Geologic Feature Extraction from Remote Sensing Data

Digital Model of Relief (DMR) is a data set of space-structural model of the continental part of the Earth surface, presented in a digital form. It is a subset of spatial and geoinformation systems and presents one of the models of Digital Terrain Model (DTM) which includes different digital models of the Earth crust and the atmosphere. DMR is used for determining, studying (researching) and estimating features of the Earth surface for both military and civilian purposes. It has a multiple application in geodesy amongst which determination of geoid; physical 'reality' of gravity Earth field and determination of the reference surface for orthometric heights-altitudes are of the greatest significance. Orthometric heights are mainly used for applying GPS as well as the common Geocentric Earth Ellipsoid (WGS-84). By applying DMR and Fast Fourier Transform Technique (FFTT) it is a possible to determine geoid ten times more efficient with regard to classical approaches of numerical integration, with possibility of using a large group of data that have broad application. Fundamental terms of DMR, its composition, analysis and the possibility of its application are treated in the paper.

Early recognition of glacial lake hazards in the Himalaya using remote sensing datasets

The article explores the creation of digital terrain models (DRMs) based on dense point cloud classification in QGIS, Digitals, and 3D Survey software. In the research process, a dense cloud of points created during 3D scanning of the territory of the botanical garden of NUBiP of Ukraine was used, followed by classification and construction of digital relief models in various software tools. The stages of point cloud classification, creation of classification layers, data export to QGIS, Digitals and 3D Survey software tools for further modeling and drawing of models with isolines were studied. The digital model of the relief and the stages of its creation, "cleaning" of the original cloud of points of different density are considered. On the basis of the same initial data, a dense cloud of points, the formation of digital models of the relief of the territory of the botanical garden of NUBiP of Ukraine was carried out in various software tools. The process of creating a digital relief model was investigated based on a dense point cloud using QGIS, Digitals, 3D Survey programs. The main advantages and disadvantages of building a digital relief model based on a cloud of points formed by the results of 3D scanning are analyzed. Features and capabilities of software tools QGIS, Digitals, 3D Survey and their ability to build 3D surfaces based on exported point clouds are considered.

<p>The development of erosional features in rockwalls indicate the transition from back-wearing (parallel retreat) erosion to down-wearing by linear dissection. Following Rapp (1960), erosional features such as chutes and funnels are the results of successive undermining rockfalls released by thawing after frost damage. The process doesn’t start from the top of the slope but over a scar leave by a large magnitude rockfall which can appear anywhere on the rock face. Sauchyn et al. (1998) suggest that the type of erosional features (chutes, funnels, open cirques) is under structural control in stratified sedimentary rock. Other, like Dunne (1990), Laity & Malin (1985), Lipar & Ferk (2015) or Duszyński <em>et al.</em> (2016) attributes the development of erosional features and the subsequent development of amphitheatre valley heads to underground erosion by subsurface flow. The presence of perennial spring in erosional features on the flysch rockwalls of the northern Gaspé Peninsula (Eastern Canada) suggest that these notches may be the result of seepage erosion. However, observations show that groundwater seeps out the scar of large magnitude rockfalls. If the location of the spring is conditioned by geological and structural setting, the development of erosional features may as well be under geological and structural control. To support these premises and the development of a conceptual model of erosional features formation, a detailed geological, hydrogeological and climatological characterization was carried out. Meteorological instruments, including temperature probes inserted inside horizontal borehole, were installed directly on a rockwall. Four observation wells were drilled on the plateau above the rockwall and around an erosional features. The hydraulic conductivity was determined using pneumatic slug tests performed every 1.6 meters in the boreholes. The hydraulic gradient was calculated from continuous measurements of the water table using water level logger. An optical borehole televiewer, a three-art caliper probe, an induction conductivity probe and a gamma ray detector were also used to support the geological and structural analysis of the rock mass. A structural analysis was also performed on the surface of the rockwall. The results show that the elevation and the location of the spring on the rockwall is not conditioned by a permeability contrast between geological units, the presence of a perched water table or by a network of interconnected fractures channels water. Our result show that groundwater simply reaches the rockwall surface in the erosional feature. At the periphery of the notch, the hydraulic head decreases significantly in the highly weathered and fractured rock layer near the rockwall surface. Depending on the winter severity, seasonal freeze thaw cycles reaches three to five meters deep into the rockwall. Water seepage and ice formation in the erosion notch maintain the rock temperature above 0<sup>o</sup>C during winter. Large magnitude rockfalls mainly occur in spring after thawing and groundwater supply near the rockwall surface. The initiation and the development of erosional features in flysch formations appear to be controlled through the interaction between groundwater inflow near the surface of the rockwalls and the meteorological conditions that drive frost weathering.</p>

The technical support of the process of creating a cartographic basis for improving the efficiency of territorial management is considered. It is proved that digitalization of information about all management objects is based on the initially implemented stage of preparation of a digital model of terrain and relief. The effectiveness of management decisions depends on the detail and quality of the developed cartographic framework. The authors summarize the practical experience of using innovative technologies in the process of developing a cartographic framework, it is shown that the most promising direction here is the introduction of neural networks. The specifics of their application in the process of creating a digital model of terrain and relief are analyzed.

Fused remote sensing datasets have greatly contributed to enhancing lithological targets and providing significant information for mineral exploration. For instance, multispectral datasets can discriminate rock units through their unique spectral signatures. Digital Elevation Models (DEMs) could be an effective tool boosting lithological discrimination based mainly on their topographic variations. Consequently, the current study applied the power of the support vector machine (SVM) algorithm and the integrated Phased Array L-type band Synthetic Aperture Radar (PALSAR) DEM and multispectral Sentinel 2 data to: 1—Create an updated lithological map of a poorly mapped arid terrain (Khashir-Ras El-Kharit district, Eastern Desert of Egypt), and 2—Compare and assess the distribution of ferrogabbros with the aim of improving the localization of these rock bodies and investigating their mineral content. Our results enhanced the lithological mapping and revealed a better generalization of mineralized ferrogabbros when the input was a fused DEM with Sentinel 2 compared to the salt and pepper effect observed when adopting the Sentinel 2 solely as the input data. Additionally, the current research strongly recommends detailed exploration programs for Fe-Ti oxide ores within the gabbroic rocks delineated through the resultant thematic map. The ferrogabbros were subjected to a comprehensive analysis involving whole rock geochemistry, XRD, EDX, and light-reflecting investigations, which revealed the existence of magnetite, titanomagnetite, and hematite. The titanomagnetite crystals display subhedral morphology and exhibit fine- to medium-grained surfaces with irregular shapes. X-ray diffraction (XRD) analysis revealed the presence of magnetite and hematite in the concentrated Fe-Ti oxides. Additionally, the whole rock geochemistry highlighted the origin of the ferrogabbros and their proposed tectonic setting as an alkaline to calc-alkaline magma type that developed in a continental arc setting.

Lithological mapping is a critical aspect of geological mapping that can be useful in studying the mineralization potential of a region and has implications for mineral prospectivity mapping. This is a challenging task if performed manually, particularly in highly remote areas that require a large number of participants and resources. The combination of machine learning (ML) methods and remote sensing data can provide a quick, low-cost, and accurate approach for mapping lithological units. This study used deep learning via convolutional neural networks and conventional ML methods involving support vector machines and multilayer perceptron to map lithological units of a mineral-rich area in the southeast of Iran. Moreover, we used and compared the efficiency of three different types of multispectral remote-sensing data, including Landsat 8 operational land imager (OLI), advanced spaceborne thermal emission and reflection radiometer (ASTER), and Sentinel-2. The results show that CNNs and conventional ML methods effectively use the respective remote-sensing data in generating an accurate lithological map of the study area. However, the combination of CNNs and ASTER data provides the best performance and the highest accuracy and adaptability with field observations and laboratory analysis results so that almost all the test data are predicted correctly. The framework proposed in this study can be helpful for exploration geologists to create accurate lithological maps in other regions by using various remote-sensing data at a low cost.

Drylands occupy one third of the Earth’s surface and are home to around 400 million people, yet the water resources of these regions are often poorly understood because of a lack of fundamental hydrological data. Rivers are often low-gradient with multiple channels across large floodplains, adapted to transmitting episodic and slow-moving flood pulses with flows diminishing downstream due to high transmission losses. At a coarse-scale, it is known that these losses sustain the biologically rich and diverse floodplain-waterhole “boom-and-bust” ecosystems, yet a detailed understanding of the way these losses are partitioned and other fundamental questions of (eco)hydrological function of these river systems cannot be understood at a detailed scale in dryland environments. This thesis aims to develop remotely-sensed data approaches to support hydrodynamic modelling in order to improve our understanding of hydrological processes in data-sparse dryland landscapes. Four objectives, which constitute the main chapters of this thesis and which are presented as 4 peer-reviewed papers, were investigated, they are: (i) to evaluate the accuracy and effectiveness of satellite derived altimetry data for estimating flood water depths in low-gradient, multi-channel rivers in central Australia; (ii) to detect and map flood extents and optimise the trade-off between image frequency and spatial resolution using Landsat and MODIS imagery; (iii) to determine the optimum Digital Elevation Models (DEMs) for hydrodynamic modelling in low gradient dryland environments in relation to accuracy, DEM preparation and trade-offs in model grid size; and (iv) to use a hydrodynamic model supported by altimetry, optical and optimal DEM data to investigate the partitioning of transmission loss within a multi-channel river in central Australia. Regarding objective (i), based on an assessment of six altimetry satellites at two lakes (in Victoria and Western Australia) and six sites along the Diamantina River and Cooper Creek, ICESat (mean = 0.00m, RMSE = 0.04m) was found to have the highest accuracy, while Jason-2 (mean = -0.04m, RMSE = 0.28m) offered potential for ongoing applications where water elevation time series are of use. Regarding objective (ii), two advanced blending algorithms were applied to MODIS and Landsat imagery; STARFM (Spatial and Temporal Adaptive Reflectance Fusion Model) and ESTARFM (Enhanced STARFM) and evaluated for nine common indices used in vegetation studies, environmental moisture assessment and standing water identification across three sites with different flood extents and spatio-temporal variability. The investigation of these factors, including the order that index calculation and blending should occur (i.e. (i) ‘Index-then-Blend’ (IB); and (ii) ‘Blend-then-Index’ (BI)), found that the IB approach was more accurate for both blending algorithms as it was; computationally less intensive due to blending single indices rather than multiple bands; more accurate due to reduced error propagation; and less sensitive to the choice of algorithm. Near-global coverage Digital Elevation Models (DEMs) such as Shuttle Radar Topography Mission (SRTM) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) are required for hydrological–hydrodynamic modelling in remote areas. For objective (iii), point accuracy and geometric co-registration error; effects of DEM preparation (vegetation smoothed and hydrologically corrected); and effects of grid size on hydrodynamic model performance were investigated. SRTM outperformed ASTER after applying geometric correction followed by vegetation smoothing and hydrological correction and a grid size of around 120m offered the optimal balance between hydrodynamic model and computational performance. Combining modelling, remotely-sensed data and limited field measurements for objective (iv), a calibrated hydrodynamic model (TUFLOW) was used to investigate the overall water balance , with a focus on transmission losses, across seven flood pulses along a 180 km reach of the Diamantina River. Results showed that transmission losses were up to 68% (mean = 46%) of the total inflow to the system, with evaporation the most significant component (21.6%), then infiltration (13.2%) and terminal water storage (11.2%). This research concluded that it is now possible to realistically constrain water balances in data-sparse dryland rivers using hydrodynamic models in combination with remote sensing and simple field measurements to address limitations in the availability of conventional hydrological datasets. This research has implications for the opportunities, limitations, and future directions of using remotely-sensed data to better understand water balance and hydrodynamics of data-sparse regions. This knowledge is imperative for improved management of the limited water resources in dryland, low-gradient, and multi-channel river systems both in Australia and around the world.

The July 4–12, 2024 eruption of Stromboli volcano produced significant effusive activity, pyroclastic density currents and a paroxysmal explosion on July 11, resulting in rapid and substantial morphological changes along the Sciara del Fuoco slope and the summit crater terrace. In this work, we present a quantitative assessment of erupted volumes and associated geomorphological modifications derived from multi-temporal Unmanned Aircraft System (UAS) surveys acquired before, during and after the eruptive sequence.High-resolution Digital Surface Models (DSMs) and co-registered visible and thermal infrared (TIR) orthomosaics, collected between October 2022 and July 2024, were analysed to reconstruct the evolution of lava flows, erosional features and collapse structures. The integration of TIR data proved essential for identifying active eruptive vents and discriminating cooling lava flows from the complex background of the Sciara del Fuoco. Lava volumes were estimated through a combination of DSM differencing and cross-sectional analyses along the main lava channel, integrating pre-eruptive (May 2024), syn-eruptive (11 July 2024) and post-eruptive (18 July 2024) datasets. TIR surveys provided the thermal constraints necessary to isolate distinct contributions from multiple eruptive vents were quantified, allowing a precise separation of early short-lived lava flows from sustained effusive activity preceding and following the paroxysmal explosion.Results indicate a total subaerial lava volume of approximately 1.3 × 10⁶ m³ (±20%), with the largest contribution associated with lava emitted from vents located within the central channel. A substantial fraction of this volume formed a lava delta at the coastline, implying the presence of an equivalent or larger submerged deposit. DSM comparisons and thermal anomalies also reveal major erosional processes, including the re-excavation of a pre-existing canyon with an estimated material removal of up to ~5 × 10⁶ m³, and a summit area collapse producing a depression of 70–90 m and a missing volume of ~1.9 × 10⁶ m³.These results highlight the effectiveness of rapid multi-sensor UAS-based surveying for near-real-time volume estimation and morphodynamic analysis during volcanic crises. This approach provides key constraints for mass balance assessments, hazard evaluation and coastal instability monitoring at active volcanoes such as Stromboli.

A small glacier of cirque-valley type existed during the Late Pleistocene Wurm Glacial in the Tudorevo and Mirovo karst valleys of Northern Velebit. Its source was in Tudorevo, and it moved through Dundovic Mirovo and Bilensko Mirovo to Baricevic Dolac, shaping U-valleys around 4 km in length. After melting, glacial deposits remained, composed of chaotic and unsorted till, composed of carbonate sand, debris and sub-rounded clasts, cobbles and blocks of predominantly Middle Jurassic and subordinately Lower Jurassic carbonate rocks. In Dundovic Mirovo and Bilensko Mirovo, where the largest masses of glacial deposits occur, terminal and recessional moraines can be found over the ground moraine, as well as some other features, mostly drumlins (drumlin field), eskers, erratic blocks, kettle holes and striations. Some erratics have been transported for more than 4 km from their primary outcrops, e.g. clasts of Lower Jurassic Toarcian Spotty limestone. A terminal moraine was deposited between Bilensko Mirovo and Baricevic Dolac, perpendicular to the glaciated U-valley and it forms the Bilo hill, the northern and southern foothills of which are composed partly of glaciofluvial deposits. Between Tudorevo and Mirovo, a recessional moraine occurs above the ground moraine. The glacier was subject to polyphase melting and freezing, and the youngest freezing events may be related to cirques in Tudorevo. During melting events, glacier lakes are supposed to have existed, initially in the Baricevic Dolac, later in Mirovo area and finally in Tudorevo. These discharged into the karst underground by percolation through till and by erosion to the karstified underlying Middle Jurassic carbonates.

Late Wisconsinan end moraines on Cape Cod and islands south and west of Cape Cod are believed to be glaciotectonic features formed by advancing ice fronts. Evidence of a glaciotectonic origin includes the stratified drift composition of the moraines, dislocated preglacial and glaciolacustrine deposits, tilted preglacial and glacial beds, folding and thrust faulting, and morphologic similarity to ancient and modern glaciotectonic moraines. Evidence for major ice readvances during over-all general recession includes the moraines themselves, till atop stratified drift, and the numerous basal tills that are inferred to exist beneath Cape Cod Bay. The Thompson Glacier end moraine in the Canadian Arctic Archipelago is considered to be a modern example of how late Wisconsinan end moraines on Cape Cod and the islands were formed. The Thompson Glacier is overriding its outwash plain, displacing outwash deposits forward and upward beyond the ice front. New sheets are added to the base of the moraine, and till is deposited atop the moraine as the ice overrides it. Evidence from Cape Cod and the nearby islands indicates that over-all recession of late Wisconsinan ice was characterized by alternating episodes of ice-front retreat, during which the outwash plains were formed, and of ice-front advance, during which the moraines were built. Retreat of the ice from Cape Cod and the islands may have been similar to the retreat of the Lake Michigan lobe, deposits of which contain evidence of at least 12 moraine-building episodes caused by readvancing ice during the over-all retreat of the late Wisconsinan ice sheet.

IntroductionThe Northeast black soil area is an important marketable grain base in China. However, due to soil erosion, the black soil layer has been gradually thinning and its quality deteriorating. Therefore, accurately assessing the extent of soil erosion in this region is essential for the protection and sustainable utilization of black soil resources.MethodsIn this study, linear and nonlinear models were compared combined with remote sensing images to invert soil organic carbon (SOC). In the scenario of SOC change, temporally variable soil erodibility factor were obtained. Then based on the RUSLE model and GIS technology, land use, rainfall, soil texture and digital elevation model (DEM) were used to evaluate the temporal and spatial variation characteristics of soil erosion in black soil region from 1995 to 2020 in Hulan River Basin. The main influencing factors were explored by random forest model and analyzes in combination with eco-geological.ResultsThe findings are as follows: The random forest (RF) model was optimal for SOC inversion (2020: R2 = 0.64, RMSE = 0.70, 2010: R2 = 0.66, RMSE = 0.35). The erosion intensity was mainly slight or mild while mean annual soil loss firstly decreased then increased from 1995 to 2020 reaching a rate of 1020.16 t km−2 y−1 by 2020. Rainfall and topography were the main driving factors of soil conservation changes, and soil erosion was more likely to occur in the eco-geological environment of the neutral rock hilly woodland area.DiscussionThe results provide insights into spatial distribution characteristics of black soils erosion which are crucial for preventing further degradation and ensuring national food security.

The Pleistocene end moraine fans: controls on their sedimentation and location

Whale bones overlain by moraine at Borgoy island have been dated to 12,380 ± 150 B.P. At Tveit, further east, whale bones overlain by littoral material were dated to 11,970 ± 100 B.P. These datings, together with the glacial striae in the area, show that Borgoy was covered by ice during a glacial advance at about Older Dryas Chronozone, while Tveit was not, and that a calving bay existed in the inner part of the Boknfjord area at the same time. At the mouth of Vindafjord, east of Tveit, and 3-4 km outside terminal moraines of Younger Dryas age, shells overlain by ground moraine were dated to 11,630 ± 100 B.P. This shows that the ice front in an early phase of the Younger Dryas glacial advance was situated at least 3–4 km beyond the pronounced Ra moraines in Vindafjord. The main trend of the shore line displacement between 12,000 and 9,500 B.P., based upon the whale bones and earlier investigations, can be established.

Warm water masses circulating at depth off the coast of Greenland play an important role in controlling rates of mass loss from the Greenland Ice Sheet through feedbacks associated with the melting of marine glacier termini. The ability of these warm waters to reach glacier termini is strongly controlled by fjord bathymetry, which was unmapped for the majority of Greenland’s fjords until recently. In response to the need for bathymetric measurements in previously uncharted areas, we developed two companion methods to infer fjord bathymetry using icebergs as depth sounders. The main premise of our methods centers around the idea that deep-drafted icebergs will become stranded in shallow water such that estimates of iceberg surface elevation can be used to infer draft, and thus water depth, under the assumption of hydrostatic equilibrium. When and where available, surface elevations of icebergs stranded on bathymetric highs were extracted from digital elevation models (DEMs) and converted to estimates of iceberg draft. To expand the spatial coverage of our inferred water depths beyond the DEM footprints, we used the DEMs to construct characteristic depth–width ratios and then inferred depths from satellite imagery-derived iceberg widths. We tested and applied the methods in two fjord systems in western Greenland with partially constrained bathymetry, Ilulissat Isfjord and Naajarsuit Fjord, to demonstrate their utility for inferring bathymetry using remote sensing datasets. Our results show that while the uncertainties associated with the methods are high (up to ±93 m), they provide critical first-order constraints on fjord bathymetry.