This research assessed the efficacy of deep segmentation in identifying and measuring natural karst depressions in the Bambuí Group's carbonate rocks in Western Bahia, Brazil. The investigation used ...five Global Digital Elevation Models (DEMs) with 30-m resolution: Advanced Spaceborne Thermal Emission and Reflection Radiometer - Global Digital Elevation Model version 3 (ASTER-GDEM v3), Advanced Land Observing Satellite World 3D – 30 m version 3.2 (AW3D30 v3.2), Copernicus 30 m global DEM (GLO-30), NASA Digital Elevation Model version 1 (NASADEM v1), and Shuttle Radar Topography Mission version 3 (SRTM v3). The karst feature detection analysis compared five semantic segmentation architectures: Feature Pyramid Networks (FPN), LinkNet, UNet, UNet++, DVL3+, using an EfficientNet-B7 backbone, one instance segmentation model (Mask-RCNN), and a semantic-to-instance conversion method. This comparison considers different datasets, including one, two, or eleven variables (DEM, DEM-based sink depth, and nine terrain attributes). Besides, we performed a combinatorial analysis of the DEMs to evaluate the improvement in karst feature detection. The methodology involved the generation of geomorphometric attributes, sample labeling from Sentinel-2 and Operational Land Imager-Landsat 8 datasets, training-validation-testing steps with 128 × 128 samples, reconstruction of large images for semantic and instance segmentation, and accuracy analysis. The findings revealed that GLO-30 and AW3D30 data were the most accurate, while ASTER GDEM performed poorly in both segmentation forms. Among the semantic models, FPN showed the highest accuracy. The 11-variable models preferentially outperformed those with fewer in both types of segmentation. The approach of semantic-to-instance conversion with Geographic Information System tools favored individualizing karst depressions and obtaining efficient quantification, consisting of an easy alternative to achieve instance segmentation. Reconstruction of large remote sensing images through sliding windows considering the specifics of instance and semantic segmentation demonstrated that smaller stride enhances object coverage and reduces the risk of losing crucial information, effectively improving the predictions. The combinatorial analysis for semantic and instance segmentation indicates that models incorporating more DEMs (4- and 5-DEM models) and variables achieve generally higher accuracy. The best result in semantic segmentation was combining the five DEM datasets using 11 variables, reaching an F-score of 85.06 and IoU of 74.00. In instance segmentation, the best result for the bounding box was the model that integrates AW3D30, GLO-30, NASADEM, and SRTM with eleven variables reaching Average Precision (AP) of 45.64, AP50 of 88.40 and AP75 of 39.38, while the best result for the segmentation mask was the model that integrates the five models with eleven variables with AP of 42.61, AP50 of 86.79 and AP75 of 35.43. These results demonstrate that integrating a wide range of DEM data, even the lowest performing ones, improves model generalization and accuracy in segmentation, leveraging strengths and mitigating individual weaknesses. Future work could explore high-resolution DEMs and the integration of various deep-learning methods.
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•First deep segmentation investigation for karst depression detection in Brazil.•Copernicus Digital Elevation Model with 30-m resolution achieved superior accuracy.•Feature Pyramid Network was more accurate model in detecting karst depressions.•Combining digital elevation model with morphometric attributes improves accuracy.•Successful quantification using semantic-to-instance segmentation conversion.
Despite increasing knowledge on the orogenic phases of the Pyrenees, the Neogene evolution of the range remains poorly constrained. The central Pyrenees, particularly the Ariège River valley and its ...terrace systems and glacial extensions, are key to reconstructing Pyrenean evolution during the Neogene. However, few terrace relics remain on the piedmont edges. To overcome this limitation and temporally extend the dataset obtained from terraces, we focus on alluvium-filled horizontal epiphreatic passages developed in limestone karstic networks. These landforms record the transient position of former local base levels during the process of valley deepening, similar to fluvial terraces. The alluvium fills of the studied caves in the Tarascon-sur-Ariège area, in the transition zone between the upper range and the piedmont, therefore enable the reconstruction of the geodynamic evolution of the Ariège River valley. All studied caves are developed on at least eight levels. Based on burial durations determined by 26Al/10Be and 10Be/21Ne terrestrial cosmogenic nuclide dating of samples from epiphreatic levels, our results indicate Langhian to Messinian (~13–5 Ma) incision rates averaging 48 m Myr−1. However, the obtained record does not allow us to accurately retrace the Pliocene evolution of the area due to the lack of known caves at corresponding levels. Moreover, raised local base levels during glacial phases both make the record more complex and call into question the methodological approach in terms of potential internal sediment remobilization and mixing related to implied re-flooding periods.
•We identify eight regional cave levels in a Neogene valley in the eastern Pyrenees.•26Al/10Be, 10Be/21Ne burial durations obtained for intrakarstic alluvium.•Langhian-Messinian valley incision rates were ~48 m Myr−1.•Palaeodenudation rates increased by one order of magnitude since the Miocene.•Cave re-flooding events preclude a post-Pliocene reconstruction of the Ariège valley.
Terrestrial laser scanning (TLS) is increasingly used in geomorphology for the study of medium- to small scale landforms. A light weight, compact and portable TLS device has been used in the Grotta A ...Cave (Mt. Lessini, N Italy) to make a detailed 3D model of the underground environment. A total of 16 scans were used to survey the about 150m long cave in <6h. The 3D model of the cave walls makes it possible to carry out morphometric measurements on the different cave environments. The TLS data allowed us to calculate cave volumes and distinguish cupola, phreatic conduit and basalt dike volumes. Wall roughness analysis also allowed recognising smaller-scale morphologies such as megascallops, differential corrosion forms and mineral crusts. These observations have enabled us to discern between different karstification processes and speleogenetic phases, highlighting the importance of condensation-corrosion on the cave passage enlargement in a quantitative way.
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•Terrestrial laser scanning has been used to survey morphologies in a cave.•TLS data have been used to make volumetric calculations of cave voids.•TLS point clouds allow to distinguish cave wall macro- and micromorphologies.•Different cave morphologies are related to successive speleogenetic stages.•Condensation-corrosion processes are very important in shaping the cave voids.
The Cordillera de la Sal (CDS) is a NNE-SSW elongated fold-and-thrust belt several km wide and over 100 km long located in the hyper-arid climate of the Atacama Desert. This ridge contains important ...Oligocene-Miocene continental sediments including thick interbedded salt rock units which form extensive outcrops. Despite the rare occurrence of rain events, these salt rock beds host well-developed and scientifically interesting underground cave systems, perfectly adapted to the contemporary drainage network. The complete lack of vegetation makes this area a perfect analogue to extraterrestrial evaporite karst areas. A remote sensing analysis of 600 km2 of Pleiades images (acquired in 2018 by courtesy of European Space Agency) at a spatial resolution of 0.5 m (panchromatic) and 2 m (RGB and near-infrared bands) and DTMs extracted from stereographic couples has allowed to map the lithological units, the drainage network, and the candidate cave entrances (CCEs) of most of the Cordillera de la Sal.
The study area has been divided in eight morpho-structural units, based on our geological and geomorphological mapping. An Analytic Hierarchy Process (AHP) was used to classify the CCE potential of these karst zones into four classes: low, medium, high, and very high potential of finding new caves. This remote-sensing derived CCEs inventory has been ground truthed with two testing datasets (101 points): i) confronting the cave register based on explorations carried out prior to this analysis, and ii) with a field-based validation in completely unexplored areas. These ground-truthing methods support the quality and reliability of our remote sensing-derived CCEs, with accuracies of 71% and 83%, respectively.
With this integrated remote-sensing and ground-truthing approach, we highlight that CCEs identification by image analysis and GIS processing appears reliable for speleological explorations in the CDS and might be a valuable tool also for objective decision-making in the search of caves and potential areas susceptible to karst formation on other planetary bodies.
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•Pleiades image processing allowed to map salt rock outcrops in the Cordillera de la Sal.•Candidate cave entrances (CCEs) have been identified using remote sensing techniques.•Analytical Hierarchic Process (AHP) multicriteria analysis was performed to evaluate the CCE speleological potential.•The remote sensing derived CCEs have been verified with ground-truth data.•This remote sensing workflow is particularly reliable in identifying CCEs.
The Houping Tiankeng cluster is a part of the South China Karst UNESCO World Natural Heritage Site. Within the distinctive Wulong plateau-gorge karst, >200km of cave passages have been documented to ...date. This paper focuses on detailed tectonic and morphological research on the Luo Shui Kong cave, enriched with U-series dating of speleothems and complemented by morphometric analysis of the San Wang Dong and Er Wang Dong caves. All of these caves exhibit three regional levels of cave development: 1) 1040–1020m a.s.l.; 2) 900–840m a.s.l.; and 3) 740–660m a.s.l. The Houping Tiankeng area is a carbonate rock sequence several hundred meters thick, overlain by the less soluble Lower Ordovician strata, limiting recharge points to faults exposing underlying easily soluble formations. This leads to the domination of concentrated, high-volume inflow and thus results in caves of large volume in the plateau-gorge karst. Shafts connecting the surface with cave passages located underneath formed along faults, changing the hydrogeological pattern through karst water capture and remodeling of existing conduits, albeit mainly by increasing their overall dimensions rather than by deepening them. The most favorable structures for cave-level development are two sets of joints conjugated with gently inclined bedding. Since these joints are characterized by a small vertical extent, downward development is limited. Hence, most of the passages are wide but not deep canyons and typical of a water-table cave pattern. Places where the fault plane is eroded from the surface and where, at the same time, an underneath cave chamber ceiling expands upwards are particularly predisposed to the formation of a tiankeng.
•Tectonics, morphology and morphometry of the Luo Shui Kong cave were studied.•Three regional cave levels have been identified: 1040–1020, 900–840, 740–660m a.s.l.•Concentrated flow in the plateau-gorge karst forms caves of large volume.•Tiankengs develop when faults eroded from the surface meet caves underneath.
The karst landscape is widespread in the southern region of China. As a result of underground mining activities, the original stress equilibrium is disrupted, causing the redistribution of stress in ...the overlying rock layer, inducing the longitudinal fracture of mining to expand and penetrate upwards, resulting in the rupture and destabilization of the karst cave roof, thus triggering a series of engineering problems such as karst cave collapse, landslide, the discontinuous deformation of the ground surface, and soil erosion. In order to study the evolutionary characteristics of buried rock fissures in shallow coal seam mining under the karst landform, taking the shallow coal seam with the typical karst cave development landform in Guizhou as the engineering background, based on the similarity simulation experiment and fractal theory, the evolution law of buried rock fissures and network fractal characteristics under the disturbance of the karst landform mining are analyzed. The research shows that the mining-induced fracture reaches the maximum development height of 61 m on the left side of the cave, and the two sides of the cave produce uncoordinated deformation. The separation fracture below the cave is relatively developed, and the overall distribution pattern of the cave rock fracture network presents a “ladder” shape. The correlation coefficient of the fractal dimension of the rock fractures under different advancing distances is more than 0.90, and the rock fracture network under the karst landform has high self-similarity. The variation of fractal dimension with the advancing degree of the working face can be divided into four stages. The first and second stages show an exponential growth trend, and the third and fourth stages show linear changes with slopes of 0.0007 and 0.0014, respectively. The fluctuation of the fractal dimension is small. The periodic weighting of the upper roof in the cave-affected zone is frequent, the fragmentation of the fractured rock mass becomes larger, and the fractures of the upper rock mass are relatively developed. The research results can provide a reference for the study on the evolution law of mining-induced rock fissures under similar karst landforms.
The analysis of paintings and engravings on the walls of Upper Palaeolithic caves generally focuses on the images themselves, their technical or stylistic characteristics, graphical and spatial ...composition, and, to a lesser extent, radiometric dating. More recent studies of cave art have reinforced new interdisciplinary perspectives that address the archaeology, karstology and geomorphology of the site. This latter aspect helps place the representations in the long-term geo-morphological history of the cave itself, and thus sheds new light on its human occupation. At the Grotte du Mammouth (Domme, Dordogne, France), we developed an innovative approach to cave art that incorporates a geological and geomorphological analysis of the decorated walls combined with new mapping and digital recording techniques to produce a detailed “identity card” of the site's features.
•An innovative and integrated archaeological and geomorphological method to map the parietal art.•Detailed catalogue of karstic features available in the Grotte du Mammouth to compare archaeological and geological markers.•Identification of karstic features associated with each panel to interpret certain graphic entities or to clarify others.•Combining geological and archaeological data to distinguish natural processes from cave art on the walls.•A relative chronology of most natural phenomena regarding the anthropogenic representations.•The cave walls shapes, sediments and chemical deposits used in order to retrace the cave wall history over the long term.
Kayen District, Pati Regency is a karst morphology area composed of karstified limestone with geotourism potential, established as Karst Landscape Area. As basis for infrastructure development in ...geotourism area, a database of geosites need to be built to make sure it is available for government and public. The method used is field observation, interviews and SWOT analysis. Morphology of this area is divided into conical karst hills and the karst alluvium plains. The lithology of the research area are reef limestone, clastic limestone, and alluvial deposit. Inventory managed to identify potential geosites such as hills, cliffs, caves, and springs; five existing geosites have been developed and six locations are new geosite recommendations. From the SWOT analysis, it is known that this location has the strength that is the uniqueness of morphology from karstification results, the weakness is geotourism concept is still not yet understood by local residents, the opportunity is the minister's decision regarding the Sukolilo Karst Landscape Area and the threat is lack of geological protection at the research site. The geotourism and geotrack map will serve as geospatial information and further recommendation for government to prioritize the infrastructure development in this area.
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