Coastal erosion is a relevant concern along the semi-arid coast of Northeastern Brazil, where tide-modified mixed siliciclastic–carbonate beaches exhibit seasonal variability and increasing anthropogenic pressure. This study aims to analyze the seasonal sedimentary dynamics of Peroba and Picos beaches, located in Icapuí, Ceará. Sediment samples were collected during four field campaigns, in March, May, September, and November 2024, and analyzed for grain-size distribution, calcium carbonate content, and sediment classification. The results indicate a predominance of very fine to fine sands on both beaches, with Peroba showing lower grain-size variability throughout the analyzed period and Picos exhibiting more pronounced spatial and seasonal variability. Calcium carbonate was higher for the backshore of Peroba, with a mean of 71.5%, while Picos showed greater fluctuations, especially in specific sectors and field campaigns. Sediment classification indicated the predominance of fine to very fine lithoclastic and lithobioclastic sands in Peroba, whereas Picos showed greater sedimentary class diversity, with up to ten distinct classes, including bioclastic and mixed classes. These results indicate distinct morphosedimentary responses between the two beaches, associated with seasonality, hydrodynamics, sediment availability, and local morphosedimentary controls. Finally, the importance of integrated sedimentological analyses and continuous monitoring is emphasized to improve the understanding of sediment sources, transport processes, seasonal redistribution, and long-term coastal evolution.
This study investigates planation surfaces and the dynamics of river divides in Northeast Brazil, with a focus on the Chapada do Araripe region. The research integrates morphometric metrics and regional geological interpretation to understand the processes that shape the evolution of the relief through the migration of divides and the interposition of planation surfaces. Geomorphometric metrics based on a digital elevation model (including TPI, Ksn, χ index, and Gilbert metrics) were applied, and three main surface levels were identified: S1 (>710 m), S2 (485–710 m), and S3 (<485 m), which reflect distinct stages of pediplanation since the Cretaceous. The analysis reveals that the preservation of these surfaces is strongly conditioned by structural, lithological, and climatic factors. Additionally, the results indicate variations in the stability of the river divides among the Parnaíba, Jaguaribe, and São Francisco basins, with a tendency toward migration on the Jaguaribe-São Francisco and São Francisco-Parnaíba divides, associated with fluvial reorganization processes. This work proposes an evolutionary model for the region's landscape, highlighting the interactions among tectonic heritage, differential erosion, and climate change over geological time.
The Pantanal wetland, located in the Upper Paraguay River Basin, is the world's largest tropical wetland and a key region for understanding fluvial system responses to Late Quaternary climatic changes. This study investigates the geomorphological evolution of the Paraguay-Corumbá Fluvial Plain (PCFP; approximately 18.3°S to 19.4°S and 57.0°W to 57.8°W) using remote sensing, sedimentological analysis, and OSL dating. We identified three main geomorphological compartments: (1) a floodbasin with topographically elevated channels; (2) an abandoned meander belt; and (3) the active meander belt (floodplain) of the Paraguay River. Sedimentary and chronological data indicate that the floodbasin and its topographically elevated channels developed prior to the Last Glacial Maximum (>23 ka), under conditions of high sediment supply and variable discharge. A meandering system (paleomeander belt) was active during the late Pleistocene to early Holocene (ca. 10–9 ka OSL), with its initial formation possibly occurring earlier under wetter late Pleistocene conditions. A final avulsion event near Castelo Bay around 2–1.5 ka resulted in the current meander belt. These changes reflect primarily variations in hydro-sedimentary dynamics, likely driven by regional climatic shifts during the Late Quaternary. Our results provide new insights into the complex evolution of large tropical floodplains and highlight the role of sediment supply and discharge regimes in controlling fluvial style in the Pantanal.
Gullies in urban environments pose challenges to urban land-use planning due to their rapid development and the impact they cause on infrastructure and the physical environment. This study aimed at monitoring four gullies located in Colônia Antônio Aleixo watershed, in Manaus, Brazil, to analyze their morphometric characteristics and to estimate associated erosion rates. The study was based on cartographic records from 2006, 2012, and 2016, complemented by Unmanned Aerial Vehicle (UAV) surveys conducted in 2017 and 2020. The high-resolution imagery provided detailed information on the erosive features, while fieldwork supported data validation. The results indicate widening of the gullies and reduction in their depth, due to internal sediment deposition. Edge retreat also led to the coalescence of adjacent features. UAV monitoring made it possible to identify secondary landforms associated with reworking processes, such as headcut alcoves and small erosional channels. It is concluded that topographic profile analysis is an effective approach for understanding the morphology and evolutionary dynamics of gullies in urban environments.
The analysis of morphometric parameters has been widely employed to assess flood susceptibility; however, at broader scales, it tends to homogenize and generalize results, concealing relevant local differences. This study aims to investigate flood susceptibility using fifteen morphometric parameters in a GIS environment, at scales ranging from basins and sub-basins up to the sixth order, located in the northern Mantiqueira range/coastal plain of Espírito Santo, Brazil. The methodological approach enabled comparative analyses and a more detailed assessment of morphometric susceptibility, while also providing a more consistent regional comprehension. Additionally, the results were related to the rainfall regime using the CHELSA 1.2 global precipitation model, which allowed for the identification of more critical sub-basins. The analyses highlight the relevance of parameters such as area, altimetric amplitude, perimeter, and main channel slope in defining areas more susceptible to flooding. In mountainous and small-sized basins, such characteristics may be more determinant than precipitation itself in intensifying surface runoff. The sub-basin level analysis revealed local susceptibility patterns, emphasizing the concentration of critical areas in the middle and lower courses of the Santa Maria River basin and the widespread distribution in the Jucu River basin, as well as the asymmetry observed on the right margin of the main channels of both basins.
Forest fires, intensified by human activities, are transformed into environmental disasters and affect biomes that are not naturally adapted to fire, such as the Caatinga. With the advent of climate change and the increasing number of fires, it becomes necessary to understand their impact on surface environmental dynamics, including sedimentological processes. One way to analyze these changes is through sediment connectivity, which refers to the physical linkages that enable the potential transfer of sediments across the landscape. Therefore, this study aims to analyze the impacts of fire through sediment connectivity, using remote sensing imagery from before and after the fire events and applying connectivity and vegetation indices. The results show a 14% increase in connectivity values in the study area, which is proportional to the fire's intensity. Vegetation indices indicate a slow recovery of the area. Finally, limitations were observed in the use of proposed roughness input values for burned areas, as well as in the natural recovery capacity of the Caatinga, which, even after four years, had not returned to pre-fire levels.
The geomorphological mapping of the state of Mato Grosso is presented, integrating theoretical and methodological perspectives of geomorphometry, the history of local geomorphological cartography and discussions within the scope of the SBCR. A hierarchical classification was established in four taxons with morphological emphasis (macro landforms, morphostructures, landform units and landform patterns), whose mapping parameters were based on geomorphometric attributes. The proposal focused on the semantic issues used to express the conceptual (qualitative) models of landforms and the classification parameters (quantitative) linked to geometry and morphological homogeneity. The Copernicus DEM and the geomorphometric attributes of mean slope, altimetric amplitude, topographic position index and white top hat were used. The 1st taxon was classified as plateaus, plains, lowlands and mountains. In the 2nd taxon, sedimentary basins, orogenic systems and cratons were mapped. The 3rd taxon resulted in 67 landform units and the 4th taxon indicated a new subdivision into 16 landform patterns. Considering the integration of the four hierarchical levels, 376 landform classes were mapped in the state of Mato Grosso. It is concluded that the combination of local and focal geomorphometric attributes was successful in generalizing and distinguishing morphologies in terrains with varied characteristics and dissections.
On Thursday, February 8th, 2024, a subaqueous slope failure occurred adjacent to the sand spit terminus at Puntarenitas, Puerto Jiménez, Costa Rica, whereby sediments were mobilized from a nearshore area encompassing approximately 410 m² of beach front. Investigation procedures included salinity, temperature, and density profiling at multiple stations, complemented by underwater videography. Additionally, photogrammetric mosaics were generated through Unmanned Aerial Vehicle (UAV) surveys, and a bathymetric map was constructed using echosounder data. The failure event was characterized by a primary headscarp and three secondary scarps exhibiting a succession of a stepped-like configuration that extended into the subaqueous zone. The submarine failure surface displayed a concave convergent morphology with a proximal sediment accumulation adjacent to the landslide. Morphological and kinematic analysis of the event indicates that it represents a Retrogressive Breach Failure mechanism. These processes are relatively rare yet recurrent at specific locations, as was corroborated through satellite imagery analysis, thereby constituting a natural hazard requiring measures to prevent future risk generations.
Landslides represent one of the major socio-environmental risks worldwide, with socio-economic impacts intensified by unequal urbanization and the increasing frequency of extreme events associated with climate change. In this context, monitoring and early warning systems based on low-cost sensors emerge as a strategic alternative to expand the coverage and accessibility of these technologies, particularly in areas with poor or inadequate infrastructure. This paper presents a Systematic Literature Review (SLR), conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, aiming to analyze the state of the art of such systems. The search was carried out in the Scopus and Web of Science databases, considering articles published between 2020 and 2025, resulting in a final selection of 69 studies. Bibliometric, thematic, and qualitative analyses made it possible to identify application contexts, employed technologies, and criteria adopted for defining low cost. The results indicate a predominance of studies associated with intense rainfall events, the integration of in situ sensors, the Internet of Things (IoT), and applications in mountainous rural areas, as well as the emerging use of digital twins as a strategy for multiscale synthesis and predictive support. It is concluded that low-cost solutions have a high potential to democratize early warning systems, although challenges related to calibration, reliability, and durability remain.
The uprush and backwash of a wave (swash climate) at the beach face, as well as the duration of this process, depend not only on wave characteristics such as height and period, but also on the beach-face slope, which in turn is partially conditioned by the sediment grain size. As a general trend, the coarser the grain size, the steeper the slope, and faster the uprush and backwash cycle (swash regimen) is completed. This cycle is partially related to the morphodynamic characteristics of a beach, passing through dissipative, intermediate, and reflective stages as the beach face slope increases. Observational data along the beaches of the Doce river delta, Espírito Santo - Brazil, showed a correlation between beachface slope, morphodynamic state and swash regimen, with some variations along the study site. Dissipative and saturated swash regimen were related to beach face slopes lower than 3°, while the reflective stage and more complete swash regimen were related to slopes higher than 5.5°. The flow regimen of extreme states often shifts from dissipative or reflective to intermediate morphodynamic state and vice-versa. The results herein provide an objective physical framework to morphodynamical comparative studies and potential implication for benthic ecological studies.
Suspended sediment concentration (SSC) plays a fundamental role in the hydrological and geomorphological processes of large tropical rivers. However, SSC monitoring remains limited in the Amazon Basin, particularly in the Negro River, one of the largest rivers in the world. This study develops and validates an empirical model to estimate SSC in the middle Negro River (Amazon Basin) using MODIS surface reflectance data and in situ measurements and proposes a long-term reconstruction of SSC for the region. The results indicate that the Ordinary Least Squares (OLS) regression model presented the best statistical performance. The reconstructed time series from 2003 to 2024 revealed a low average SSC (~5 mg L⁻¹) and a statistically significant negative trend (−0.0536 mg L⁻¹ year⁻¹). The results demonstrate that MODIS data can be successfully applied to SSC monitoring in blackwater rivers despite spectral limitations. The study indicates that, despite the negative trend associated with low SSC availability and current geomorphological dynamics, the middle Negro River remains stable. This study contributes to advancing the application of remote sensing in optically complex environments and to improving the understanding of geomorphological processes in large tropical rivers dominated by sediment limitations.
Geodiversity, as the abiotic variety of nature, provides the foundation for identifying geoheritage elements. Roraima, located within the Guiana Shield, exhibits high geodiversity but lacks regional-scale quantification studies. This study aimed to quantify geodiversity along the BR-174 corridor and identify priority areas for future geosite inventories. The geodiversity index method was applied using GIS, analyzing class richness of lithology, geomorphology, and pedology on a 15 × 15 km grid classified by the Jenks natural breaks method. Results revealed a heterogeneous distribution, with 37% of the area classified as "high" and "very high", concentrated in the central region (Caracaraí, Iracema, Mucajaí, Amajari). A total of 67% of previously cataloged geological interest points coincided with these areas. We conclude that the index is an effective tool for regional-scale geoheritage prospecting, and the sectors mapped as priority along the BR-174 represent targets for future investigations, supporting geoconservation policies and territorial planning.
The objective of this article was to carry out a geomorphological study of Topocalma's dune field through a photogrammetric survey using a drone, a methodology that has not been used to study dune fields in Chile. As a system with little intervention, the selection of the area particularly lies in the lack of further dune field geomorphological investigation. However, adjacent areas present relevant anthropogenic pressures; therefore, the use of new methodologies could contribute to its conservation and preventive planning. A dense point cloud, a digital elevation model and, an orthomosaic were obtained from an aerial photogrammetric survey carried out with a UAV. Subsequently, a morphometric characterization is carried out based on the height, slope and orientation of shapes, to generate a 3D model and a geomorphological map. The beach morphology and the formation of protodunes (bedform) of these last products were identified, when receiving a greater supply of sand form barchans, barchanoids and transverse dunes. Hence, a transgressive dune field was configured, which evolved towards an akl & eacute; pattern and parabolic dunes, at the same time.
Digital elevation model (DEM) with a resolution of 9.48 cm/pixel and an orthomosaic with a resolution of 2.37 cm/pixel of the active dune field of Topocalma https://data.mendeley.com/datasets/trgcnr8wv9/1
This study examined the ice phenology of twenty-five lakes located in the Fildes and Keller peninsulas (King George Island) and the Byers Peninsula (Livingston Island), Antarctica, using SAR (Sentinel-1) data from 2014 to 2023. A backscatter threshold was established for ice-free and frozen surfaces in S1 images. The temporal analysis of lake phenology was conducted covering the months from October to March. The slope context, altitude, and distance from the coast of the lakes were characterized. Field activities were carried out to validation. Temporal backscatter analysis revealed seasonal patterns of lake surface freezing and thawing, which were correlated with climatic variables, including mean air temperature, precipitation, and wind. Mean air temperature emerged as the primary driver of ice cover variability, with fewer frozen days observed in years of increased positive temperatures, particularly during El Ni & ntilde;o events. The years 2015 and 2019 exhibited less thawing, while 2023 recorded the lowest extent of frozen lake surfaces (99.15%). Local factors, including wind speed and direction, and coast distance and altitude, also influenced the observed patterns. Sentinel-1 imagery proved effective for mapping and monitoring lake surface ice cover in glacial and periglacial environments, underscoring its potential for assessing lacustrine responses to climate variability.
This study analyzed hydrosedimentary dynamics at the confluence of the Beni and Mamoré rivers, the two main source rivers of the Madeira River, the largest tributary of the Amazon River. Thirteen field campaigns were conducted between March 2021 and April 2022 at four cross-sections, complemented by historical data from the HYBAM Observatory. The results showed clear contrasts between the tributary rivers: mean suspended sediment concentrations (SSC) were 639 mg.L⁻¹ in the Beni and 218 mg.L⁻¹ in the Mamoré, with specific yields of 2.07 and 0.34 ton.km⁻².yr⁻¹, respectively. The Madeira River exhibited intermediate SSC values (357–371 mg.L⁻¹). During high-water conditions, vertical SSC stratification was more pronounced in the Mamoré and Madeira rivers. The sediment budget indicated a 15% deficit downstream of the confluence, corresponding to the retention of approximately 40 million tons over a 220 km reach. Downstream of this confluence lies the Jirau Hydroelectric Power Plant reservoir, whose dam may influence the study reach. Together, the Beni and Mamoré rivers contribute about 291 million tons of suspended sediment annually to the Madeira River, confirming their strategic role in the Amazon sediment budget and providing a basis for sustainable management of this watershed’s resources.
The Belo Monte Hydroelectric Complex, located on the Xingu River in Altamira, Pará, Brazil, includes two power plants: Pimental, built directly on the riverbed, and Belo Monte, which uses water diverted from an intermediate reservoir. This reservoir is contained by 28 dikes, mostly underlain by migmatite residual soils. During construction and early operation, tubular cavities known as canaliculi and associated resurgence processes were identified downstream of several dikes. However, the spatial controls governing these phenomena remain poorly understood in tropical lateritic environments. This study proposes an integrated geostatistical–machine learning framework for the spatial prediction of resurgence and canaliculi. Ordinary Kriging was applied to model the elevation of the Young Residual Soil (YRS) contact surface using approximately 450 borehole records. The model was subsequently extrapolated to downstream areas lacking direct subsurface data through Support Vector Machine (SVM) regression. A digital terrain model was combined with the modeled YRS contact to identify potential outcrop zones associated with resurgence. Spatial statistical indicators based on minimum-distance metrics were developed to quantify the correspondence between predicted outcrop areas and fieldmapped occurrences. The results show strong spatial agreement between predicted YRS outcrop zones and mapped resurgence and canaliculi points across five representative dikes, with average shortest distance ranging from 4.4 to 50.6 m. Cross-validation indicated satisfactory predictive performance of the YRS digital model, with RMSE values between 4.16 and 9.56 m for kriging and between 3.36 and 10.65 m for SVM. The proposed framework provides a replicable and cost-effective predictive tool for dam safety management, supporting the definition of priority inspection corridors and early detection of anomalous resurgence and canaliculi behavior in tropical dam foundations.
Quartzite regions tend to present incipient and unconsolidated surface materials, even in areas with humid tropical climates. The degree of weathering of surface materials and its relationship to topography in these environments remains unknown. Therefore, the objective of this study is to analyze the relationship between topography and the mineralogy of the clay fraction of surface materials developed in quartzite bedrock. We selected three representative slopes along which transects were installed from the crest to the valley floor. Nine geocover samples were collected for analysis by X-ray diffraction. The results were analyzed using the Principal Component Analysis method. The results show a correlation between the identified materials, their position on the slope, the slope profile, and the presence of natural barriers. In the first transect, representing a quartzite ridge with extremely incipient weathering material, minerals indicative of highly weathered environments with poor drainage, such as kaolinite and illite, were found. In the second transect, representing broad interfluves with long slopes and low gradients, samples presented Fe and Al oxides and hydroxides, demonstrating the advanced degree of weathering in the area. The third transect, conducted in a secondary divide with a convex profile, collected a deeper sample containing goethite and siderite, indicating a poorly drained environment with water remaining in the system for a short time. Thus, it can be seen that, despite the predominantly quartzite basement, the shape of interfluves and slopes allows for differentiated development of the weathering mantle materials, strongly dependent on drainage dynamics and varying along the slope as a function of changes in longitudinal profiles.
The high average load of suspended sediments in rivers in southern Brazil is related to soil degradation in agricultural areas due to erosive processes resulting from inadequate management. In this context, understanding the dimensions of transported particles and their biogeochemical dynamics is essential, as well as their transport capacity, load, concentration, deposition potential, and degradation within the fluvial system. This study analyzed hydrological characteristics, particle size, and chemical properties (TOC, NT, PT, POrg, Pd) in three river basins in Rio Grande do Sul (2012-2013): Arroio Lajeado Ferreira (1.19 km²), Rio Guaporé (1,980 km²), and Rio Conceição (804 km²), all located in southern Brazil. This research revealed that erosion during heavy rainfall in southern Brazil acts as a selective "geochemical erosion" process, preferentially transporting fine sediments (<63 µm) enriched with nutrients. The dynamics of phosphorus, during intense rainfall events can become predominantly organic (>50%), and quantifying significant loads of bioavailable phosphorus and organic carbon to rivers. The Conceição River Basin stood out with the greatest nutrient loss per area, demonstrating that agricultural practices exacerbate this impact. Suspended sediments (< 63 µm) showed high concentrations of organic carbon, nitrogen, and phosphorus (especially Pd, which is of environmental concern). The particle size D(25), D(50), D(75) did not vary significantly between basins or rainfall events. Phosphorus exhibited a dynamic behavior, at basal flow, it was predominantly inorganic, but during rainfall events, more than 50% could be organic.
Petrographic control has a strong influence on the geomorphological evolution of granitic plutons in the Borborema Province (Northeast Brazil), which are made up of varied natures, shapes and dimensions. The Rio Quixeramobim Batholith, located in the Central Ceará Domain, is conditioned by the dextral shear zones of the NE direction, Quixeramobim and Senador Pompeu and is constituted by six distinct granite suites. This work aims to analyze the geomorphological aspects of the Rio Quixeramobim Batholith, based on petrographic (mineralogical and structural) analyses, correlating the morphologies with the different suites analyzed. The methodology consisted of analysis of geological and geomorphological data, field investigations, sample collection and analysis in a microscopy laboratory. Geomorphological features are strongly related to mineralogical and structural characteristics, associated with the degree of microfracturing of their constituent minerals. The data show that, in addition to mineralogical diversity, structural aspects such as the degree of microfracturing, porosity and texture are fundamental for the development of granitic macro and microforms. Furthermore, the NE-SW trending structural control is also fundamental in the geomorphological diversity, showing an aligned arrangement of inselbergs at the edges of the batholith, as a result of pre-defined structural patterns.
