High-resolution Topographic Maps Research Articles

High-resolution UAV maps of the Gobi Desert provide new insights into the Upper Cretaceous of Mongolia

The Gobi Desert of southern Mongolia is home to an incredibly rich record of dinosaurs and other vertebrate fossils from the latest Cretaceous Period. Together, more than a dozen sites in several basins have produced one of the richest palaeofaunas known from this interval anywhere in the world. Most of this diversity has been recovered from the fluvial deposits of the Nemegt Formation. Despite historic and ongoing research in southern Mongolia, accurate maps and geological data for the main fossil sites are still lacking, limiting our ability to investigate how local palaeoecological dynamics influenced Nemegt taxa, their geographic distribution, and their evolutionary patterns. One of these sites, Guriliin Tsav, has produced more than a hundred significant fossil specimens to date, but still remains one of the lesser known Nemegt localities. In part this is because many expeditions have instead focused on the nearby Bügiin Tsav, one of the largest and richest localities for the Nemegt Formation. To address this gap, a project was initiated in 2018 to produce a high-resolution topographic map of Guriliin Tsav using Unmanned Aerial Vehicles (UAV), and consequently, to plot the geographic and stratigraphic distributions of palaeontological resources on this map. In so doing, we also collected stratigraphic and taphonomic data from the area, allowing for the first detailed palaeoecological interpretation of Guriliin Tsav and a comparison with other localities of southern Mongolia. Here we present the results of this project, and also discuss new topographic and stratigraphic data from Bügiin Tsav. This sheds new light into the temporal and geographic distribution of vertebrate taxa in the latest Cretaceous of Mongolia.

Centennial loss of lake wetlands in the Yangtze Plain, China: Impacts of land use changes accompanied by hydrological connectivity loss

Humans have played a fundamental role in altering lake wetland ecosystems, necessitating the use of diverse data types to accurately quantify long-term changes, identify potential drivers, and establish a baseline status. We complied high-resolution historical topographic maps and Landsat imagery to assess the dynamics of the lake wetlands in the Yangtze Plain over the past century, with special attention to land use and hydrological connectivity changes. Results showed an overall loss of 45.6 % (∼11,859.5 km2) of the lake wetlands over the past century. The number of lakes larger than 10 km2 decreased from 149 to 100 due to lake dispersion, vanishing, and shrinkage. The extent of lake wetland loss was 3.8 times larger during the 1930s–1970s than that in the 1970s–1990s. Thereafter, the lake wetland area remained relatively stable, and a net increase was observed during the 2010s–2020s in the Yangtze Plain. The significant loss of lake wetland was predominately driven by agricultural activities and urban land expansion, accounting for 81.1 % and 4.9 % of the total losses, respectively. In addition, the changes in longitudinal and lateral hydrological connectivity further exacerbated the lake wetland changes across the Yangtze Plain through isolation between lakes and the Yangtze River and within the lakes. A total of 130 lakes have been isolated from the Yangtze River due to the construction of sluices and dykes throughout the Yangtze Plain, resulting in the decrease in the proportion of floodplain marsh from 28.3 % in the 1930s to 8.0 % in the 2020s. Furthermore, over 260 sub-lakes larger than 1 km2 (with a total area of 1276.4 km2) are experiencing a loss of connectivity with their parent lakes currently. This study could provide an improved historical baseline of lake wetland changes to guide the conservation planning to wetland protection and prioritization area in the Yangtze Plain.

Degradation of the 2014–2015 Holuhraun vent-proximal edifice in Iceland

AbstractThe earliest stages of volcanic vent degradation are rarely measured, leaving a gap in the knowledge that informs landform degradation models of cinder cones and other monogenetic vent structures. We documented the initial degradation of a 500-m-long spatter rampart at the primary vent of the 2014–2015 Holuhraun eruption in northern Iceland with high-resolution topographic change maps derived from terrestrial laser scanning (TLS) and photogrammetric surveys using an unoccupied aircraft system (UAS). Topographic differencing shows a total negative volume change of 42,637 m3, and a total positive volume change (basal deposition) of 10,304 m3 (primarily as deposition at the base of steeply sloping surfaces). Two distinct styles of volume changes were observed on the interior and exterior of the spatter rampart. Material on the interior of the vent was removed from oversteepened slopes by discrete rockfalls, while diffusive processes were qualitatively evident on the exterior slopes. We propose a novel conceptual landform evolution model for spatter ramparts that combines rockfall processes on the interior walls, diffusive gravitational sliding on the exterior slopes, and incorporates cooling contraction and compaction over the entire edifice to describe the observed modes of topographic change during the onset of degradation. Potential hazards at fresh spatter ramparts are rockfalls at high slope areas of the vent interior walls where contacts between spatter clasts are prone to weakening by fumarolic activity, weathering, and settling. To capture such hazards, our data suggest a cadence for monitoring changes yearly for the first few years post-eruption, and at longer intervals thereafter.

Atmosphere-aware photoclinometry for pixel-wise 3D topographic mapping of Mars

High-resolution topographic mapping is essential for scientific investigations and operational exploration of planets, such as Mars. Photoclinometry, which uses light scattered from a surface to reconstruct 3D topography, can retrieve subtle topographic details from monocular images. However, its performance is affected by the atmosphere of Mars, which alters surface reflectance mechanisms due to the scattering and absorption by aerosols. Therefore, specific treatments accounting for these atmospheric effects are needed to enable photoclinometric mapping of Mars. This paper presents a novel photoclinometric approach incorporating a radiative-transfer model of atmospheric scattering effects for pixel-wise 3D reconstruction of the Martian surface. The approach requires a high-resolution image, a corresponding coarse-resolution digital elevation model (DEM), and information of the optical depth as inputs. A radiative transfer model adapted to the Martian atmosphere is used to account for the atmospheric effects. The approach also allows directly adopting optical depth estimates from a global database (e.g., the Mars Climate Database). The approach was validated using different types of Mars orbiter images collected by cameras on-board the Mars Reconnaissance Orbiter and the Tianwen-1 Orbiter. The results indicate that the approach can achieve a geometric accuracy (in terms of root-mean-squared error (RMSE) of the elevation) of approximately 2 pixels of the image resolution and significantly enhances topographic details. In addition, we evaluated the approach using different settings for the optical depths and spatial resolutions of the input DEMs. The results show that overestimating the optical depth leads to overestimation of topographic amplitudes (e.g., deeper craters). On the other hand, underestimating the optical depth by the same amount as overestimation leads to a smaller increase in the RMSE. Moreover, coarsening the resolution of an input DEM increases the RMSE of the photoclinometric results. Nevertheless, photoclinometry improves both the RMSE and the resolution of the input DEM. This new approach serves as an effective means for applying photoclinometry for pixel-wise 3D topographic mapping of the Martian surface. This will facilitate exploitation of the large number of high-resolution monocular images of Mars in 3D topographic mapping of the planet.

Sharp, high numerical aperture (NA), nanoimprinted bare pyramid probe for optical mapping.

The ability to correlate optical hyperspectral mapping and high resolution topographic imaging is critically important to gain deep insight into the structure-function relationship of nanomaterial systems. Scanning near-field optical microscopy can achieve this goal, but at the cost of significant effort in probe fabrication and experimental expertise. To overcome these two limitations, we have developed a low-cost and high-throughput nanoimprinting technique to integrate a sharp pyramid structure on the end facet of a single-mode fiber that can be scanned with a simple tuning-fork technique. The nanoimprinted pyramid has two main features: (1) a large taper angle (∼70°), which determines the far-field confinement at the tip, resulting in a spatial resolution of 275nm, an effective numerical aperture of 1.06, and (2) a sharp apex with a radius of curvature of ∼20nm, which enables high resolution topographic imaging. Optical performance is demonstrated through evanescent field distribution mapping of a plasmonic nanogroove sample, followed by hyperspectral photoluminescence mapping of nanocrystals using a fiber-in-fiber-out light coupling mode. Through comparative photoluminescence mapping on 2D monolayers, we also show a threefold improvement in spatial resolution over chemically etched fibers. These results show that the bare nanoimprinted near-field probes provide simple access to spectromicroscopy correlated with high resolution topographic mapping and have the potential to advance reproducible fiber-tip-based scanning near-field microscopy.

Highly Resolved Topography and Illumination at Mercury’s South Pole from MESSENGER MDIS NAC

Mercury’s south polar region is of particular interest since Arecibo radar measurements show many high-reflectance regions consistent with ice deposits. However, current elevation information in Mercury’s southern hemisphere is not sufficient to perform detailed modeling of the illumination and thermal conditions at these radar-bright locations and to constrain properties of the volatiles potentially residing there. In this work, we leverage previously existing elevation maps of Mercury’s surface from stereo-photogrammetry at 665 m pix−1, Mercury Dual Imaging System Narrow Angle Camera images, and Shape-from-Shading tools from the Ames Stereo Pipeline, to provide the first high-resolution topographic maps of the south pole with a resolution of 250 m pix−1 poleward of 75°S. We show that the increased resolution and level of detail provided by our new elevation model allow for a more realistic recovery of illumination conditions in Mercury’s south polar region, thus opening the way to future thermal analyses and for the characterization of potential ice and volatile deposits. We compare both the old and new topographic models to the Mercury Dual Imaging System Narrow Angle Camera images to show the higher level of fidelity with our products, and we assess the improved consistency of derived permanently shadowed regions with reflectance measurements by Arecibo’s antennas.

Sunlit pathways between south pole sites of interest for lunar exploration

The lunar poles are of high interest to human and robotic exploration for their exploration potential to host volatiles useful for scientific and commercial purposes in cold permanently shadowed regions and for the rare highly-illuminated regions that can support exploration efforts. We investigate if the complex and dynamic lighting is amenable to long traverses between these sparsely-distributed, distant sites of interest. We use accurate high-resolution topographic maps of the south polar region to compute the traverse paths, and we simulate the time-varying illumination conditions along these over long time periods to determine whether such trips are possible while remaining nearly entirely sunlit. We find that long-distance sunlit pathways are possible but long in duration. These can be further optimized, and potentially significantly shortened given specific survival capabilities, such as driving through short periods of shadows.

Monte Carlo simulation for background noise study of the Wudalianchi volcanic density imaging

In our muon radiography experiment on the Wudalianchi volcano in northeastern China, the muon flux was overestimated and the volcano density was underestimated due to the contamination by background noise. In our past simulation work on background noise, we did not construct the volcano model, we just simply used the volcanic high-resolution topographic map data and the cosmic ray particle source data to obtain the penetrating muon energy spectrum. In order to study the background noise and volcanic density more accurately and in detail, we used the GEANT4 tool to construct a virtual volcano and a virtual detector, and combined the cosmic ray shower library (CRY) to simulate the interaction between the volcano and cosmic ray particles. The results show that the background noise in volcano muon radiography is mainly composed of particles with low-energy (less than 1GeV). According to the elimination device to reduce the background particles, the volcano density map we obtained is closer to the simulated value than the map before eliminating. This research has implications for our next volcano experiments.

Landslide susceptibility assessment in the rocky coast subsystem of Essaouira, Morocco

Abstract. In recent decades, multiple researchers have produced landslide susceptibility maps using different techniques and models, including the information value method, which is a statistical model that is widely applied to various coastal environments. This study aimed to evaluate susceptibility to landslides in the Essaouira coastal area using bivariate statistical methods. In this study, 588 distinct landslides were identified, inventoried, and mapped. Landslides are performed by means of observation and interpretation of different data sources, namely high-resolution satellite images, aerial photographs, topographic maps, and extensive field surveys. The rocky coastal system of Essaouira is located in the middle of the Atlantic coast of Morocco. The study area was split into 1534 cliff terrain units that were 50 m in width. For training and validation purposes, the landslide inventory was divided into two independent groups: 70 % for training and 30 % for validation. Twenty-two layers of landslide conditioning factors were prepared – namely, elevation, slope angle, slope aspect, plan curvature, profile curvature, cliff height, topographic wetness index, topographic position index, slope over area ratio, solar radiation, presence of faulting, lithological units, toe lithology, presence and type of cliff toe protection, layer tilt, rainfall, streams, land-use patterns, normalised difference vegetation index, lithological material grain size, and presence of springs. The statistical relationship between the conditioning factors and the different landslide types was calculated using the bivariate information value method in a pixel-based model and in the elementary terrain units-based model. Coastal landside susceptibility maps were validated using landslide training group partitions. The receiver operating characteristic curve and area under the curve were used to assess the accuracy and prediction capacity of the different coastal landslide susceptibility models. Two methodologies, considering a pixel-based approach and using coastal terrain units, were adopted to evaluate coastal landslide susceptibility. The results allowed for the classification of 38 % of the rocky coast subsystem as having high susceptibility to landslides, which were mostly located in the southern part of the Essaouira coastal area. These susceptibility maps will be useful for future planned development activities as well as for environmental protection.

UAV Photogrammetry and LiDAR Based Dataset of Spartina anglica Distribution and High-resolution Topographic Map in Ganghwado

The <i>Spartina anglica</i> in the tidal flat at the southern part of Ganghwado, it is known that the distribution area has gradually expanded since it was officially announced as invasive alien species in 2015. The government and local governments are continuing their efforts to remove the S. anglica, and for this, continuous distribution change monitoring is required. This study extracted the data of distribution and extent area of S. anglica from Zenmuse P1 sensor, and generated the high-resolution Digital Elevation Model (DEM) from Zenmuse L1 sensor. Optical and Lidar images were photographed at an altitude of 70 m, and Ground Sampling Distance (GSD) of optical images was obtained at 0.9 cm and GSD of lidar images at 5 cm spatial resolution. However, the data are resampled and provided in GSD 25 cm to comply with the "National Spatial Information Security Management Regulations of the Ministry of Land, Infrastructure and Transport" and "Security Business Regulations of the National Intelligence Service".

A model for simulating emergent patterns of cities and roads on real-world landscapes

Emergence of cities and road networks have characterised human activity and movement over millennia. However, this anthropogenic infrastructure does not develop in isolation, but is deeply embedded in the natural landscape, which strongly influences the resultant spatial patterns. Nevertheless, the precise impact that landscape has on the location, size and connectivity of cities is a long-standing, unresolved problem. To address this issue, we incorporate high-resolution topographic maps into a Turing-like pattern forming system, in which local reinforcement rules result in co-evolving centres of population and transport networks. Using Italy as a case study, we show that the model constrained solely by topography results in an emergent spatial pattern that is consistent with Zipf’s Law and comparable to the census data. Thus, we infer the natural landscape may play a dominant role in establishing the baseline macro-scale population pattern, that is then modified by higher-level historical, socio-economic or cultural factors.

Simulation and Design of Circular Scanning Airborne Geiger Mode Lidar for High-Resolution Topographic Mapping

Over the last two decades, Geiger-mode lidar (GML) systems have been developing rapidly in defense and commercial applications, demonstrating high point density and great collection efficiency. We presented a circular scanning GML system simulation model for performance prediction and developed a GML system for civilian mapping. The lidar system used an eye-safe fiber laser at 1545 nm coupled with a 64 × 64 pixels photon-counting detector array. A real-time data compression algorithm was implanted to reduce half of the data transmission rate and storage space compared to the uncompressing situation. The GML system can operate at aircraft above-ground levels (AGLs) between 0.35 km and 3 km, and at speeds in excess of 220 km/h. The initial flight tests indicate that the GML system can operate day and night with an area coverage of 366 km2/h. The standard deviations of the relative altimetric accuracy and the relative planimetric accuracy are 0.131 m and 0.152 m, respectively. The findings presented in this article guide the implementation of designing an airborne GML system and the data compression method.

TanDEM-X-based Ganghwa Tidal Flat High-resolution Topographic Map Construction and Service

This study extracted the data of Digital Elevation Model (DEM), tidal channel, and tidal channel density, slope based on TanDEM-X satellite of Ganghwa tidal flat. Monitoring and analysis of the decrease in the area of tidal flats in Korea are of great importance, and by judging the efficiency and accuracy in time and space, satellite data were obtained according to the analysis topic of the tidal flats. Since the west coast occupies a large proportion of domestic tidal flats, Ganghwa-do tidal flats were designated as the scope of the study. The produced materials are provided in the form of GEOTIFF(.tif) or Shape(.shp) files. To utilize the tidal flat data constructed in this way, it can be downloaded from the Environmental Big Data website (www.bigdata-environment.kr), an environmental business big data platform.

Comprehensive Analysis of UAV Flight Parameters for High Resolution Topographic Mapping

Unmanned Aerial Vehicles (UAVs) are aircrafts without pilot on board, which are controlled by the ground station or transmitter. The ability of UAVs to provide high-resolution imageries and accurate positioning makes it the best platform as compared to satellite images. Therefore, UAVs can speed up the topographic works, especially during data collection. Topographic mapping has been used by many agencies such as the government, private, and military. Furthermore, the geotagged high resolution UAV images can provide accurate results using Ground Control Points (GCPs). UAV flight parameters, such as flight altitude and overlap and sidelap percentages, can affect the topographic map result derived from the UAV images. The optimal flight altitude and overlap and sidelap percentages based on the specific topographic surface need to be investigated to produce an accurate topographic map. The aim of this study is to assess the accuracy of topographic maps from different flight parameters. There are two objectives to achieve the aim; i.e., to produce photogrammetric products from different overlaps and sidelaps as well as analyze the photogrammetric products with ground survey data. The selected flight altitude in this study is 60 m. However, the overlap percentages are 70%, 80%, and 90% and the sidelap percentages are 50%, 60%, and 70%. GCPs and Check Points (CPs) will be established using global navigation satellite system (GNSS) techniques, where the global positioning system (GPS) receiver is capable of real-time kinematic (RTK) to receive real-time data correction from the continuously operating reference stations (CORS) in different locations. This study will analyze the topographic results at different overlap and sidelap percentages using Root Mean Square Error (RMSE). The expected outcome of this study includes the comparison coordinates between CP coordinates and ground survey data coordinates, different digital terrain models (DTM), and different topographic maps.

Topography of the Aleutian Trench south-east off Bowers Ridge, Bering Sea, in the context of the geological development of North Pacific Ocean

The research is focused on the topographic modelling and mapping of the Aleutian Trench. The study area is situated in the Bering Sea, a marginal sea located northernmost of the Pacific Ocean, between Alaska and Kamchatka Peninsula. The geological setting of the region is characterized by the subduction of the oceanic Pacific Plate below the continental North American Plate. Other features include high seismic activity along the Aleutian island arcs bordering the oceanic seafloor. The objective of this paper is to explore the interaction between the geophysical setting affecting the relief of the seafloor by using geoinformation techniques and geological analysis. In the hypothesis of this study, variations in the geophysical fields as independent variables are reflected in the morphology of the seafloor, which can be observed using data visualization by the advanced cartographic scripting solutions. The open source high-resolution topographic map (ETOPO1), marine free-air gravity and Bouguer gravity anomaly data were used and integrated to investigate the potential correlation between the geophysical, geological, tectonic and topographic settings of the Bering Sea. Our main method includes bathymetric mapping of the area with publicly available bathymetric data using GMT. Materials include open source data: ETOPO1 raster grid with 1 arc-minute resolution, EGM96 gravity and vector contour layers of GMT. The research included complex thematic mapping of the region, including topographic, contour, geodetic and geophysical mapping, 3D modelling and geomorphological plotting of the 30 cross-section segments of the trench located SE off the Bowers Ridge. According to the processed ETOPO1 dataset, the minimal depth is -8480 m and the mean is -3089.154 m. The geoid undulations model shows that the majority of the gravity values lie in the interval between -10 and 20 m with the lowest values along the trench. The statistical histogram shows that the most common depth value in the segment of the Aleutian Trench is -4800 m, occurring 1722 times. The profile linear trend modelling was done with four different approaches of the regression model (y = f(x) + e) by weighted least squares (WLS) with arguments: 1) m2t = a + bt (polynomial model degree one); 2) m3t = a + bt + ct2 (polynomial model degree two); 3) m4t = a + bt + ct2 + dcos2π*t + esin2π*t (polynomial model with Fourier series one); and 4) additional plotting residuals. Surface modelling was performed using xyz modelling from the ASCII data enlarging fragment towards SE of the Bowers Ridge. The tested functionality of modules of GMT presented an effective cartographic scripting toolset enabling a precise topographic mapping and 3D modelling. The paper contributes to a more detailed understanding of the Pacific Ocean seafloor bathymetry, more specifically of the selected segment of the Aleutian Trench near Bowers Ridge area.

Prediction accuracy of reservoir break flood simulation model using finite volume method and UAV

Methods for producing high-resolution digital topographic maps using an unmanned aerial vehicle (UAV), and 3D fluid dynamics simulation to estimate the flooded areas caused by a collapsed reservoir, were proposed in this paper. The UAV flight path for photographing damaged areas was divided into two sections considering the drone flight time and overlapping range of the images in the x- and y-directions. The metadata taken by the drone were transferred into world coordinates by tracking the key features of the photographs of nearby areas using a 3D rotation matrix. The point cloud data with a 3D space were extracted from the registered images, and a digital surface map (DSM) was produced using a point cloud classification geometric mapping technique. To amend the serious elevation errors caused by natural or artificial obstacles, a kriging interpolation method was used to reproduce the DSM. A transient computational simulation that considers both the complex geometric topology and hydrodynamic energy of flowing water was conducted using FLOW-3D software to deal with an renormalization group (RNG) turbulence model. The flooded areas calculated through visual reading using images taken by the UAV were compared with the 3D simulation results for verification. The flooded areas estimated through the simulation were approximately 18.3% larger than those found by visual reading. Turbulent flows were mainly observed in obstacles or curved areas of the stream, and the differences in the water depth could be further increased. However, the villagers confirmed that the flooded areas were much greater than what was seen through the visual reading. Therefore, the combination of UAV surveying and the 3D simulation method based on the RNG turbulence model is recommended to accurately estimate flooded areas, and it will support an administrative policy aimed at minimizing the economic costs of damage caused by future reservoir collapses. Keywords: reservoir failure, flooded area, finite volume method, unmanned aerial vehicle, photogrammetric survey, digital surface model DOI: 10.25165/j.ijabe.20201306.4909 Citation: Jeon J, Choi W. Prediction accuracy of reservoir break flood simulation model using finite volume method and UAV. Int J Agric & Biol Eng, 2020; 13(6): 7–15.

High-resolution mapping of floodplain topography from space: A case study in the Amazon

Terrain elevation is essential for land management, navigation, and earth science applications. Remote sensing advancements have led to an increase in the availability of a range of digital elevation models with global to quasi-global land coverage. However, the generation of these models in water bodies requires specialized approaches, such as the delimitation of the shorelines (isobaths) of lakes over time. Therefore, the processing costs are high in complex areas with many lakes. Currently, there is no systematic topographic mapping of lakes and channels in large and complex floodplains using remote sensing data. We present here the first high-resolution topographic mapping (30 m) of the non-forested portion of the middle-lower Amazon floodplain using a new method based on in-situ Amazon river water levels and a flood-frequency map derived from the Landsat Global Surface Water Dataset. Validation using locally derived bathymetry showed a root mean square error (RMSE) of 0.89 m for floodplain elevation and a good representation of spatial patterns with Pearson's correlation coefficient of 0.77. Our approach for improving topographic representation in open water areas is an alternative to SRTM3 DEM or MERIT DEM, which represents these areas as a flat surface. We also generated the Amazon River bathymetry using nautical charts from the Brazilian Navy (average RMSE of 7.5 m and bias of 5 m), and floodplain depths maps corresponding to the high- and low-water periods of the river flood wave. The results show that the storage volume in the open-water floodplain varies 104.3 km3 on average each year (from 11.9 km3 in low-water to 116.2 km3 in high-water). The method can be applied to any temporarily flooded area to provide the often missing underwater digital topographic data required for hydrological, ecological, and geomorphological studies. The data set developed in this study can be found at https://doi.org/10.17632/vn599y9szb.1.

CorPhU: an algorithm based on phase closure for the correction of unwrapping errors in SAR interferometry

SUMMARY Interferometric Synthetic Aperture Radar (InSAR) is commonly used in Earth Sciences to study surface displacements or construct high resolution topographic maps. Recent satellites such as those of the Sentinel-1 constellation allow to derive dense deformation maps with millimetric precision with high revisit frequency. However, InSAR is still limited by interferometric coherence. Interferometric phase noise resulting from a loss of coherence, due to changes in scattering properties between repeated SAR acquisitions, may lead to unwrapping errors, which then in turn lead to centimetric errors in time-series reconstruction. We present an algorithm based on interferometric phase closure to automatically correct unwrapping errors. We describe the algorithm and highlight its performances with two case studies, in Lebanon with Envisat satellite data and in Central Turkey with Sentinel-1 data. The first data set is particularly affected by unwrapping errors because of long spatial (500 m) and temporal baseline interferograms (6 yr) and decorrelation due, in particular, to vegetation. The second data set contains unwrapping errors because of temporal changes in the scattering properties of the ground. For these two examples, the algorithm allows the correction of almost all detectable unwrapping errors, without requiring visual inspection or manual deletions. Our algorithm is efficient especially on large data sets, such as with Sentinel-1 constellation, where interferometric phase is redundant and improves eventually the reconstruction of time-series.

Relationship between Growth Faults, Subsidence, and Land Loss: An Example from Cameron Parish, Southwestern Louisiana, USA

O'Leary, M. and Gottardi, R., 2020. Relationship between growth faults, subsidence, and land loss: An example from Cameron Parish, Southwestern Louisiana, USA. Journal of Coastal Research, 36(4), 812–827. Coconut Creek (Florida), ISSN 0749-0208.This study investigates the relationship between faulting, subsidence, and land loss in coastal Louisiana. A methodology that integrates three-dimensional (3D) seismic data, well logs, high-resolution topographic mapping (LIDAR), and historical aerial photography is successfully developed to identify fault-related geomorphic changes in southwestern Louisiana's Chenier Plain. Analysis of a 3D seismic survey and well logs reveals the presence of 10 normal faults that form an east-west graben in the middle of the study area. Well logs were used to further constrain the geometry of the faults. Shallow water well logs were used to map the faults at shallow depth, below the resolution of the seismic survey. Fault traces were extrapolated to the surface by maintaining constant dip and projected on LIDAR data. Elevation profiles derived from the LIDAR were conducted across the different faults, and results show that a distinct difference between the upthrown and downthrown sides of the faults occurs. Historical aerial photographs were used to investigate any change in geomorphology from 1953 to 2017 within the study area. Results reveal the occurrence of water bodies on the immediate downthrown sides of suspected fault traces. These findings suggest that faulting influences and focuses areas where subsidence is happening and subsequent land loss may occur, and detailed understanding of active shallow faulting in coastal areas can be used to identify regions that are at risk of land loss.

Landslide Susceptibility Evaluation and Management Using Different Machine Learning Methods in The Gallicash River Watershed, Iran

This analysis aims to generate landslide susceptibility maps (LSMs) using various machine learning methods, namely random forest (RF), alternative decision tree (ADTree) and Fisher’s Linear Discriminant Function (FLDA). The results of the FLDA, RF and ADTree models were compared with regard to their applicability for creating an LSM of the Gallicash river watershed in the northern part of Iran close to the Caspian Sea. A landslide inventory map was created using GPS points obtained in a field analysis, high-resolution satellite images, topographic maps and historical records. A total of 249 landslide sites have been identified to date and were used in this study to model and validate the LSMs of the study region. Of the 249 landslide locations, 70% were used as training data and 30% for the validation of the resulting LSMs. Sixteen factors related to topographical, hydrological, soil type, geological and environmental conditions were used and a multi-collinearity test of the landslide conditioning factors (LCFs) was performed. Using the natural break method (NBM) in a geographic information system (GIS), the LSMs generated by the RF, FLDA, and ADTree models were categorized into five classes, namely very low, low, medium, high and very high landslide susceptibility (LS) zones. The very high susceptibility zones cover 15.37% (ADTree), 16.10% (FLDA) and 11.36% (RF) of the total catchment area. The results of the different models (FLDA, RF, and ADTree) were explained and compared using the area under receiver operating characteristics (AUROC) curve, seed cell area index (SCAI), efficiency and true skill statistic (TSS). The accuracy of models was calculated considering both the training and validation data. The results revealed that the AUROC success rates are 0.89 (ADTree), 0.92 (FLDA) and 0.97 (RF) and predication rates are 0.82 (ADTree), 0.79 (FLDA) and 0.98 (RF), which justifies the approach and indicates a reasonably good landslide prediction. The results of the SCAI, efficiency and TSS methods showed that all models have an excellent modeling capability. In a comparison of the models, the RF model outperforms the boosted regression tree (BRT) and ADTree models. The results of the landslide susceptibility modeling could be useful for land-use planning and decision-makers, for managing and controlling the current and future landslides, as well as for the protection of society and the ecosystem.