-04-2020
DOI: 10.26848/RBGF.V13.1.P302-321
Abstract: O carste se desenvolve sobretudo pela ação da dissolução em subsuperfície, na interação da água com rochas solúveis, especialmente as carbonáticas. Apesar do processo de carstificação nem sempre se apresentar em superfície, a ocorrência de dolinas, feições consideradas características, indica maior proeminência desse fenômeno. Muitos trabalhos internacionais se dedicaram ao mapeamento de dolinas com objetivos ersos, como comparar o nível de carstificação e evolução dos ambientes onde estão inseridas, relacionar o desenvolvimento destas feições com estruturas geológicas ou realizar análises hidrológicas de caráter ambiental. Por outro lado, são poucos os trabalhos com esta temática realizados no Brasil, parte concentrada em regiões cársticas tradicionais, como o Vale do Ribeira-SP, Chapada Diamantina-BA e nos carbonatos de Minas Gerais, e os demais dispersos pelo país, muitos em rochas não carbonáticas. Neste sentido o objetivo deste artigo é realizar uma revisão dos trabalhos sobre mapeamento de dolinas, com enfoque nos aspectos morfométricos e quantificação, visando especialmente elaborar um primeiro panorama sobre como o tema é abordado no Brasil. Observou-se que a maior parte dos estudos nacionais alcançou resultados de frequência (nº/km²) bastante inferiores aos identificados em estudos internacionais. Essa discrepância foi atribuída a alguns aspectos, como a adoção de fontes de dados inadequadas em escala abrangente, a escolha de áreas muito extensas para a análise ou de fato a investigação em áreas pouco propícias a ocorrência de dolinas. An Overview of Doline Mappings in Brazil, Karst's Elemental Features A B S T R A C TKarst develops mainly by the action of dissolution in subsurface, in the interaction of water with soluble rocks, especially carbonates. Although the karsification process does not always appear on the surface, the occurrence of dolines, features considered characteristic, indicates a greater prominence of this phenomenon. Many international works have been devoted to the mapping of dolines with different objectives, such as comparing the level of karsification and evolution of the environments in which they are inserted, to relate the development of these features to geological structures or to perform environmental hydrological analyzes. On the other hand, there are few studies on this subject in Brazil, concentrated part in traditional karst regions such as Vale do Ribeira-SP, Chapada Diamantina-BA and carbonates of Minas Gerais, and the others scattered around the country, many in non-carbonate rocks. In this respect, the objective of this article is to review the work on doline mapping, with a focus on morphometric aspects and quantification, aiming in particular to elaborate a first overview about how the theme is approached in Brazil. It was observed that most of the national studies reached frequency results (n°/km²) much lower than those identified in international studies. This discrepancy was attributed to some aspects, such as the adoption of inadequate data sources in a wide scale, the choice of very extensive areas for analysis or indeed the investigation in areas less favorable to the occurrence of dolines.Keywords: karst doline density.
Publisher: GN1 Genesis Network
Date: 2017
Publisher: FapUNIFESP (SciELO)
Date: 09-2020
Publisher: Wiley
Date: 29-06-2020
Publisher: MDPI AG
Date: 30-08-2018
DOI: 10.3390/RS10091373
Abstract: Launched in 2014, the Global Precipitation Measurement (GPM) mission aimed at ensuring the continuity with the Tropical Rainfall Measuring Mission (TRMM) launched in 1997 that has provided unprecedented accuracy in Satellite Precipitation Estimates (SPEs) on the near-global scale. Since then, various SPE versions have been successively made available from the GPM mission. The present study assesses the potential benefits of the successive GPM based SPEs product versions that include the Integrated Multi–Satellite Retrievals for GPM (IMERG) version 3 to 5 (–v03, –v04, –v05) and the Global Satellite Mapping of Precipitation (GSMaP) version 6 to 7 (–v06, –v07). Additionally, the most effective TRMM based SPEs products are also considered to provide a first insight into the GPM effectiveness in ensuring TRMM continuity. The analysis is conducted over different geomorphic and meteorological regions of Pakistan while using 88 precipitations gauges as the reference. Results show a clear enhancement in precipitation estimates that were derived from the very last IMERG–v05 in comparison to its two previous versions IMERG–v03 and –v04. Interestingly, based on the considered statistical metrics, IMERG–v03 provides more consistent precipitation estimate than IMERG–v04, which should be considered as a transition IMERG version. As expected, GSMaP–v07 precipitation estimates are more accurate than the previous GSMaP–v06. However, the enhancement from the old to the new version is very low. More generally, the transition from TRMM to GPM is successful with an overall better performance of GPM based SPEs than TRMM ones. Finally, all of the considered SPEs have presented a strong spatial variability in terms of accuracy with none of them outperforming the others, for all of the gauges locations over the considered regions.
Publisher: EDUFU - Editora da Universidade Federal de Uberlandia
Date: 30-07-2019
Abstract: Neste trabalho de revisão buscou-se inicialmente colecionar as tipologias de classificação do carste utilizadas através do tempo no mundo e algumas de suas aplicações no Brasil. É dado enfoque a questões morfogenéticas responsáveis pelo desenvolvimento de feições cársticas superficiais, fruto de processos nem sempre visíveis que operam em subsuperfície. Os mecanismos de desenvolvimento das dolinas, consideradas feições elementares e diagnósticas do carste, são discutidos principalmente entre processos de dissolução, subsidência e colapsos. É apresentada uma proposta terminológica de classificação genética de dolinas baseada nas principais publicações internacionais sobre o tema. Por fim é discutida também a questão morfológica das depressões cársticas, critério igualmente utilizado para a separação tipológica destas feições.
Publisher: Revista Brasileira de Geomorfologia
Date: 29-11-2009
Abstract: Este trabalho objetiva classificar formas de depressões fechadas encontradas no médio-baixo vale do Ribeirão Santana e identificar a idade de depósitos orgânicos nas encostas e nos terraços fluviais. Busca-se entender a relação entre o aprofundamento de dolinas e a abertura de concavidades suspensas ou topograficamente ajustadas aos canais principais. Os resultados indicam quatro grupos de depressões, que podem demonstrar estágios evolutivos distintos, assim como o mapeamento de concavidades e depósitos de encostas. Datações absolutas apontam idades similares entre sedimentos no interior de depressões e nas concavidades estruturais suspensas, podendo demarcar evento de ajuste de nível de base com propagação regional.
Publisher: Revista Brasileira de Geografia Fisica
Date: 07-04-2020
DOI: 10.26848/RBGF.V13.2.P487-509
Abstract: Este artigo se trata de uma revisão metodológica de técnicas indiretas de mapeamento pedológico, envolvendo ensaios granulométricos, SIG e sensoriamento remoto dentro do mapeamento digital de solos, espectrorradiometria e Georadar (GPR), comparados e/ou associados às técnicas diretas como coleta, descrição de trincheiras ou perfis, análise da paisagem. O mapeamento digital de solos (MDS) vem se provando com uma ferramenta eficiente desde o início do ano 2000, associadas a outros métodos como o sensoriamento remoto e análises laboratoriais, o MDS forneceu ao mundo mapas que representam bem a realidade dos solos. Mas as técnicas diretas ainda são usuais e eficientes, e podem ser associadas aos métodos indiretos, para que o mapeamento de uma pequena área possa ser espalhado regionalmente. A busca por técnicas de baixo custo, eficiência e praticidade tem levado pesquisadores a buscarem técnicas como o Georradar para verificar a profundidade do solo, sem que seja necessário a destruição de perfis por meio da abertura de trincheiras, como também ao uso de imagens de radar capaz de oferecer um produto de alta resolução espacial, independentemente da altitude da plataforma, e que tem auxiliado na extração de ersas informações da paisagem diretamente ligadas à pedogênese. Esta pesquisa tem o intuito de buscar a evolução do mapeamento pedológico através das ersas técnicas citadas, e bem como a associação entre os ersos métodos para gerar um mapa de solos de alta precisão. Efficiency analysis of indirect methods for soil mapping against direct techniques, and their possible associations: A methodological reviewA B S T R A C TThis article is a methodological review of indirect techniques of pedological mapping, GIS and remote sensing within digital soil mapping, spectroradiometry and Georadar (GPR), compared to landscape analysis. Research has shown that digital soil mapping (MDS) has been an efficient tool since the beginning of the year 2000, combined with other methods such as remote sensing and laboratory analysis, MDS has provided the world with maps that represent the reality of soils well. But direct techniques are still common and efficient, and can be associated with indirect methods, so that local mapping information can be dispersed regionally. The search for low-cost, efficient and practical techniques has led researchers to look for techniques such as Georadar to check the depth of the soil, without the need to destroy profiles by opening trenches, as well as using radar images. which provide a high spatial resolution product, regardless of the platform's altitude, and which has helped in the extraction of various landscape information directly linked to pedogenesis. Spectroradiometry is a methodology that works with the measurement of radiant electromagnetic energy, and allows for quick associations between targets and spectral curves, allowing the creation of global libraries of these curves. Radiometry in turn has been widely used in systems that operate in the microwave frequency range, ranging from 1mm to 1m in length, and allow you to locate objects. This research aims to seek the evolution of pedological mapping through the various techniques mentioned, as well as the association between the various methods to generate a highly accurate soil map.Keywords: Soil Mapping GPR Spectroradiometry Orbital Sensors
Publisher: Society of Exploration Geophysicists and Environment and Engineering Geophysical Society
Date: 23-03-2017
Publisher: Journal Agriculture and Forestry
Date: 30-06-2021
Publisher: Revista Brasileira de Geomorfologia
Date: 30-05-2017
Abstract: O presente estudo tratou das feições doliniformes na bacia do alto rio Preto. De um total de 177 feições identificadas, a maioria está próxima ou conectada à drenagem, sendo menos circulares que outras identificadas como isoladas. Tais feições possuem agrupamentos nítidos e sua distribuição indica que são controladas por falhas associadas a dobras da Faixa de Dobramentos Brasília, diante da comparação de seus eixos de orientação com alinhamentos geológicos. Foi observado que 90% das depressões se assentam sobre as rochas carbonáticas do Grupo Bambuí.
Publisher: Wiley
Date: 11-04-2023
DOI: 10.1002/ESP.5580
Abstract: Karst areas are vulnerable landscapes which, if unprotected, could be permanently degraded. To bridge the gap existing in the reduction of on‐ and off‐site impact of restored tropical karst areas, this study was carried out in a 3.5 ha karst watershed of the Brazilian savanna (Cerrado). Precipitation, surface runoff, and soil loss were measured in representative runoff plots (22.1 × 1.84 m), used to assess the watershed erosion and sediment yield to a downstream sinkhole. The study was carried out during three hydrologic years, between September 2018 and May 2020. The predominant soils in the watershed were Lithic entisol and Quartzsamment, and the original land covers were natural savanna, seasonal forest, and degraded pastureland ( Andropogon gayanus ). The latter was restored with native savanna species, in the lower part of the watershed, and with a reformed pastureland, in the upper part. The USLE rainfall erosivity ( R ), soil erodibility ( K ), and soil cover ( C ) factors, runoff, soil loss, and the original soil and sediment textures were obtained from the runoff plots. The watershed soil loss and sediment yield were obtained by the USLE and GIS. Precipitation and rainfall erosivity ranged from 936 to 1223 mm, and from 6694 to 7746 MJ mm ha −1 h −1 , in the period, respectively. Although the ecological watershed restoration reduced mean soil loss from 11.6 to 5.8 Mg ha −1 year −1 , and sediment yield from 29.2 to 14.6 Mg year −1 , on‐ and off‐site soil loss tolerances were still exceeded in 29 and 61% of the basin area, respectively. Ecological restoration also reduced the sand and clay content of the sediment entering the underground caves and river downstream, contributing to their hydrologic sustainability.
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-10450
Abstract: & & The hillslope-stream connectivity, an important contributor to streamflow generation and surface water quality, depends both on the surface networks and the subsurface structure. The connectivity is dynamic and affected by certain processes (meteorological events) and local site conditions and it may have coupled or decoupled accordingly. Compared to factors affecting the surface networks such as vegetation or slope, subsurface connectivity is challenging to assess because of the limited availability of direct observations. In this context, the present study explored the potential of time-lapse ground-penetrating radar to quantify this connectivity together with in situ soil moisture measurements at a small hillslope in Capetinga stream, Brasilia, Brazil. The study period covers the dry and wetting periods from August 2015 to February 2016.& & & & Geophysical surveys were conducted using 200 MHz and 400 MHz antennas with the approximate depths of investigation 4m and 9m respectively, covering an area of approximately 200 m& sup& & /sup& in the considered watershed. Data were acquired along five parallel profiles and one orthogonal profile to the Capetinga stream. At different locations on these profiles, the soil moisture was estimated at different depths using gravimetric and time-domain reflectometry probes to compare both direct and indirect data. This configuration allowed the characterization of the subsurface as well as the change in degree of moisture in different seasons.& & & & A multi-attribute analysis, including coherence, energy and litude of the signals was applied to the dataset at considered time scales to highlight the discontinuities of the subsurface in terms of structures and water content. Additionally, a Hilbert transform analysis provided an extra layer to achieve the study objectives.& & & & The present study demonstrates that time-lapse GPR surveys together with in situ data offer a practical and nondestructive way of understanding complex subsurface flow processes across the landscape that lead to hillslope-stream connectivity in the field. This study is an initial step to understand the cerrado environment that is a unit of essential landscape at the watershed scale.& & & & & strong& Keywords: & /strong& Attribute analysis & non-invasive Hilbert transportation time-domain reflectometry& & & & & & &
Publisher: Springer Science and Business Media LLC
Date: 2021
Publisher: UNESP - Universidade Estadual Paulista
Date: 25-06-2018
DOI: 10.5016/GEOCIENCIAS.V37I2.12539
Abstract: Ever increasing urbanization over the thick and less cohesive soil of the Federal District (DF), Brazil has increased area's vulnerability to natural hazards, especially the soil erosion and mass movement. This preliminarily study applied noise based geophysical techniques like power spectral density (PSD), horizontal to vertical spectral ratio (HVSR), multichannel analysis of surface waves (MASW) and noise interferometry to a mass movement in Brasilia for the understating of geodynamic processes working in the background of these hazards. Here obtained results show a uniform stratigraphic peak at 2 Hz observed on all HVSR curves, a four layered shear wave section was obtained by MASW. Dispersion curve (frequency vs phase velocity) shows first and second fundamental modes at frequencies of 5 and 25 Hz, respectively. Noise correlograms show time delay larger than +- 0.5 sec on the waveforms of ZR (vertical-radial) component, mainly in acausal part. Relative velocity changes calculated by stretching technique show anomalous trends in response to rainfall events. Follow research will focus on the detection of possible changes in noise records within mass movement mainly related to natural triggering factors (rainfall and river erosion) under more controlled data conditions.
Publisher: Revista Brasileira de Geomorfologia
Date: 07-2022
Abstract: A carga sedimentar fluvial pode indicar alterações na dinâmica ambiental em bacias hidrográficas, como processos intensificados de erosão, assoreamentos e diminuição de oxigênio disponível em rios e lagos, entre outros fatores. O objetivo desse estudo foi monitorar a vazão e a carga sólida em suspensão durante eventos pluviais de diferentes magnitudes próximo à foz do Ribeirão do Gama, em Brasília, Distrito Federal, e avaliar qual o nível de contribuição da produção de sedimentos ao lago Paranoá, entre dezembro de 2015 e março de 2016. Para isso, a vazão foi estimada por meio de medições discretas a vau com auxílio de molinete e método acústico. O nível foi obtido com linígrafo digital, permitindo estabelecer uma curva-chave a partir da equação exponencial. Amostradores manuais integradores e amostrador automático pontual foram utilizados para obter dados de descarga sólida. O tempo de concentração pluvial foi calculado para onze eventos monitorados, e testadas as correlações entre chuva, vazão, carga sólida e turbidez. Os resultados indicaram histereses com dois comportamentos: laço em oito e laço no sentido anti-horário. É possível inferir que a à produção de sedimentos na bacia do Ribeirão do Gama possui uma resposta direta relacionada ao escoamento superficial e infiltração de água no solo.
Publisher: Wiley
Date: 28-06-2020
Publisher: Revista Brasileira de Geomorfologia
Date: 07-2020
Abstract: As dolinas são feições indicadoras do sistema cárstico e além de atestarem processos evolutivos, também apresentam importância no contexto das dinâmicas hídricas e ambientais. O mapeamento dessas feições serve como base para ersas análises da paisagem e exige grande dispêndio de tempo e recursos, com significativa subjetividade inerente à técnica de aquisição ou à problemas de escala. A melhoria da resolução espacial nas bases de dados permitiu maior precisão nos mapeamentos de dolinas com o uso de modelos digitais de elevação e técnicas de geoprocessamento, automatizadas ou manuais. Entretanto, as dificuldades de detecção dos pontos de absorção que in idualizam as dolinas, e os limites estabelecidos para seu perímetro dificultam a comparação entre estudos, agregando incertezas nos atributos espaciais como área, profundidade e eixo principal. Neste artigo são discutidas as principais metodologias de mapeamento de dolinas e sintetizadas as estratégias mais utilizadas para superar erros de omissão de feições verdadeiras, problemas com a detecção de falsos positivos e a delimitação mais precisa das depressões cársticas.
Publisher: MDPI AG
Date: 26-11-2019
DOI: 10.3390/SU11236672
Abstract: Geophysical methods have a varying degree of potential for detailed characterization of landslides and their dynamics. In this study, the application of four well-established seismic-based geophysical techniques, namely Ambient Noise Interferometry (ANI), Horizontal to Vertical Spectral Ratio (HVSR), Multi-Channel Analysis of Surface Waves (MASW) and Nanoseismic Monitoring (NM), were considered to examine their suitability for landslide characterization and monitoring the effect of seasonal variation on slope mass. Furthermore, other methods such as Ground Penetrating Radar (GPR) and DC Resistivity through Electrical Resistivity Tomography (ERT) were also used for comparison purpose. The advantages and limitations of these multiple techniques were exemplified by a case study conducted on Sobradinho landslide in Brazil. The study revealed that the geophysical characterization of the landslide using traditional techniques (i.e., GPR, ERT and MASW) were successful in (i) the differentiation between landslide debris and other Quaternary deposits, and (ii) the delineation of the landslide sliding surface. However, the innovative seismic based techniques, particularly ambient noise based (HVSR and ANI) and emitted seismic based (NM), were not very effective for the dynamic monitoring of landslide, which might be attributed to the short-time duration of the data acquisition c aigns. The HVSR was also unsuccessful in landslide site characterization i.e., identification of geometry and sliding surface. In particular, there was no clear evidence of the light seasonal variations, which could have been potentially detected from the physical parameters during the (short-time) ambient noise and microseismic acquisition c aigns. Nevertheless, the experienced integration of these geophysical techniques may provide a promising tool for future applications.
Publisher: Revista Brasileira de Geografia Fisica
Date: 06-07-2023
Publisher: Wiley
Date: 26-06-2020
Publisher: Schweizerbart
Date: 03-2011
Publisher: MDPI AG
Date: 16-11-2022
DOI: 10.20944/PREPRINTS202209.0447.V2
Abstract: Identifying ambient noise-based (ANb) signatures of streams can help in the estimation of their erosive potential (EP) that promotes reverie landslides and soil losses in the fluvial valleys. This is particularly imperative on flooding or rainy days, leading to stronger erosion-prone conditions (colluvium and boulders) of the valley beds inferred from georadar attribute analysis. Developing such research direction can benefit the local communities, as is the case with the Cerrado region of Brazil, where these phenomena have high destructive potential with social, economic, and climatic implications. For the present study, a seasonal stream in the Federal District of Brazil was investigated by ANb monitoring supported by Ground Penetration Radar (GPR) for site characterization. The ANb monitoring was conducted (at a safe distance) with a seismometer over several durations of dry and rainy conditions. The power spectral density (PSDs) was computed as a function of several variables, including weather conditions (rainfall, wind speed, and pressure), time-frequency spectrograms, and ambient noise displacement root mean square (RMS). This analysis also considered the single station horizontal-to-vertical spectral ratio (HVSR), where rain, wind, pressure, river flow and anthropogenic signatures were evident (at selective frequency ranges). Multi-peaks that emerged on the HVSR curve were further analyzed to identify litude and frequency changes, and the three peaks shift on average to a lower position during the rainy period. The GPR litude and waveform variation features were attributed to the stratigraphy (i.e., the boundary between valid and invalid regions and coherence value) of the floodplain and regions susceptible to erosion (erosion-prone lithological spots). This approach provides the basis for non-destructive monitoring tools enabling the detection of 'seismic signatures' and weak spots of the fluvial channels for improving environmental management.
Publisher: Wiley
Date: 23-06-2020
Publisher: Instituto de Geociencias - UFRJ
Date: 20-08-2018
Publisher: Instituto de Geociencias - UFRJ
Date: 30-11-2017
Publisher: MDPI AG
Date: 28-09-2022
DOI: 10.20944/PREPRINTS202209.0447.V1
Abstract: The seasonal soil losses and frequent shallow landslides in the Cerrado region of Brazil have high destructive potential with social, economic, and climatic implications. As fluvial systems substantially drive such environmental threats therefore, it is essential to conduct geological site characterization and continuously monitor the seasonal erosive potentials of the rivers and streams. However, in such unstable and sensitive conditions, traditional intrusive investigation approaches may not be safe therefore, the geophysical investigation might offer a good alternative. For the present study, a geophysical approach (particularly the seismic method) was adopted to examine the seismic footprints and GPR site characterization of a seasonal stream in the Rua do Matto, Brasilia, Brazil. The monitoring was conducted (at a safe distance) on the intermittent stream over several durations of dry (no rain) and rainy (flood) conditions. After pre-processing the raw data, the power spectral density (PSDs) was computed as a function of several variables (wind speed), time-frequency spectrograms, ambient noise displacement root mean square (RMS), the single station horizontal-to-vertical spectral ratio (HVSR) curves. In addition, change-point analysis was used for comparing the ambient noise with wind speed (both were well correlated). The GPR litude and waveform variation features were attributed to the subsurface material and the presence of boulders in the floodplain as well as regions (low coherence value) susceptible to erosion (weak spots). The river flows were evident on the mean probabilistic PSD values, spectrograms, HVSR curves and different patterns of RMS displacements (at selective ranges of frequency). The multi-peaks emerged on the HVSR curve are further analyzed for changes in litude, width and troughs possibly related to river activities and soil moisture due to rain. The approach provides the basis for non-destructive monitoring tools enabling the detection of 'seismic signatures' and weak spots of the fluvial channels for improving their environmental management.
Publisher: EDUFU - Editora da Universidade Federal de Uberlandia
Date: 06-2022
Abstract: O carste apresenta regiões de conexões entre os sistemas fluviais e cársticos o fluviocarste, dispondo de feições típicas, como os vales secos. Tais feições vêm sendo estudadas de ersas formas para contribuir no entendimento da dinâmica geomorfológica do carste. Este estudo visa fazer uma revisão sobre vales secos em sistemas cársticos, tendo em vista observar o potencial científico destas áreas para ersas aplicabilidades. A revisão utilizou como principal forma de busca a plataforma Web Of Science (todas as bases), abrangendo o período entre 1945-2020, que abordavam sobre tais feições, com o uso das seguintes palavras-chave: karstic valley, dry valleys, blind valley, relict valley, ancient valley, fossil valley, solution valley, paleovalley e paleokarst valley, resultando em vinte e sete trabalhos, com ersas propostas de análise, evidenciando os fatores envolvidos na dinâmica fluviocárstica. O levantamento permite observar que são poucos estudos considerando a extensão de ocorrência de rochas carbonáticas no mundo, havendo concentração das pesquisas no continente europeu. No Brasil, apesar de dispor de regiões carbonáticas e das várias áreas mapeadas com ocorrência de cavernas, principalmente no bioma Cerrado, não há pesquisas sobre o tema, mesmo que viabilizem a identificação dos fatores que influenciam evoluções dos sistemas fluviocársticos.
Publisher: FapUNIFESP (SciELO)
Date: 2019
Publisher: Copernicus GmbH
Date: 20-06-2022
DOI: 10.5194/ICG2022-423
Abstract: & & The studied region located in the Rio Vermelho watershed, situated at the foot of the & em& Serra Geral de Goi& #225 s& /em& in the Brazilian Cerrado, hosts a covered fluviokarst system containing ~150 mapped caves that capture the rivers (sediment loads) upstream. The present study aims at developing a better understanding of the geomorphological controls, considering the impacts of climatic conditions and land use types on the production and transport of the sediments to the caves using an integrated approach (GIS mapping, hydrosedimentological monitoring, and geochronological analysis).& & & & The preliminary results indicate the influence of two sites on sediment production: a) downstream, constituted by the karstic system developed in the Neoproterozoic carbonates (Bambu& #237 group), where the soils are occupied by natural vegetation or pastures (family farming), and, b) upstream, on a plateau, which supplies water to the karstic system, with soils developed on Cretaceous sandstones (Urucuia group), the areas of growing mechanized agriculture. Models of the upper and lower fluviokarst systems are developed using the soil types and recharge zonation information. The chronology of the preserved sedimentary deposits, formed by the alternation of clayey and sandy facies, has been established, between 60ky and 200ky in the upper cavities and up to 20 ky in the fluviokarst blind valleys. Hydrosedimentological monitoring revealed the production of ~ 9 Mg ha-1yr-1 of sediments from degraded soils, while 2.0 Mg ha-1yr-1 are produced from soils having received the conservation protocol, a lower value than the geological rate as established in the literature. The sediments transported in the karst are poorly sorted compared to those in the rivers and an increase in the particulate load during floods (& against ~500 mg/L).& & & & There is still a lack of evidence about the origin of the water and sediments circulating in this karst system. Further studies on fresh sedimentary deposits in the recent sinkholes may help to better quantify recent paleo-environmental modifications and the effects of anthropogenic activities upstream.& & & & & strong& Keywords: & /strong& GIS Geochronology Blind valleys C14 & Fluviokarst& &
Publisher: Brazilian Geophysical Society
Date: 03-08-2017
DOI: 10.1190/SBGF2017-340
Publisher: Copernicus GmbH
Date: 20-06-2022
DOI: 10.5194/ICG2022-424
Abstract: & & For seldom investigated Brazilian caves, detailed non-invasive mapping is crucial for environmental, ecological, and geological investigations. However, the Cerrado region of Brazil hosts covered karst (underlain by a thick clayey layer) which makes its non-invasive mapping difficult using the readily available tools. In this study, we applied a geophysical technique to establish the linkage (continuity) among the three caves named & em& Trimba, Pasto de Vaca I& /em& , and & em& Pasto de Vaca II & /em& in the environmentally protected area of River& em& Vermelho, & /em& Goias, Brazil.& & & & Our analysis started with the optimization of the electrode array geometry and its depth of penetration in the area. A forward model was chosen based on the site where the river enters the cave and soil-clay-carbonate lithological contacts are exposed on the surface. As there are well-developed drainage networks and cave development is attributed to fluvial influences that still have subsurface water flows in most of the places. Therefore, buried streams were also considered in the numeral approximation study. Findings from the numerical simulation indicated that the best results could be obtained using either the dipole-dipole, pole-dipole, or Wenner-Schlumberger array configurations, with an inter-electrode spacing of 2.5 meters.& & & & Hence, a dipole-dipole array of electrodes was selected to acquire the DC electrical resistivity data. Considering the objective of the study, the measurements were carried out using 72 electrodes were spaced 2.5 m apart and arranged in seven electrical resistivity tomography (ERT) profiles perpendicular to the one end of & em& Trimba cave& /em& , covering the entire length of & em& Pasto de Vaca I& /em& and the beginning of & em& Pasto de Vaca II& /em& cave marked on existent caves topography.& & & & In the first stage of resistivity data processing, a manual inspection and consequent removal of bad data points to improve the inversion results were conducted seeking a possible reduction in root mean square error. The inversion models, represented through 2D sections, indicated anomalous resistivity areas, interpreted as regions of subsurface cavity. Additionally, a geomodeling approach was used for improving the presentation of the inversion results (resistivity variables) in 3D. The latter revealed anomalous zones present on all profiles, attributed to the presence of a subsurface cavity.& & & & The geophysical results made it possible to detect the continuity of the same cave from north to south, contrary to the previously held assumption about the existence of three in idual caves. Results encourage the integrated application of geophysical techniques for further detailed investigations.& strong& & /strong& & & & & & strong& Keywords: & /strong& Cerrado Electrical Resistivity Array optimization, Geomodeling& &
Publisher: Revista Brasileira de Geografia Fisica
Date: 29-08-2022
DOI: 10.26848/RBGF.V15.5.P2327-2339
Abstract: O mapeamento da superfície potenciométrica em aquíferos cársticos e físsuro-cársticos, em muitos casos, pode ser complexo em função da anisotropia e heterogeneidade destes sistemas, que comumente ocorrem de forma compartimentada. O presente trabalho apresenta um método para a confecção de mapas de isopiezas em aquíferos hospedados em rochas carbonáticas, incluindo os seguintes passos: i) caracterização do modelo conceitual do aquífero e enquadramento das condições de contorno ii) extração dos lineamentos estruturais regionais e locais iii) avaliação dos dados potenciométricos pontuais e verificação de contrastes em poços situados em diferentes compartimentos iv) interpolação dos dados de poços separadamente em cada compartimento e v) união dos diferentes blocos para recomposição da área original. O método foi testado em uma área de aquífero cárstico situada no alto curso da bacia do Rio Corrente na região nordeste do estado de Goiás. O produto final mostra diferentes comportamentos do fluxo hídrico subterrâneo quando se considera o mapa confeccionado como um sistema único e o mapa potenciométrico resultante da união dos diferentes blocos. Como resultado final da proposta, é possível afirmar que a confecção dos mapas a partir da separação dos blocos pode resultar em um produto mais coerente com a realidade e com maiores possibilidades de aplicação para os diferentes fins (estudo de isores de bacias hidrogeológicas, comportamento de plumas de contaminação, direções regionais de fluxo etc.).Palavras-chave: fluxo subterrâneo, carga hidráulica, interpolação. Methodology for Drawing Potentiometric Maps in Karstic and Fissure-Karstic Aquifers: Case Study in the Upper Current River Basin, Mambaí, GO ABSTRACTThe mapping of the potentiometric surface in karstic and fissure-karstic aquifers, in many cases, can be complex due to the anisotropy and heterogeneity of these systems, which commonly occur compartmentally. The present work presents a method for the preparation of potenciometric maps in aquifers hosted in carbonate rocks, including the following steps: i) characterization of the conceptual model of the aquifer and framing of the boundary conditions (ii) extraction of regional and local structural lineaments iii) evaluation of single point potentiometric data and verification of contrasts in wells located in different compartments iv) interpolation of the well data separately in each compartment and v) union of the different blocks for composition of the original area. The method was tested in an area of karstic aquifer located in the high course of the Corrente River watershed in the northeastern region of Goiás State, Central Brazil. The final product shows different behaviors of the groundwater flow when considering the map made as a single system and the potentiometric map resulting from the union of the different blocks. As a final result of the proposal, it is possible to affirm that the mapping from the separation of blocks can result in a product more coherent with reality and with greater possibilities of application for the different purposes (study of hydrogeological basin iders, behavior of contamination plumes, regional flow directions, etc.).Keywords: groundwater flow, hydraulic head, interpolation.
Publisher: Revista Brasileira de Geomorfologia
Date: 31-03-2019
Abstract: O presente estudo tem por objetivo fazer uso de tecnologia GPR (Ground Penetration Radar), também conhecido como Georadar, para distinguir os materiais aluvionares, coluvionares e eluvionares depositados nas encostas e planícies da fazenda Vão do Buraco, calha do Contagem, porção leste do Planalto Central, na região do Distrito Federal. Foram definidas três encostas: côncava fechada (E1), côncava aberta (E2) e convexa (E3), para a aquisição de dados dos perfis de GPR, onde já se tinham descrições prévias dos materiais depositados, apresentando elúvio no topo, colúvio na média encosta e colúvio/aluvião na planície com formação de um leque aluvial. Fez-se uso de uma antena de 400 MHz para a sondagem, resultando em radargramas com informações de refletância. Devido às diferenças de composição entre o aluvião e o coluvião, seus contatos são abruptos. O alúvio, por apresentar cascalhos em sua composição, é definido por um número maior de alvos e alta refletância. Já o colúvio é constituído por materiais de granulometria mais fina (silte e argila), apresentando baixa refletância com alvos difusos.
Publisher: Revista Brasileira de Geografia Fisica
Date: 13-12-2020
DOI: 10.26848/RBGF.V13.07.P3498-3517
Abstract: Este trabalho teve como objetivo reunir informações sobre comportamento pedogenético e hidrológico em áreas de rochas carbonáticas de clima tropical. A execução desta pesquisa foi embasada em artigos científicos indexados, nacionais e internacionais, como também em livros, teses e dissertações relevantes para o tema proposto. O solo é um sistema multifásico, e os seus aspectos morfológicos e constitucionais atuam facilitando ou dificultando a permeabilidade da água, assim cada horizonte pedológico funciona como um mecanismo em um mesmo perfil de solo. Os fatores físicos/químicos da água também atuarão contribuindo para a classificação dos grupos hidrológicos de solo. No Brasil, a Embrapa realizou classificações dos horizontes diagnósticos, dos grupos hidrológicos e dos tipos de solos, baseada em autores internacionais, adaptadas às condições tropicais. Mas as áreas cársticas, que representam um percentual de 20% da superfície terrestre, podem apresentar condições particulares para a formação de solo e para o comportamento hidrológico, podendo incluir zonas locais de alta permeabilidade, fuga de água subterrânea e eliminação de resíduos insatisfatórios. Solos de ambientes cársticos são mal desenvolvidos, apresentam argilas avermelhadas de baixa atividade normalmente. No Brasil os estudos deste tipo de ambiente são escassos, mas alguns trabalhos desenvolvidos em áreas cársticas trazem algumas informações básicas sobre os solos. As pesquisas encontradas que trouxeram informações dos solos em carstes, foram plotadas no mapa brasileiro. A pesquisa demonstrou que há um gap de informações para o desenvolvimento pedológico em áreas cársticas, mas é possível fazer associações entre estas classes de solo a outros ambientes, incluindo o comportamento hidrológico.Soils In Tropical Karst, Pedogenetic Development And Hydrological Behavior: A Theoretical Review A B S T R A C TThis work aimed to gather information on pedogenetic and hydrological behavior in carbonate rock areas of tropical climate. The execution of this research was based on indexed scientific articles, national and international, as well as on books, theses and dissertations relevant to the proposed theme. The soil is a multiphase system, and its morphological and constitutional aspects act to facilitate or hinder water permeability, so each pedological horizon works as a mechanism in the same soil profile. The physical / chemical factors of the water will also act contributing to the classification of soil hydrological groups. In Brazil, Embrapa carried out classifications of diagnostic horizons, hydrological groups and soil types, based on international authors, adapted to tropical conditions. However, karst areas, which represent a percentage of 20% of the earth's surface, may present particular conditions for soil formation and hydrological behavior, and may include local areas of high permeability, groundwater leakage and unsatisfactory waste disposal. Soils in karst environments are poorly developed, with reddish clays of low activity normally. In Brazil, studies of this type of environment are scarce, but some studies carried out in karst areas bring some basic information about the soils. The researchers found that brought information on soils in carstes, were plotted on the Brazilian map. Research has shown that there is an information gap for pedological development in karst areas, but it is possible to make associations between these soil classes and other environments, including hydrological behavior.Keywords: Soil Hydrological Groups Tropical Soil Karst.
Publisher: Instituto de Geociencias - UFRJ
Date: 13-05-2019
Publisher: The Research Center of the Slovenian Academy of Sciences and Arts (ZRC SAZU)
Date: 08-12-2022
Abstract: Doline mapping is paramount in the vulnerability and risk assessment of the underground karst environment by identifying cave-ground connectivity points at the surface. However, manual mapping is labour-intensive, slow and subjective, especially on a large scale. Therefore, the present study adopted a GIS-based semi-automatic approach for mapping large and medium-sized depressions/dolines in the Corrente river basin in Brazil, with a particular focus on the environmentally preserved areas of river Vermelho (APANRV Portuguese abbreviation) using remote sensing (DEM and Google Earth imagery) and field-based observations. Seven typical dolines forms (e.g., cockpit with drain insertion, collapse, collapse with river capture, suffosion, solution, cover collapse, and buried) are found from extensive field surveys. As an outcome of the proposed approach, two hundred and thirty-two medium to large-sized dolines have been identified and categorised into three main groups based on the cave density and local geology G1, G2, and G3. The high density of identified dolines (164 known caves) in G1 provides reconnaissance for future speleological works in the preserved areas. Additionally, the presence of a considerable number of dolines in the adjoining areas (G2 and G3) stresses the need to revise the existing boundaries of the APANRV. Results correlate well with the dolines sites marked using field surveys and Google Earth images. This doline mapping may help researchers in the groundwater vulnerability assessment and the protection of speleological heritage preserved in the caves.
Publisher: FapUNIFESP (SciELO)
Date: 09-2019
Publisher: MDPI AG
Date: 28-02-2022
DOI: 10.3390/APP12052509
Abstract: The present study applies a geophysical approach to the Federal district of Brazil, a challenging hydrogeologic setting that requires improved investigation to enhance groundwater prospecting to meet the rising water demand. The geophysical characterization of a complex hard-rock aquifer sub-system was conducted using direct current (DC) electrical resistivity tomography (ERT) integrated with surface geological information. With a total of twenty-seven ERT profiles, the resistivity acquisition was carried out using a dipole-dipole array of electrodes with an inter-electrode spacing of 10 m. Based on resistivity ranges, the interpretation of the inverted resistivity values indicated a ground profile consisting of upper dry soil, saprolite, weathered, and fresh bedrock. Along with this layered subsurface stratigraphy, the approach allowed us to map the presence of significant hydrogeological features sharp contrasting anomalies that may suggest structural controls separating high-resistivity (≥7000 Ω m) and low-resistivity ( Ω m) conducting zones in the uppermost 10 m of the ground. The assumed impacts of these features on groundwater development are discussed in light of the Brasilia aquifer settings.
Publisher: MDPI AG
Date: 12-10-2020
DOI: 10.3390/W12102835
Abstract: Reliable characterization of the karst system is essential for risk assessment where many associated hazards (e.g., cover-collapse dolines and groundwater pollution) can affect natural and built environments, threatening public safety. The use of multiple geophysical approaches may offer an improved way to investigate such cover-collapse sinkholes and aid in geohazard risk assessments. In this paper, covered karst, which has two types of shallow caves (vadose and fluvial) located in Tarimba (Goias, Brazil), was investigated using various geophysical methods to evaluate their efficiency in the delineation of the geometry of sediments filled sinkhole. The methods used for the investigation were Electrical Resistivity Tomography (ERT), Seismic Refraction Survey (SRS), Seismic Refraction Tomography (SRT) and the Very Low Frequency Electromagnetic (VLF-EM) method. The study developed several (2D) sections of the measured physical properties, including P-wave velocity and electrical resistivity, as well as the induced current (because of local bodies). For the analysis and processing of the data obtained from these methods, the following approaches were adopted: ERT inversion using a least-square scheme, Karous-Hjelt filter for VLF-EM data and time-distance curves and Vp cross-sections for the SRS. The refraction data analysis showed three-layered stratigraphy topsoil, claystone and carbonate bedrock, respectively. The findings obtained from ERT (three-layered stratigraphy and sediment-filled doline), as well as VLF-EM (fractured or filled caves as a positive anomaly), were found to be consistent with the actual field conditions. However, the SRS and SRT methods did not show the collapsed material and reached the limited the depth because of shorter profile lengths. The study provides a reasonable basis for the development of an integrated geophysical approach for site characterization of karst systems, particularly the perched tank and collapse doline.
Publisher: Sociedade Brasileira de Quimica (SBQ)
Date: 2013
Publisher: MDPI AG
Date: 14-08-2020
DOI: 10.3390/W12082289
Abstract: The use of geophysical characterization of karst systems can provide an economical and non-invasive alternative for extracting information about cavities, sinkholes, pathways for water infiltration as well as the degree of karstification of underlying carbonate rocks. In the present study, three geophysical techniques, namely, Ground Penetrating Radar (GPR), Electrical Resistivity Tomography (ERT) and Very Low Frequency Electromagnetic (VLFEM) methods were applied at three different locations in relation to fluvial karst, which is listed as an environmentally sensitive area in Rio Vermelho, Mambaí, Goiás, Brazil. In the data acquisition phase, the GPR, direct-current (DC) resistivity and VLFEM profiles were obtained at the three locations in the area. Data were analyzed using commonly adopted processing workflows. The GPR results showed a well-defined lithology of the site based on the litude of the signal and radar typologies. On the other hand, the inverted resistivity cross-sections showed a three-layered stratigraphy, pathways of water infiltration and the weathered structures in carbonate (Bambui group). The interpretation of VLFEM as contours of current density resulted from Fraser and Karous–Hjelt filters, indicated the presence of conductive structures (high apparent current density) that might be linked to the weathered carbonate and other conductive and resistive anomalies associated with the water-filled and dry cavities (cave), respectively. The results encourage the integrated application of geophysical techniques such as the reconnaissance for further detailed characterization of the karst areas.
No related grants have been discovered for Rogério Uagoda.