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Aiming to support disaster recovery, we have developed a new method to extract damaged buildings by using machine learning that combines 10 explanatory variables obtained from analysis of aerial photographs and observation data. We used site amplification factors, seismic intensities of foreshock and mainshock, distance from faults, estimated building structures and ages, coverage by blue tarps, texture analysis, and digital surface model differences before and after the earthquake as explanatory variables, in addition to convolutional neural network prediction results based on post-earthquake aerial photographs. The random forest method resulted in an overall accuracy of about 81% and an average F-measure of three classes was about 70%, indicating that it can classify possible damage to buildings more accurately than our previous studies. [ABSTRACT FROM AUTHOR]

Williams, H.F.L., 2024. Testing digital elevation model of difference (DoD) estimation of washover fan thickness, Matagorda Peninsula, Texas. Journal of Coastal Research, 40(5), 852–859. Charlotte (North Carolina), ISSN 0749-0208. Washover fans are a fundamental component of coastal sediment budgets. While fans can be relatively easily delineated on air photos to obtain fan area, measurement of fan thickness, which is required for volume estimation, is problematic. Field surveys can be conducted, but fieldwork can be labor-intensive, costly, and time-consuming and have access problems. This study used pre- and poststorm LIDAR digital elevation models (DEMs) to create a digital elevation model of difference (DoD), which was then used to estimate the mean thicknesses of 10 Hurricane Harvey washover fans on Matagorda Peninsula, Texas. The accuracy of the LIDAR-derived fan thicknesses was assessed by comparing the LIDAR results to fan mean thicknesses based on pits excavated into fans. Seven out of 10 LIDAR-based thicknesses underestimated pit-based thicknesses, suggesting the presence of systematic bias in the LIDAR-derived DEMs. Underestimation of fan thicknesses was in the range of 36% to 56%. The source of the suspected bias is uncertain; it is possible that compaction of marsh sediments by the washover fans lowered the fans and reduced their apparent thicknesses. It is concluded that pre- and post-storm LIDAR DEMs can be used to estimate washover fan thickness, but in areas of compactible substrates, such as coastal marshes, steps should be taken to identify, evaluate, and address potential bias in the DEM data. [ABSTRACT FROM AUTHOR]

The Bale Mountains National Park (BMNP) in Ethiopia comprises the largest fraction of the Afro-Alpine ecosystem in Africa, which provides vital mountain ecosystem services at local, regional, and global levels. However, the BMNP has been severely threatened by natural and anthropogenic disturbances in recent decades. In particular, landscape alteration due to human activities such as red ash quarrying has become a common practice in the BMNP, which poses a major environmental challenge by severely degrading the Afro-Alpine ecosystem. This study aims to quantify the long-term volumetric changes of two red ash quarry sites in the BMNP using historical aerial photographs and in situ data, and to assess their impact on the Afro-Alpine ecosystem. The Structure-from-Motion multi-view stereo photogrammetry algorithm was used to reconstruct the three-dimensional landscape for the year 1967 and 1984 while spatial interpolation techniques were applied to generate the current digital elevation models for 2023. To quantify the volumetric changes and landscape alteration of the quarry sites, differences in digital elevation models were computed. The result showed that the volume of resources extracted from the BMNP quarry sites increased significantly over the study period from 1984 to 2023 compared with the period from 1967 to 1984. In general, between 1967 and 2023, the total net surface volume of the quarry sites decreased by 503,721 ± 27,970 m3 and 368,523 ± 30,003 m3, respectively. The extent of the excavated area increased by 53,147 m2 and 45,297 m2 for Site 1 and 2, respectively. In terms of habitat loss, major gravel road construction inside the BMNP resulted in the reduction of Afro-Alpine vegetation by 476,860 m2, ericaceous vegetation by 403,806 m2 and Afromontane forest by 493,222 m2 with associated decline in species diversity and density. The excavation and gravel road construction have contributed to the degradation of the Afro-Alpine ecosystem, especially the endemic Lobelia rhynchopetalum on the quarry sites and roads. If excavation continues at the same rate as in the last half century, it can threaten the whole mountain ecosystem of the National Park and beyond, highlighting the importance of preventing these anthropogenic changes and conserving the remaining Afro-Alpine ecosystem. [ABSTRACT FROM AUTHOR]

Contextualization: Direct measurement of biomass in pastures is the most reliable method; however, it is a destructive and wasteful method. Knowledge gap: Recently, techniques using remote sensing to estimate physiological and morphological characteristics in crops have been investigated from their optical properties and reach biomass estimates. It is valuable to evaluate these techniques in perennial forages such as Kikuyu grass (Cenchrus clandestinus). Purpose: This work aimed to develop a methodology to estimate biomass in prairies based on their spectral and morphological characteristics using different sources of remote information. Methodology: A grazing strip of 1870 m² was used, subdivided into 27 subplots, where direct measurements of biomass and undisturbed height (ASD, for its Spanish acronym) were carried out. Aerial photographs were taken with a UAS. A Sentinel 2B satellite image that captured the scene of the study site coinciding with the UAS flight date and the field measurements was selected. A digital elevation model (DEM) was calculated using aerial photogrammetry techniques, which was used to estimate pasture height. The Red-Green-Blue Vegetation Index (RGBVI) was calculated from the orthophotography, and the Normalized Difference Vegetation Index (NDVI) was determined from the satellite image. The height measured in the field was correlated with the estimated height by DEM using the Pearson correlation coefficient. The biomass measured in the field was correlated with the NDVI, RGBVI, and the estimated height through linear regression models. Results and conclusions: A strong correlation (0.64) was found between the directly measured height and the height calculated using the DEM. However, the correlation between NDVI and biomass was low (R2= 0.13), and no relationship was found with the RGBVI index (R2= 0.02). An average relationship (R2=0.42) was found between the height estimated by DEM and the biomass, indicating that this is a promising methodology to replace destructive methods and to provide more accurate information in time and space. [ABSTRACT FROM AUTHOR]

The natural resources of Ethiopian high-altitude ecosystems are commonly perceived as increasingly threatened by devastating land-use practices owing to decreasing lowland resources. Quantified time-series data of the course of land-use cover changes are still needed. Very-high-resolution digital data on the historical landscape over recent decades are needed to determine the impacts of changes in afro-alpine ecosystems. However, digital elevation models (DEMs) and orthomosaics do not exist for most afro-alpine ecosystems of Africa. We processed the only available and oldest historical aerial photographs for Ethiopia and any afro-alpine ecosystem. Here, we provide a DEM and an orthomosaic image for the years 1967 and 1984 for the Bale Mountains in Ethiopia, which comprise the largest afro-alpine ecosystem in Africa. We used 298 historical aerial photographs captured in 1967 and 1984 for generating DEMs and orthomosaics with a structure-from-motion multi-view stereo photogrammetry workflow along an elevation gradient from 977 to 4377 m above sea level (a.s.l.) at very high spatial resolutions of 0.84 m and 0.98 m for the years 1967 and 1984, respectively. The structure-from-motion multi-view stereo photogrammetry workflow, employed with Agisoft Metashape, represents a modern approach that combines computer vision and photogrammetry. This method proves useful for reconstructing DEMs and orthomosaics from historical aerial photographs, with a focus on high spatial resolution. To validate the accuracy of the reconstructed DEMs, ground control points gathered through GPS measurements were used, resulting in root mean square error (RMSE) values of 3.55 m for the year 1967 and 3.44 m for the year 1984. Our datasets can be used by researchers and policymakers for watershed management, as the area provides water for more than 30 million people, landscape management, detailed mapping, and analysis of geological and archaeological features as well as natural resources, analyses of geomorphological processes, and biodiversity research. All the datasets are available online at 10.5281/zenodo.7271617 (Muhammed et al., 2022a) for all the inputs used and at 10.5281/zenodo.7269999 (Muhammed et al., 2022b) for the results obtained (very-high-resolution DEMs and orthomosaics) for both the years 1967 and 1984. [ABSTRACT FROM AUTHOR]

The Fagradalsfjall eruption commenced on 19 March 2021 on a ~180-m-long eruptive fissure, following a 23-day dike intrusion. New eruptive fissures opened northeast of the initial eruption site on 5, 6–7, 10, and 13 April 2021. The northernmost eruption occurred on 5 April, approximately 1 km northeast of the initial fissure, with the other fissure openings between this and the initial eruptive vents. Still images from web cameras and time-lapse cameras are available for five of the fissure openings. These data show that the eruptions were preceded by steam emitted from cracks in the exact locations where the eruptions started. The time between the first steam observations and the visual appearance of glowing lava ranged between 15 s and 1.5 min during night observations and from 9 to 23 min during daytime observations. The difference in observation time is likely explained by the different lighting conditions. The eruptive vents are located where the north-easterly oriented dike intersected pre-existing north-south-oriented fractures, inferred to be strike-slip faults. These fractures could be identified on a high-resolution ICEYE interferogram as well as on pre-existing aerial photographs and digital elevation models. This interferogram spanned the first day of the eruption (19–20 March 2021). It not only displays deformation related to the pre-eruptive dike intrusion but also shows lineations in locations where eruptive vent openings occurred later in April 2021. These findings demonstrate how Interferometric Synthetic Aperture Radar Analysis (InSAR) can be used to forecast likely locations of subsequent eruptive vent openings, which is of great importance for hazard assessment and defining exclusion zones during fissure eruptions. [ABSTRACT FROM AUTHOR]

The South Col Glacier is a small body of ice and snow (approx. 0.2 km 2) located at the very high elevation of 8000 m a.s.l. (above sea level) on the southern ridge of Mt. Everest. A recent study by proposed that South Col Glacier is rapidly losing mass. This is in contradiction to our comparison of two digital elevation models derived from aerial photographs taken in December 1984 and a stereo Pléiades satellite acquisition from March 2017, from which we estimate a mean elevation change of 0.01 ± 0.05 m a -1. To reconcile these results, we investigate some aspects of the surface energy and mass balance of South Col Glacier. From satellite images and a simple model of snow compaction and erosion, we show that wind erosion has a major impact on the surface mass balance due to the strong seasonality in precipitation and wind and that it cannot be neglected. Additionally, we show that the melt amount predicted by a surface energy and mass balance model is very sensitive to the model structure and implementation. Contrary to previous findings, melt is likely not a dominant ablation process on this glacier, which remains mostly snow-covered during the monsoon. [ABSTRACT FROM AUTHOR]

We propose an optimized Structure-from-Motion (SfM) Multi-View Stereopsis (MVS) workflow, based on minimizing different errors and inaccuracies of historical aerial photograph series (1945, 1979, 1984, and 2008 surveys), prior to generation of elevation-calibrated historical Digital Surface Models (hDSM) at 1 m resolution. We applied LiDAR techniques on Airborne Laser Scanning (ALS) point clouds (Spanish PNOA LiDAR flights of 2014 and 2019) for comparison and validation purposes. Implementation of these products in multi-temporal analysis requires quality control due to the diversity of sources and technologies involved. To accomplish this, (i) we used the Mean Absolute Error (MAE) between GNSS-Validation Points and the elevations observed by DSM-ALS to evaluate the elevation accuracy of DSM-ALS generated with the LAScatalog processing engine; (ii) optimization of the SfM sparse clouds in the georeferencing step was evaluated by calculating the Root Mean Square Error (RMSE) between the Check Points extracted from DSM-ALS and the predicted elevations per sparse cloud; (iii) the MVS clouds were evaluated by calculating the MAE between ALS-Validation Points and the predicted elevations per MVS cloud; iv) the accuracy of the resulting historical SfM-MVS DSMs were assessed using the MAE between ALS-Validation Points and the observed elevations per historical DSM; and (v) we implemented a calibration method based on a linear correction to reduce the elevation discrepancies between historical DSMs and the DSM-ALS 2019 reference elevations. This optimized workflow can generate high-resolution (1 m pixel size) hDSMs with reasonable accuracy: MAE in z ranges from 0.41 m (2008 DSM) to 5.21 m (1945 DSM). Overall, hDSMs generated using historical images have great potential for geo-environmental processes monitoring in different ecosystems and, in some cases (i.e., sufficient image overlapping and quality), being an acceptable replacement for LiDAR data when it is not available. [ABSTRACT FROM AUTHOR]

The Jostedalsbreen ice cap is mainland Europe's largest ice cap and accommodates 20% (458 km2 in 2019) of the total glacier area of mainland Norway. Jostedalsbreen and its meltwater contribute to global sea-level rise and to local water management, hydropower and tourism economies and livelihoods. In this study, we construct a digital terrain model (DTM) of the ice cap from 1966 aerial photographs, which by comparing to an airborne LiDAR DTM from 2020, we compute changes in surface elevation and geodetic mass balances. The area mapped in both surveys cover about 3/4 of the ice cap area and 49 of 82 glaciers. The measured glacier area has decreased from 363.4 km2 in 1966 to 332.9 km2 in 2019, i.e. a change of −30 km2 or −8.4% (−0.16% a−1), which is in line with the percentage reduction in area for Jostedalsbreen as a whole. The mean geodetic mass balance over the 49 glaciers was −0.15 ± 0.01 m w.e. a−1, however, large variability is evident between glaciers, e.g. Nigardsbreen (−0.05 m w.e. a−1), Austdalsbreen (−0.28 m w.e. a−1) and Tunsbergdalsbreen (−0.36 m w.e. a−1) confirming differences also found by the glaciological records for Nigardsbreen and Austdalsbreen. [ABSTRACT FROM AUTHOR]

During the last 3 ka, different human communities occupied the Bay of Cádiz (SW Spain), including Phoenician, Carthaginian, Roman, Medieval and Modern settlements. Traces of such historical occupations have been recognized along the bay from a geoarchaeological point of view. Some of them bear a palaeogeographical interest related to the historical location of the shoreline. At the same time, Holocene sedimentary units and geomorphological elements identified along the bay can be interpreted as evidences of its morphological evolution. The objective of the present paper is to represent all the available data about archaeological sites and geomorphology in the northern Bay of Cádiz, with the aim of combining both sources of data for elaborating a simple proposal of landscape evolution during the last 3 millennia. The base for mapping was multiple, from historical aerial photographs to satellite imagery and a digital terrain model with a maximum resolution of 0.35 m. [ABSTRACT FROM AUTHOR]

Accurate digital elevation models represent the basic tool for a large spectrum of applications, including geological, architectonic, archaeological, and urbanistic studies. However, aggressive urbanization may significantly alter the morphology of areas of interest. Such is the case of the active Campi Flegrei caldera in southern Italy, where all the buildings, facilities, infrastructures, quarries, and landfills altered the original volcanic morphology. To avoid these limitations, we analyzed a set of vintage aerial photographs acquired in 1943 by Italy's Military Geographic Institute (IGM). We reconstructed the study area's topography before the deep anthropic modification from the 1960s onwards by applying Structure-from-Motion photogrammetric processing. On the reconstructed orthomosaic and a historical-Digital Surface Model (hDMS), we conducted geomorphic analyses along 18 longitudinal stream profiles outside, across the border, and inside the caldera, underlining that the rectilinear sections with preferred orientations and increased incision values suggest a strong structural underpinning on valley incision and stream paths. The analysis of the spatial distribution of sinuosity, SL index, Chi (χ) value and knickpoint maps suggests the presence of tectonic lineaments that influence the stream network from the pre-caldera (>40 ka) to recent times, producing articulated caldera and craters geometry as well as affecting the localization of volcanic vents. The comparison between the 1943 hDSM and 2013 LiDAR (Light Detection and Ranging) DSM allowed us to spotlight the areas that show the most significant differences due to anthropic intervention that obliterated critical features, thus supporting our motivation to use this base. Overall, the results indicate that long-lived volcano-tectonic and tectonic structures control the orientation of drainage patterns and their re-arrangements during volcano-tectonic deformation phases. Finally, a comprehensive structural map, based on the merged 1943 hDSM and the bathymetric DEM, is presented together with a conceptual evolutionary model of the stream network across the caldera border. Under the proper acquisition conditions, vintage aerial photographs can provide a useful tool for morphological analysis and can be applied to several topics in the geosciences. • The original topography of Campi Flegrei is restored using historical aerial photographs. • Several geomorphic indices highlight the activity of volcano-tectonic structures. • Rectilinear and deeply incised valleys occur in different sectors. • NE–SW and NW–SE oriented tectonic features are overprinted by E–W oriented features. • Tectonic lineaments control the occurrence of volcanism through time. [ABSTRACT FROM AUTHOR]

Earthquake surface deformation provides key constraints on the geometry, kinematics, and displacements of fault rupture. However, deriving these characteristics from past earthquakes is complicated by insufficient knowledge of the pre‐event landscape and its post‐event modification. The 1987 Mw 6.5 Edgecumbe earthquake in the northern Taupō volcanic zone (TVZ) in New Zealand represents a moderate‐magnitude earthquake with distributed surface rupture that occurred before widespread high‐resolution topographic data were available. We use historical aerial photos to build pre‐ and post‐earthquake digital surface models (DSMs) using structure‐from‐motion techniques. We measured discrete and distributed deformation from differenced DSMs and compared the effectiveness of the technique to traditional field‐ and lidar‐based studies. We identified most fault traces recognized by 1987 field mapping, mapped newly identified traces, and made dense remote slip measurements with a vertical separation resolution of ∼0.3 m. Our maximum and average vertical separation measurements on the Edgecumbe fault trace (2.5 ± 0.3 and 1.2 m, respectively), are similar to field‐based values of 2.4 and 1.1 m, respectively. Importantly, this technique can discern between new and pre‐existing fault scarps better than field techniques or post‐earthquake lidar‐based measurements alone. Our surface displacement results are used to refine subsurface fault geometries and slip distributions at depth, which are further used to investigate potential magmatic‐tectonic stress interactions in the northern TVZ. Our results suggest the Edgecumbe fault dips more gently at depth than at the surface, hosted shallow slip in 1987, and may be advanced toward failure by interactions with nearby magma bodies. Plain Language Summary: Understanding earthquake behavior relies heavily on information about how past earthquakes changed the landscape. Detailed information about the surface topography before the earthquake is often limited, creating challenges for accurately measuring earthquake surface deformation. Aerial photos are widely available and can be used to create 3D digital surface models in places where other topographic information is lacking. We use historical aerial photos to make 3D datasets of the surface topography before and after the 1987 Edgecumbe earthquake in New Zealand. We calculated the difference between the two 3D datasets to identify and measure how the earthquake changed the landscape, and compared our results to previous measurements. We found that this method generally works as well as field methods for identifying and measuring fault movement, and has some advantages over other techniques. In particular, this approach can separate deformation from individual earthquakes, which had previously been a challenge. The results refine our understanding of the faults below the surface, provide insight into the earthquake's relationship to surrounding faults and volcanic systems, and allow us to better characterize seismic hazard both here and in other similar geologic settings. Key Points: Historical aerial photos can be used to generate pre‐ and post‐earthquake digital surface models for measuring displacementThis method performs at least as well as field surveys, and better captures single‐event displacements to constrain earthquake behaviorThe Edgecumbe earthquake is important for understanding low dip‐angle normal fault ruptures and possibly magma‐tectonic interactions [ABSTRACT FROM AUTHOR]

The retreat of the last Irish Ice Sheet across the Irish midlands resulted in the formation of an ice‐contact lake, Palaeolake Riada, along its eastern margin during recession. However, the full extent and characteristics of the lake and its impact on ice dynamics are unknown, as glacigenic landforms and deposits relating to the lake have not been mapped in sufficient detail to allow reconstruction of ice‐marginal behaviour. This paper presents new mapping of subglacial, ice‐marginal and glaciolacustrine landforms and deposits in the Irish midlands. Glacial landforms and landform associations across this wide area have been identified using aerial photographs and high‐resolution digital elevation models derived from LiDAR and radar data. Reconstructions of successive ice‐margin retreat positions are combined with glacio‐isostatically adjusted digital elevation models to identify the probable position of lake outflows and reconstruct the development of the proglacial Palaeolake Riada through time. These reconstructions indicate that at its largest, Palaeolake Riada had an ice‐contact margin of 113 km, and covered an area of over 2300 km2. Initially, ice recession was concentrated around meltwater discharge outlets, but these became less important as the lake expanded and thermo‐mechanical erosion occurred along the entire subaqueous margin. [ABSTRACT FROM AUTHOR]

Geographic information systems (GIS) are an effective tool for storing, managing and displaying spatial data. The application of GIS in water resources management is constantly increasing. In this regard, the purpose of this article is to study the morphological anthropogenic changes occurring in the surface water body BG2PR210R1005 (Devnya River after the village of Chernevo to the inflow in Provadiyska River). For this purpose, GIS was created, which includes aerial photographs (taken in 1942 and 1957), analog topographic maps 1: 5000 (1966 and 1987) and orthophoto maps (2006, 2011 and 2014), digital elevation model (DEM). As a result of the performed spatial analysis of the indicated sources, the anthropogenic factors and the morphological changes caused by them on the Devnya River after the village of Chernevo have been determined. In the course of the research it was proved that the river Hamam Dere (considered to be the beginning of the river Devnya) has no connection with the river Devnya. In addition, the Hamam Dere River is defined as a Heavily Modified Surface Water Body (HMSWB) only within the boundaries of a spring (Myziiska cheshma) to the Kairyaka area. The obtained results are important for the responsible institutions (Basin Directorate of the Black Sea Water Management Region) and the public. [ABSTRACT FROM AUTHOR]

Efficient methods for shallow water data collection have been employed to create comprehensive bathymetric surfaces for 3 Georgia sounds. Survey areas were characterized using existing charted depths, aerial photographs, and lidar-derived elevation data to identify regions shallower than 3-m mean lower low water. Single-beam sonar missions were completed for these shallow areas using various marine platforms to constrain the existing 3-m isobath. Below 3 m, waters are deep enough, and swath width is wide enough, to use a larger vessel with an interferometric sonar system collecting swath bathymetry and sidescan imagery. The collected data were merged and gridded in a geographic information system environment to generate digital elevation models. The modern digital surfaces were compared with historic depth data to identify areas of shoaling and deepening. The mean overall change between the historic data and modern data was relatively small (0.7 m for Wassaw Sound, 0.4 m for Ossabaw Sound, and 0.1 m for Sapelo Sound); only the change in Wassaw was greater than the error in the analysis. However, each sound exhibited up to 20 m of shoaling and deepening associated with entrance channel migration, illustrating that a significant change occurs in specific geomorphic zones in each of these settings. Sediment grabs ground-truth sidescan sonar imagery to interpret environmental energy and bottom character. The mean sediment size for all sounds fell in the fine to very fine sand range (2–4 phi), reflecting the characteristics of the coastal sediment prism, although gravels and muds characterize areas of scour and quiescent conditions, respectively. These surveys led to the first identification of hard-bottom habitats of erosion-resistant, vertical cliffs up to 10 m high and 1000 m long in Southeastern US estuaries. [ABSTRACT FROM AUTHOR]

We used a low-cost hobby drone to produce high resolution aerial photographs of a 12 ha mature longleaf pine (Pinus palustris) stand. The photos were combined into orthophoto mosaics and digital surface models to produce repeatable crown maps. Repeated flights allowed the use of tree phenology to separate longleaf from loblolly (Pinus taeda) and pond (Pinus serotina) pines, as well as some hardwood species. Careful ground control was necessary to produce aerial crown maps that matched field measured stems. However, average crown area/stem basal area ratio of 15 m radius plots produced correlation coefficients comparable to open single tree measures, ground control improved the relationship especially for loblolly and pond pine. With ground control height measurement was comparable to SfM (Surface from Motion) research results but had a positive bias greater than 1m. The most difficult problem was determining individual trees associated with a mapped crown area. Height measures were hampered by our inability to determine a correction for the true ellipsoid height of the camera. [ABSTRACT FROM AUTHOR]

Generating precise and up-to-date landslide susceptibility maps (LSMs) in landslide-prone areas is important to identify hazard potential in the future. The data quality and the method selection affect the accuracy of the LSMs. In this context, the accuracy and precision of the digital elevation models (DEMs) used as input are among the most important performance elements. Therefore, the influence of DEM accuracy and spatial resolution in producing LSMs was investigated here. A high accuracy DEM with 5 m grid spacing produced from aerial photographs and the EU-DEM v1.1 freely accessible from Copernicus Land Monitoring Service with 25 m spatial resolution were used for producing two different LSMs using the Random Forest (RF) method in this study. The RF method has proven success for this purpose. A total of eight conditioning factors, which include topographical and geological features, was used as model input. The landslide inventory was derived with the help of aerial stereo images with 20 cm and 30 cm ground sampling distances. The performances of the LSMs were assessed with receiver operating characteristics (ROC) area under curve (AUC) values. In addition, the results were compared with visual inspection. The results show that although the AUC values obtained from the aerial DEM (0.95) and EU-DEM v1.1 (0.93) were comparable; based on the visual assessments, the LSM obtained from the higher resolution DEM was found more successful in detecting the landslides and thus exhibited better prediction performance. [ABSTRACT FROM AUTHOR]

In January 1980, during exceptional cyclonic rainfall, an atypical landslide, called déboulé, rapidly generated the permanent 700 m-long gully of the Ravine de l'Eglise on an inhabited plateau in Reunion Island (Indian Ocean). Retrieving the initial conditions that led to this historical process is both challenging and necessary for understanding the mechanism of gully incision and providing pointers for improving risk mitigation in relation to this phenomenon. In this study, we reconstruct the pre- and post-failure topographies using SFM (structure from motion) applied on archive aerial photographs. Based on the comparison of these digital elevation models, we estimate the volume of material eroded to be ca. 0.63 Mm3. Groundwater level increase, part of the triggering mechanism, is hindcast in the catchment of the gully using a lumped hydrological model. This model shows that in only a fortnight the groundwater level probably rose by 36 m, which could have caused a progressive increase in pore pressure and triggered formation of the gully by retrogressive landslides. We test this hypothesis by considering the pre-failure topography and the hindcast groundwater level in a deterministic model based on limit equilibrium equations to explore ground stability. The evolution of ground stability with a rise in the water table shows that the gully may have extended in a headward direction by retrogressive landslides. This is the first quantitative reconstruction of an exceptional historical event affecting the territory of Reunion Island. The methods used to investigate the Ravine de L'Eglise incision thus offer new complementary insights and challenges for understanding the mechanism and the temporality of gully formation. [ABSTRACT FROM AUTHOR]

Archival spatial data sources (maps and aerial photographs) allow reconstruction and 3D visualization of landscapes that have been altered by human activity. This article is dedicated to the reconstruction of the 300 km‐long pre‐dam valley of the Vltava River (Czech Republic, Europe) inundated by nine reservoirs built between 1930 and 1992. We used methods based on archival aerial photographs and old maps to reconstruct pre‐dam georelief, which is exceptional because the total area subject to the reconstruction is 1,670 km2. We found that old maps are preferred for terrain reconstruction. The map series "State Map Derived 1:5,000" released between 1950 and 1959 was chosen as the most suitable data source for the pre‐dam valley reconstruction because this map series covers the entire area of interest with elevation information. Based on the processed maps, more than 26,000 km of contour lines were derived by semi‐automatic vectorization. The resulting pre‐dam digital elevation model (DEM) was created using a combination of interpolation techniques. We demonstrated that the methods used for georelief reconstruction under standard conditions should be used carefully while working with such large areas. Geostatistical analysis was performed to verify the accuracy of the resulting DEM. The differences between the model and LiDAR surveyed data were analyzed from three points of view: spatial autocorrelation, normality, and elevation stability. We tested several 3D printing methods for producing a realistic 3D model with a texture applied. The computer numerical control (CNC) milling method was chosen to produce 3D models of the three reservoirs at scales of 1:8,000 and 1:6,000. [ABSTRACT FROM AUTHOR]

This work aims to study the vertical planning method for the terrain area as part of the process of construction geodetic support. Such planning will be carried out based on the aerial survey data from UAVs, which allow the creation of a high-quality digital elevation model (DEM) with sufficient node density for reliable surface terrain modelling. During the study, we test the hypothesis of the possibility of using archival aerial photographs from UAVs to model the terrain of the local area. Both the actual achievable accuracy of terrain modeling in the course of photogrammetric processing of archived aerial photographs, and methods for creating a polygonal terrain model using input spatial data in the form of clouds of 3D points of a given density require analysis. To do this, we will perform comparisons of the accuracy of calculating earth masses, carried out based on the digital triangulation elevation models (TIN). These models were based on different algorithms for creating Delaunay triangulation with different degrees of 3D point sparsity. We proposed to use sparsity of dense clouds of points representing the surface of the terrain and which were obtained by the photogrammetric method. Computer terrain modelling and calculation of vertical planning parameters were performed by us for the area with flat terrain at angles up to 3.5 degrees. We evaluated the potential of archived UAV aerial photographs and algorithms for creating Delaunay triangulation at different densities of its nodes for calculating the volumes of earth masses. [ABSTRACT FROM AUTHOR]

In-stream mining is a common aggregate mining practice around the world. However, the impacts of such practice are not always taken into account when the mines are established, and the environmental cost of in-stream aggregate mining is generally not assessed. The purpose of this study was to evaluate the impacts of aggregate mining conducted in La Puerta River (Tafí valley, Northwest Argentina), a dry-pit instream mine, by considering the geomorphological, geoarchaeological, and human effects. Multitemporal analysis of the area using remote sensors (aerial photographs and satellite images 1970-2020), high-resolution drone digital elevation models and orthomosaics (2018-2019), and an intensive survey demonstrated that the mining area grew exponentially between 2002 and 2020 under unregulated mining. As a result, this practice exerts great environmental impact, including channel section alterations and destabilization of riverbanks, soil loss, river profile changes, and the formation of lag deposits of discarded materials, thus increasing environmental hazard under unpredictable flows. Finally, this is a highly touristic area that has suffered substantial landscape degradation and irreversible archaeological damage. [ABSTRACT FROM AUTHOR]

Traditional landscape photographs reaching back until the second half of the nineteenth century represent a valuable image source for the study of long-term landscape change. Due to the oblique perspective and the lack of geographical reference, landscape photographs are hardly used for quantitative research. In this study, oblique landscape photographs from the Norwegian landscape monitoring program are georeferenced using the WSL Monoplotting Tool with the aim of evaluating the accuracy of point and polygon features. In addition, the study shows how the resolution of the chosen digital terrain model and other factors affect accuracy. Points mapped on the landscape photograph had a mean displacement of 1.52 m from their location on a corresponding aerial photograph, while mapped areas deviated on average 5.6% in size. The resolution of the DTM, the placement of GCPs and the angle of incidence were identified as relevant factors to achieve accurate geospatial data. An example on forest expansion at the abandoned mountain farm Flysetra in Mid-Norway demonstrates how repeat photography facilitates the georectification process in the absence of reliable ground control points (GCPs) in very old photographs. [ABSTRACT FROM AUTHOR]

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The Aneto, located on the Maladeta Massif (Central Pyrenees), is the largest glacier of the Pyrenees. The glacier is 675 m long, occupies an area of 48.64 ha and has a maximum altitude of 3269 m. In this study, we present a detailed area, volume, ice thickness, and Equilibrium Line Altitude reconstruction of the glacier for different periods (LIA, 1957, 1983, 2000, 2006, 2015, and 2017) and analyze its retreat. To estimate the glacier extent during the LIA, the moraines were mapped by using photo interpretation techniques whereas for the recent stages digital satellite images and aerial photographs were used. Moreover, we estimated the topography of the glacier using a simple steady-state model that assumes a perfectly plastic ice rheology, which allowed reconstructing the theoretical ice profiles of the glacier. To reconstruct the ice surface, a digital elevation model was created and combined with the bedrock topography in order to obtain the ice thickness of each stage. The results of the study reveal a considerable retreat of the Aneto Glacier since the LIA. The length of the glacier has reduced from 1970 to 675 m from LIA to2017, and its tongue has retreated from 2385 to 3029 m a.s.l. Furthermore, the glaciated area has been reduced from 245 to 48.64 ha from LIA to 2017 and the ELA has risen from 2919 to 3139 m a.s.l. The data obtained indicates that in the LIA–2017 period the glacier volume has been reduced from 82.57 m × 106 m3 to 3.48 m × 106 m3 and the maximum ice thickness from 95 to 27m. We also reconstructed the climatic conditions, showing an increase in temperature of ~1.14°C from LIA to 2017. These data reveal a vast retreat of the glacier since the LIA, which has accelerated since the 1980's and even more since the year 2000. [ABSTRACT FROM AUTHOR]

Copyright of Mediterranean Agricultural Sciences is the property of Akdeniz Universitesi Ziraat Fakultesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents hydrometeorological, glaciological and geospatial data from the Peyto Glacier Research Basin (PGRB) in the Canadian Rockies. Peyto Glacier has been of interest to glaciological and hydrological researchers since the 1960s, when it was chosen as one of five glacier basins in Canada for the study of mass and water balance during the International Hydrological Decade (IHD, 1965–1974). Intensive studies of the glacier and observations of the glacier mass balance continued after the IHD, when the initial seasonal meteorological stations were discontinued, then restarted as continuous stations in the late 1980s. The corresponding hydrometric observations were discontinued in 1977 and restarted in 2013. Datasets presented in this paper include high-resolution, co-registered digital elevation models (DEMs) derived from original air photos and lidar surveys; hourly off-glacier meteorological data recorded from 1987 to the present; precipitation data from the nearby Bow Summit weather station; and long-term hydrological and glaciological model forcing datasets derived from bias-corrected reanalysis products. These data are crucial for studying climate change and variability in the basin and understanding the hydrological responses of the basin to both glacier and climate change. The comprehensive dataset for the PGRB is a valuable and exceptionally long-standing testament to the impacts of climate change on the cryosphere in the high-mountain environment. The dataset is publicly available from Federated Research Data Repository at 10.20383/101.0259 (Pradhananga et al., 2020). [ABSTRACT FROM AUTHOR]

Reconstructing the topography of shallow underwater environments using Structure-from-Motion—Multi View Stereo (SfM-MVS) techniques applied to aerial imagery from Unmanned Aerial Vehicles (UAVs) is challenging, as it involves nonlinear distortions caused by water refraction. This study presents an experiment with aerial photographs collected with a consumer-grade UAV on the shallow-water reef of Fuvahmulah, the Maldives. Under conditions of rising tide, we surveyed the same portion of the reef in ten successive flights. For each flight, we used SfM-MVS to reconstruct the Digital Elevation Model (DEM) of the reef and used the flight at low tide (where the reef is almost entirely dry) to compare the performance of DEM reconstruction under increasing water levels. Our results show that differences with the reference DEM increase with increasing depth, but are substantially larger if no underwater ground control points are taken into account in the processing. Correcting our imagery with algorithms that account for refraction did not improve the overall accuracy of reconstruction. We conclude that reconstructing shallow-water reefs (less than 1 m depth) with consumer-grade UAVs and SfM-MVS is possible, but its precision is limited and strongly correlated with water depth. In our case, the best results are achieved when ground control points were placed underwater and no refraction correction is used. [ABSTRACT FROM AUTHOR]

The objective of this work is to conduct a detailed mapping of the Héðinsdalsjökull foreland, northern Iceland (65°39'N, 18°55'W). This cirque currently shows a variety of glacial and periglacial landforms derived from a complex deglaciation. Mapping was performed combining traditional hand-drawn and digital mapping. A hand-drawn sketch was georeferenced in ArcMap 10.7.1, supported on an aerial photograph (year 2000). Its vectorization, symbolization and final design were done in the computer-aided design (CAD) software MicroStation Connect. Complementary high-resolution Digital Surface Models were obtained from historical aerial photographs and ground-view field photographs through the application of Structure from Motion (SfM) photogrammetry. To improve the topographic expression of the geomorphological map, a photorealistic 3D view has been generated. The final map highlights the complexity of the foreland and the coexistence existence of a range of different units and landforms. The map will ease future studies on the transformation of receding glaciers. [ABSTRACT FROM AUTHOR]

Multi-source mudslides are common in the Daunia Apennines, i.e., the Apulian sector of the Southern Apennines of Italy, and play an important role in the historical evolution of the landscape, with significant impact on the social and economic activities of the area. They also represent the most relevant geological hazard along the front of the Apennine Chain and expose to a considerable risk the local population and infrastructures. The outer sector of the Daunia Apennines is part of the foreland thrust belt system, made up of fissured fine-grained materials, belonging to the Daunia tectonic unit formations. Concerning landslide typology, the most frequent slope movements are represented by flows and composite mudslides, the latter typically starting as slumps evolving from flows. This paper deals with the production of landslide activity maps of three case studies of composite mudslides from the front of the Daunia Apennines. The maps were produced integrating traditional interpretation of multi-year aerial photograph coverage and field surveys with the available digital elevation models to analyze surface morphology. Each landslide activity map corresponds to multi-temporal landslide inventories compiled for the last 15–20 years. This paper outlined that in the last 20 years the front of the Daunia Apennines underwent a significant reactivation of slope failure phenomena after years of quiescence, or of limited activity. The three case studies clearly confirm that: (i) the active portions of the mudslides are located inside or near preexisting slope failures, and (ii) the spatial distribution of instability phenomena is strictly dependent upon the presence of older, larger and dormant, phenomena. Landslide activity maps are an important tool for the evaluation of landslide susceptibility and hazard in the study area, and for quantitative geomorphological analyses it aimed at understanding the long-term geomorphological evolution of this portion of the Southern Apennines. Moreover, we argue that high-quality multi-temporal inventories could have positive effects on all derivative products and analyses, including erosion studies and landscape modeling, susceptibility and hazard assessments, and risk evaluations as well. [ABSTRACT FROM AUTHOR]

Due to modern climate change and globally increasing atmospheric and ocean temperatures, glaciers are retreating worldwide thus more and more affecting the environment. Their global impact raises concerns and the need to understand the dynamic behavior of glaciers and the complex interaction between the cryosphere, atmosphere, hydrosphere, and lithosphere. Since 2014 scientists from the University of Latvia have contributed to the studies of modern glaciers and polar environment by conducting scientific expeditions to the Arctic and Antarctic and by developing polar science studies in Latvia. Cooperation has been established with several institutes in Latvia and abroad including the National Antarctic Scientific Center who owns the Akademik Vernadsky station in Antarctica and the Nicolaus Copernicus University in Toruń who manages the Polar Station “Hahut” located in Svalbard. The article describes the chronology and locations, methodology and the main results and their importance from studies performed on scientific expeditions to Iceland, Greenland, Svalbard and Antarctica. The specific research fields include studies of glacier geometry and mass changes, thermal structure, drainage systems, and subglacial topography. The developed methodology allows performing high-precision measurements with ground-penetrating radar on glaciers. In combination with the acquisition of aerial photographs by unmanned aerial vehicles, this approach allows the construction of digital elevation models of glacier surface and bed. In addition, collaboration with scientists from the various other scientific fields has resulted in studies related to persistence of pollutants in polar regions, characterization of microbial diversity and other ecological issues. In order to further develop the field of polar research in Latvia, the authors encourage the establishment of a long-term national polar research program and recommend that Latvia join the Antarctic Treaty and the Arctic Council as an observer country. [ABSTRACT FROM AUTHOR]

Salt marshes are valuable ecosystems, and there is concern that increases in the rate of sea level rise along with anthropogenic activities are leading to the loss of vegetated habitat. The area of vegetated marsh can change not only through advance and retreat of the open fetch edge, but also due to channel widening and contracting, formation and drainage of interior ponds, formation and revegetation of interior mud flats, and marsh migration onto upland areas, each of which is influenced by different processes. This study used historical aerial photographs to measure changes in the extent of vegetated marsh over approximately 70 years at study marshes located in three long-term ecological research (LTER) sites along the US East coast: Georgia Coastal Ecosystems (GCE), Virginia Coast Reserve (VCR), and Plum Island Ecosystems (PIE). Marsh features were categorized into vegetated marsh, ponds, interior mud flats, and channels for three time periods at each site. The three sites showed different patterns of change in vegetated marsh extent over time. At the GCE study site, losses in vegetated marsh, which were primarily due to channel widening, were largely offset by channel contraction in other areas, such that there was little to no net change over the study period. The study marsh at VCR experienced extensive vegetated marsh loss to interior mud flat expansion, which occurred largely in low-lying areas. However, this loss was counterbalanced by marsh gain due to migration onto the upland, resulting in a net increase in vegetated marsh area over time. Vegetated marsh at PIE decreased over time due to losses from ponding, channel widening, and erosion at the open fetch marsh edge. Digital elevation models revealed that the vegetated areas of the three marshes were positioned at differing elevations relative to the tidal frame, with PIE at the highest and VCR at the lowest elevation. Understanding the patterns of vegetation loss and gain at a given site provides insight into what factors are important in controlling marsh dynamics and serves as a guide to potential management actions for marsh protection. [ABSTRACT FROM AUTHOR]

Questions surrounding the emergence of highly mobile nomadic pastoralism and the origins of the associated Scythian material culture have a long history in Eurasian steppe archaeology, but advances in knowledge have been hindered by a lack of data. Here we present new findings on the Early Iron Age royal burial mound Tunnug 1 in Tuva. While the site belongs to the same cultural tradition as Arzhan 1, the conceptual roots of the funerary ritual architecture can be traced to precursors in the Mongun Taiga culture and the Mongolian deer stone khirigsuur complex. The clay architecture uncovered at Tunnug 1 does not find any regional comparisons and possibly hints towards a western Central Asian contribution to the formation of the earliest Scythian horizon. Our research demonstrates the value of a multi-disciplinary approach to documenting monumental earthen architecture, including technical approaches (satellite imagery, aerial photographs, 3D models, digital elevation models, geophysics, and radiocarbon dating) with an analysis of construction material and associated finds. [ABSTRACT FROM AUTHOR]

Airborne laser scanning (ALS) is generally known as the most accurate and primary source providing the 3D structure of forest canopy model (CHM) information; however, in many countries, it is not updated as needed for continuous forest management planning due to its high costs. Image-based point clouds derived from airborne stereo aerial photographs, space-borne stereo very high-resolution WorldView-2, and TerraSAR-X add-on for Digital Elevation Measurement (TanDEM-X) can also be used for the generation of the CHM. In this study, we compared the performance of three types of 3D data, i.e. stereo aerial photographs, stereo very high-resolution WorldView-2, and TanDEM-X for the retrieval of forest CHM. Digital surface models (DSMs) generated from image-based point clouds produced from stereo aerial photographs and stereo WorldView-2 using image-matching algorithms and from TanDEM-X data using interferometry. Finally, three types of CHMs generated by subtracting ALS-based digital terrain model (DTM) from the above three DSMs. Plot-level heights and density metrics extracted from the CHMs and regressed with the field-based Lorey's mean, and maximum height. Stereo aerial photographic CHM showed the most accurate results with root-mean-square error (RMSE) = 1.71 m, followed by high-resolution stereo WorldView-2 with RMSE = 2.04 m, and TanDEM-X with RMSE = 2.13 m, respectively. Also, for maximum height, we obtained higher accuracy for image-based point clouds with RMSE = 2.33 m, followed by high-resolution stereo WorldView-2 with RMSE = 2.71 m, and TanDEM-X with RMSE = 2.81 m, respectively. Our overall finding indicated that stereo aerial photography is the most accurate option followed by stereo very high-resolution WorldView-2 and TanDEM-X data for estimating forest heights. The study shares valuable information for the generation and regular update of forest structure information in the presence of pre-existing ALS DTM. [ABSTRACT FROM AUTHOR]

Historical aerial photographs are an invaluable tool in shoreline mapping and change detection in coastal landscapes. We evaluate the extent to which structure‐from‐motion (SfM) photogrammetric methods can be applied to quantify volumetric changes along sandy beaches, using archival imagery. We demonstrate the application of SfM‐derived digital surface models (DSMs) at East Beach and Lady Bay in southwest Victoria, Australia, using photographic datasets taken in 1969, 1977 and 1986, and compare them to LiDAR‐derived DSMs acquired at both sites in 2007. The SfM approaches resulted in two entire and two partial suitable DSMs out of six datasets. Good‐quality DSMs were spatially continuous with a good spread of ground control points (GCPs) near the beach at Lady Bay, whereas unsuitable DSMs were mostly restricted by poor distribution and number of GCPs in spatially segmented areas of East Beach, due to limited overlapping of images, possible poor quality of GCPs and also the propagation of errors in the derived point clouds. A volume of approximately 223 000 ± 72 000 m3 was deposited at Lady Bay between 1969 and 2007, despite minimal erosion observed near the breakwater. The partially suitable dataset of East Beach indicated that beach erosion of at least 39 m3 m−1 occurred immediately to the east of the seawall after 1977. We also discuss the drawbacks and strengths of SfM approaches as a benchmark of historical erosion assessments along sandy beaches. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this work, we present a geomorphological map of the 'Canale di Pirro' polje, located in the central part of Apulia region, Southern Italy, among the most interesting karst landforms in the Mediterranean Basin. This area is characterized by a remarkable underground system of caves, where the so-called 'Inghiottitoio di Masseria Rotolo' reaches a depth of 324 m, thus being the deepest known cave in Apulia. The polje is bounded on both sides by tectonically controlled ridges, showing an overall length of some 12 km. The map of the area is produced starting from the interpretation of aerial photographs, the integration of the digital elevation model analysis and field surveys, in order to obtain a correct distribution of landforms and fluvial processes. Furthermore, karst depressions, conical hills, erosional gullies, alluvial fans and tectonic structures have been also identified and reported in the map. [ABSTRACT FROM AUTHOR]

Paddy fields in the Osaka Prefecture were heavily flooded by heavy rain in July 2018 due to levee breaches. To estimate the flooded area and water level, it was necessary to combine aerial- and ground-based surveying. Accordingly, aerial photographs of the flooded area were taken on the day after the heavy rain. In this study, we developed a digital surface model (DSM) of the flooded area using the structure-from-motion (SfM) software, which can produce three-dimensional (3D) models based on multiple aerial photographs and multiple ground control points (GCPs). Using the global navigation satellite system (GNSS), we surveyed the target area to observe the 3D coordinate values of the GCPs. The DSM of the flooded area could be made by the SfM with the aerial photographs and GCPs. The DSM was input into the geographic information system to analyze the flooded area and water level. The water levels were calculated from the differences between the DSM and the digital elevation model (DEM). We used airborne laser surveying to build the DEM because it provides higher accuracy than the SfM software. To check the accuracy of the DSM, we compared the elevations of the DSM on the ground points of non-flooded areas with those of the DEM, and the differences were found to be less than 0.2 m. Then, the water levels on the actual water level observation points were compared to verify their accuracy, and the differences were found to be less than 0.4 m. The flooded area was found by overlaying the water level on the existing map. [ABSTRACT FROM AUTHOR]

A landslide inventory is indispensable for determination of landslide susceptibility, hazard, risk assessment and disaster mitigation strategies. These inventories were traditionally developed using manual digitization of remote sensing images and aerial photographs, and pixel-based image classification. Recently, Object-Based Image Analysis (OBIA) supersedes visual interpretation and pixel-based methods. OBIA utilizes spectral, textural, contextual, morphological and topographical information in remote sensing images. However, OBIA-based landslide detection methods are often designed for specific areas and remote sensing dataset. The aim of this study is to evaluate the transferability of three published OBIA landslide detection methods for semi-automated landslide detection in the Himalaya mountainous region of northern Pakistan. A SPOT-6 multi-spectral image with Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) Digital Elevation Model (DEM) derivatives, i.e. slope, aspect, hill-shade, relief, elevation and stream network are used for landslide detection using eCognition developer software. The three published methods scale parameters for image segmentation and parameter thresholds are evaluated first. It is observed that the aforementioned methods are not directly applicable to our study area and remote sensing datasets. Therefore, an alternate (proposed) method is developed for semi-automated landslide detection. Accuracy assessment of the selected methods and proposed method is assessed by Precision, Recall and F1 measures. Using the proposed method, a total of 357 landslides are detected with 91.46% Precision, 93.31% Recall and 92.38% F1 measure accuracy. [ABSTRACT FROM AUTHOR]

Many existing village maps in Indonesia are available without spatial references, including in Pandanrejo village in Kaligesing Sub-district, Purworejo District, Central Java. To date, the available village map of the Pandanrejo is sketches map which potentially overlaps with the area of adjacent villages. In this study, we used a commercial drone DJI Phantom 4 for generating a high precision orthophoto to create the exact boundaries and land use information of the Pandanrejo village. The drone captured the aerial images from an altitude of approximately 100 m and automatically take an image every 3 seconds giving an overlap of each image around 70% of each pair of neighboring images. By this mission plan, the drone collected of about 1,312 aerial photographs. In order to obtain better geo-referencing results, eleven Ground Control Points (GCPs) distributed over the study area were obtained by GNSS geodetic tools. Furthermore, the Structure from Motion (SfM) algorithm was used to generate point clouds, digital surface models, and digital orthophoto model. These processes were carried out by using Agisoft PhotoScan software completing 10 steps in the workflow starting from adding drone images to the software to building orthomosaic as a basis for a digital orthophoto model. We then analyzed the errors of the resulted orthophoto map by comparing between the ratio of village boundary length to the total village area from drone mapping and terrestrial mapping using GNSS geodetic. The results showed that the drone mapping has successfully produced the village boundary map of the Pandanrejo village (i.e. a boundary length 7,473.2 m and an area 2.18 km2 ) that is comparable with the result of terrestrial area mapping corrected by GNSS geodetic. In addition, the drone has also successfully mapped the village land use with a total accuracy of 100% accurate. With these results, we suggest drone technology as an alternative method besides a traditional terrestrial method to create a definite village boundary and land use map to support the implementation of Indonesia Law No. 6 of 2014. [ABSTRACT FROM AUTHOR]

The majority of shore platforms form in rocks that are characterised by layered stratigraphy and pervasive jointing. Plucking of weathered, joint and bed bounded blocks is an important erosion process that existing models of platform development do not represent. Globally, measuring platform erosion rates have focused on microscale (< 1 mm) surface lowering rather than mesoscale (0.1‐1 m) block detachment, yet the latter appears to dominate the morphological development of discontinuity rich platforms. Given the sporadic nature of block detachment on platforms, observations of erosion from storm event to multi‐decadal timescales (and beyond) are required to quantify shore platform erosion rates. To this end, we collected aerial photography using an unmanned aerial vehicle to produce structure‐from‐motion‐derived digital elevation models and orthophotos. These were combined with historical aerial photographs to characterise and quantify the erosion of two actively eroding stratigraphic layers on a shore platform in Glamorgan, south Wales, UK, over 78‐years. We find that volumetric erosion rates vary over two orders of magnitude (0.1‐10 m3 yr‐1) and do not scale with the length of the record. Average rates over the full 78‐year record are 2‐5 m3 yr‐1. These rates are equivalent to 1.2‐5.3 mm yr‐1 surface lowering rates, an order of magnitude faster than previously published, both at our site and around the world in similar rock types. We show that meso‐scale platform erosion via block detachment processes is a dominant erosion process on shore platforms across seasonal to multi‐decadal timescales that have been hitherto under‐investigated. © 2019 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd [ABSTRACT FROM AUTHOR]

The Assi river in Varanasi, Uttar Pradesh, India, is now a small, local, ephemeral floodplain tributary of River Ganga, with a length of about 8 km and catchment area of about 22 km2. It has also turned into a filthy drain. There are evidences in the form of palaeochannels, through patterns of water bodies and settlements along them, to suggest the origin of Assi river near Allahabad flowing through a distance of about 120 km up to Varanasi to meet the Ganga. There is also the possibility that Assi started as a takeoff from River Ganga and flowed as a Yazoo stream. Through on-screen digitization from high and medium-resolution remote sensing data - BHUVAN and Google Earth, CORONA aerial photographs, IRS P6 LISS-IV, Landsat 1, 3, 5, 7, 8 - and a number of cross profiles from SRTM 30 m digital elevation model (DEM), palaeochannel of Assi has been delineated. Also, a 1 m DEM was generated for the present Assi catchment area from about 5000 DGPS points to present proof that the present Assi is a misfit in once a wider valley shaped by heavy discharge coming from a greater length of channel and a larger catchment area. [ABSTRACT FROM AUTHOR]

Landscapes have been photographed dozens of times at scales ca. 1/25,000 and better since World War II. Scans are distributed freely online (e.g. remonterletemps.ign.fr). In parallel, Structure-from-Motion (SFM) software made photogrammetric processing easy to non-specialists. Yet puzzling questions crop up to use both: (i) Can raw scans be used as is? (ii) Can Ground Control Points (GCP) and checkpoints be safely collected from a web portal? (iii) How many parameters are sufficient for camera interior orientation? (iv) Are single flight camera networks sufficient to constrain camera models compared to multiple flights? (v) Are photogrammetric Digital Surface Models (DSM) fit for quantifying landslide activity? Processing of scanned black-and-white 1/27,000 photographs from IGN flown in May 1978 over Cirque de Salazie in La Réunion Island answer these questions. We find that raw scanned photographs need translation, rotation and cropping to match the camera reference frame. GCP and Check point coordinates collected on geoportail.gouv.fr with assumed accuracy of 10 m, achieved ca. 7 m accurate SFM registration. The optimal camera model uses only 4 parameters: f, cx, cy and K1. Compared to a 2015 lidar Digital Terrain Model (DTM), the 0.66 m/pixel DSM of 1978 has a median deviation of −1.39 m ± 3.34 m (Median Absolute Deviation) which is comparable to GCP quality. Elevation difference more importantly reveals, for the first time, the 37 years and 13 cyclones cumulated landslides pattern on Cirque de Salazie. Photographic archives hold decades-long 3D history. SFM is a game changer for landslide risk mitigation planning. [ABSTRACT FROM AUTHOR]

The monitoring of morphologic changes in high-mountain environments is an important, but complex task. Terrestrial as well as airborne laser scanning (TLS and ALS) and digital photogrammetry (DP) using Unnamed Aerial Vehicle (UAV) can determine recent variations. In contrast, changes that occurred 20 or more years ago, need generally the application of DP and historic aerial photograph. We compared these four geomatic techniques and the resulting digital elevation models (DEM) that ranged over a 70-year time span (1946–2016). The accuracy of the different models and also the effect of different cell size were analysed. The accuracy analysis of the resulting DEMs shows important drawbacks, when historic aerial photographs are used. In these DEMs, the error in elevation can be important and a detailed analysis of morphologic changes is limited. Nowadays, the combination of DP and UAV is the technique with best cost-benefit ratio, although TLS could reveal similar precision. However, the application of TLS is restrained by the complex morphology and the presence of vegetation, which produce many shadows. Finally, the erosion rate was determined in our catchment. The resulting values range between 0.06 and 0.16 m3/m2/y, which coincides rather well with data observed in other studies. [ABSTRACT FROM AUTHOR]

The Gaick is an enigmatic glaciated landscape in the Central Grampians, Scotland, dominated by an expansive dissected plateau. Previous studies have postulated widely differing interpretations of the glacial landforms and current understanding of the glacial events in this area is partly restricted by the absence of detailed glacial geomorphological mapping. To address this issue, we present a comprehensive 1: 46,000-scale glacial geomorphological map, covering an area of ∼520 km2. A combination of detailed field mapping and interpretation of aerial photographs and Digital Surface Models (DSMs) has revealed a variety of glacial, periglacial and fluvial landforms, including an abundance of moraines and meltwater channels within valleys. We also identify a glacial sediment-landform assemblage, dissected glaciogenic material, that has not previously been reported in the Scottish Highlands. The geomorphological map provides the necessary foundation for elucidating the extent, dynamics and timing of former glaciation in the area. [ABSTRACT FROM AUTHOR]

The behavior of the shelly beach ridge system forming a more or less continuous barrier lying along the southern coast of the hypertidal Mont-Saint-Michel bay (NW France) is examined using a set of various data including aerial photographs since 1947, sediment cores collected in back-barrier salt marshes, ground penetrating radar profiles, and differential digital elevation models (DEMs). The latter shows that since the middle of the 20th century, the tidal flats extending in front of the ridge system experience erosion and accretion that alternate spatially according to cross-shore corridors. The shelly ridges are better developed on line with the erosional bands. The reasons for this erosion/accretion compartment pattern are not totally elucidated. It probably results from the combined influence of shellfish farms, tidal channels and reef present on the tidal flats on wave and current dynamics. At the decadal to pluri-decadal scale, the shelly beach ridge system behavior as well as its internal organization can partly be related to the fluctuations of hydrodynamic conditions controlled by the 18.6 years nodal tidal cycle. Periods of intense landward migration alternate with periods of relative stability during the peak and the trough of the cycle respectively. This general scheme is complicated due to variations in storm wave dynamics. The most morphogenic events happen potentially during coinciding nodal cycle peaks and enhanced storminess. Such conditions actually occurred around 1995-2000, resulting in the most prominent washover fan deposit preserved within the back-barrier infilling successions. These sediment successions evidence as well that no beach ridge system older than the 19th century is preserved in front of the Medieval dike built during the 11th century on a relict beach ridge, and on which the present-day system is backed. We suggest that the enhanced storminess conditions of the Little Ice Age provoked the reworking of beach ridges formed between the 11th and 19th centuries. Changes in quantity and type of mollusk shells, related to the shellfish farming development during the 20th century are also thought to have had positive consequences on the barrier building and stability. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Turkish Research Institute / Atatürk Üniversitesi Türkiyat Arastirmalari Enstitüsü Dergisi is the property of Ataturk University Coordinatorship of Scientific Journals and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Currently on the world market there are several models and manufacturers of RPAS-UAV. This equipment made it possible to complete the entire flow of the photogrammetric mapping process in teaching for the students of the Cartographic Engineering course. In the Institute of Geosciences, this course already counted on the photogrammetric stations, equipped with hardware for 3D visualization (graphic card, high-speed monitors and stereoscopic vision glasses), photogrammetric software for data processing, and equipment for geodetic measurement control points. Before the acquisition of the RPAS, for the accomplishment of the academic works, it was necessary to buy or to look for in donations from companies of aerial photographs, that did not always correspond to an area of scientific interest. In addition, the scenes in the photos were not current, and it was impossible to have control points that were pre-signalized. From the availability of the RPAS in the University, the students began to have more interest by Photogrammetry in their professional end of coursework and throughout the disciplines. It became possible to carry out in practice all the processes involved in the mapping of nearby areas of interest, from the planning to the generation of photogrammetric products, such as the generation of DTM (Digital Terrain Model), DEM (Digital Elevation Model), orthophotomaps and extraction of features. In addition to products related to the 3D mapping of terrains, mainly through the RPAS of rotating wings, there was also the possibility of mapping and reconstructing 3D structures, such as buildings of historical monuments. [ABSTRACT FROM AUTHOR]

Glaciers of the Svalbard archipelago react very rapidly to climate change in the polar environment. Combining the study of aerial photographs, digital elevation models and in situ measurements, it is possible to measure glacier geometric changes. Apart from the standard remote sensing data evaluation we focus on in situ measurements by ground penetrating radar. This study calculates length, area, volume and elevation changes of three glaciers in Dickson Land, central Spitsbergen, during the period 1990–2015. Ground penetrating radar surveys indicate ice thickness, which was used for calculating the volume and the bed topography of the glaciers. The mean ice thickness ranges from 21.2 to 52.4 m. Between 1990 and 2015, the glacierized area decreased from 5.37 ± 1.02 km2 to 4.45 ± 0.25 km2 (- 17.5%) and the volume reduced from 309.93 ± 4.75 mil m3 to 215. 44 ± 1.27 mil m3 (- 30.5%). The mean surface elevation decreased by 23.0 ± 8.4 m (Bertilbreen), 22.3 ± 10.2 (Ferdinandbreen) and 10.7 ± 7.8 m (Elsabreen). The average surface elevation (0.4 ± 0.3 to 1.0 ± 0.4 m a−1) and volumetric (- 0.22 ± 0.02 to - 3.61 ± 0.12 mil m3 a−1) changes correspond to values reported from this and other regions of Svalbard. [ABSTRACT FROM AUTHOR]

In this paper we present a reconstruction of the kinematics of the Tschadinhorn rock glacier using multitemporal conventional (metric) aerial photographs (1954-2015) and additional non-metric aerial photographs (2016, 2017) taken with in-house unmanned aerial vehicles (UAVs). A rotary-wing aircraft (hexacopter twinHEX v.3.0) was used in 2016 and a fixed-wing aircraft (QuestUAV) in 2017. The historical image data was acquired from the Austrian Federal Office of Metrology and Surveying (BEV). Both a digital orthophoto (DOP) and a digital terrain model (DTM) were computed for each given epoch. Precise georeferencing of the image data was carried out in the Austrian Gauss-Kruger M31 coordinate system using available aerotriangulations (ATs) of BEV and additional ground control points (GCPs) measured geodetically during both UAV campaigns. Change detection analysis provided multi-temporal 2D flow velocity fields. Subsequently, these data were collated to produce a simpler velocity graph showing clearly the temporal evolution of the flow velocity of Tschadinhorn rock glacier: A maximum mean annual flow velocity of 3.28 m/year was obtained for 2014-2015, while the lowest annual flow velocity of 0.16 m/year was observed for 1969-1974. The velocity graph also revealed that 1954-2009 was characterized by generally moderate activity (0.16 - 0.79 m/year) and that much higher flow velocities have prevailed since 2009. The present value for 2016-2017 is 1.92 m/year. [ABSTRACT FROM AUTHOR]

New field work, combined with analysis of high-resolution aerial photographs, digital elevation models, and satellite imagery, has identified an active fault that is traceable for ∼90 km across the Seymchan Basin and is part of the Ulakhan fault system, which is believed to form the Okhotsk–North America plate boundary. Age dating of alluvial fan sediments in a channel system that is disturbed by fault activity suggests the current scarp is a result of a series of large earthquakes (≥Mw7.5) that have occurred since 11.6±2.7 ka. A possible channel feature offset by 62±4 m associated with these sediments yields a slip rate of 5.3±1.3 mm yr -1 , in broad agreement with rates suggested from global plate tectonics. Our results clearly identify the Ulakhan fault as the Okhotsk–North America plate boundary and show that tectonic strain release is strongly concentrated on the boundaries of Okhotsk. In light of our results, the likelihood of recurrence of Mw7.5 earthquakes is high, suggesting a previously underestimated seismic hazard across the region. [ABSTRACT FROM AUTHOR]