Raster Grid Research Articles

Okinawa Trough geophysical and topographic modeling by GDAL utilities and GRASS GIS

This paper presents using GDAL utilities and GRASS GIS for topographic analysis of the raster grids based on GEBCO DEM as NetCDF file at 15 arc-second intervals. The focus study area encompasses the area around Okinawa Trough, Ryukyu trench-arc system, southern Japan, East China Sea and the Philippine Sea, West Pacific Ocean. Several GDAL utilities were applied for data processing: gdaldem, gdalwarp, gdalinfo, gdal_translate. The data were imported to GRASS GIS via r.in.gdal. Data visualization highlighted high resolution and accuracy of GEBCO grid, enabling topographic modelling at the advanced level. The algorithm of DEM processing, implemented in GDAL utility gdaldem, was used for generating multi-purpose topographic models: aspect, hillshade, roughness and topographic indices, such as Topographic Position Index (TPI), Terrain Ruggedness Index (TRI). Thematic maps (topography, geoid, marine free-air gravity) were visualized using GRASS GIS modules for raster (d.rast, r.colors, r.contour) and vector (d.vect, v.in.region, d.legend) data processing. The results demonstrated smoother bathymetry in the East China Sea and rugged relief in the Philippine Sea which corresponds to their different geological and geophysical settings. The presented methodology of the topographic analysis based on DEM demonstrated technical aspects of GDAL and GRASS as scripting approach of advanced cartography.

GRASS GIS for topographic and geophysical mapping of the Peru-Chile Trench

The study area is located along the western continental margins of South America, Peru-Chile Trench south-east Pacific Ocean, geographically encompasses 90° to 60°W longitude and 55°S to 0° latitude. The study aims to perform a spatial analysis using GRASS GIS approach applied for processing and visualizing topographic and geophysical data on the study area. Data include following raster grids: topographic SRTM_15PLUS raster grid with 15 arc-second resolution, geoid model (EGM96), geophysical fields and gravity maps (marine free-air gravity and vertically corrected free-air gravity). The thematic grids were mapped by GRASS GIS modules and visualized for comparative analysis. Spatial analysis included plotting slope aspect, profile curvature, terrain elevation and modeled topographic classes based on the neighborhood analysis. The results include visualized geophysical and topographic maps of the study area showing correlation between the geophysical fields and topographic elevation. The variety of forms of the submarine relief of the Pacific Ocean seafloor was formed as a result of complex factors: tectonic movements, dislocations, active volcanism, geologic variations in rock density, which is reflected in visualized gravity and geoid maps. The actuality of the study is explained by high potential commercial interests in deep-water mineral resource deposits, oil and gas, which make ocean seafloor studies one of the most promising topics in geoscience. At the same time, the need for programming applications for big data analysis in geosciences requires testing advanced scripting approaches in cartography. Therefore, the current paper presents a multi-disciplinary approach combining geological analysis with technical cartographic aspects of data analysis and visualization.

Spatial distribution of cumulative impact on terrestrial ecosystem of the Fildes Peninsula, Antarctica

Antarctica, an area that is devoted to global peace and research, is being challenged by climate change, human activities, and pollution. There have been a number of studies concerning the state of the Antarctic ecological environment. However, a comprehensive and quantitative assessment of the impact of threats on the Antarctica ecological environment is still lacking. In this study, a cumulative impact assessment performed on the basis of expert judgement was used to estimate species-specific differences on the impact of seven threats: climate change, organic and nonorganic pollutants, station construction, power generation, oil spilling, and tourism. The terrestrial area of the Fildes Peninsula was divided into 103 cells using a raster grid of 0.25 km2, and cumulative impact assessment was applied to each cell. The analysis results indicated that cumulative impact scores (IC) ranged from 0 to 39.4, and the cumulative scores were divided into six categories ranging from very low impact (IC ≤ 7.08) to very high impact (IC > 20.54). More than half of the terrestrial area (57.3%) experienced “Very Low Impact” or “Low impact” scores. For single factors, climate change was identified as a rapidly growing and significant threat facing the terrestrial ecosystems of Antarctica. In addition, tourism had the greatest impact among all human activities. The analytical process and resulting map indicate that it is necessary to develop international policies on the restriction of tourist activity space and strength the organic pollutant controls for terrestrial ecosystem protection in the Fildes Peninsula, Antarctica.

GRASS GIS Modules for Topographic and Geophysical Analysis of the ETOPO1 DEM and Raster Data: North Fiji Basin, Pacific Ocean

The paper presents topographic analysis based on the raster data (NetCDF and grid formats) and visualization of the geophysical datasets that resembles the topographic surface. Geographically, the research focuses on the region of North Fiji Basin, South Pacific Ocean. North Fiji Basin is one of the marginal basins located at the converging boundary between the Pacific and Australian tectonic plates and is notable for complex geological settings. Methodology is based on GRASS GIS and includes scripting and cartographic visualization. Data include ETOPO1, GEBCO, EGM96 gravity and geoid raster grids imported to GRASS GIS via GDAL library (‘r.in.gdal’ module) from NetCDF and GRD formats, evaluated and visualized. Several GRASS modules were used as a sequential scripting for displaying and modelling data. Geomorphometric analysis (slopes, curvature, aspect, elevation) was performed by module ‘r.slope.aspect’ based on ETOPO1 grid. Statistical data analysis (histograms, polar diagram) for topographic and geoid gravitational fields were visualized by combination of GRASS modules d.rast, g.region, d.polar, d.histogram, d.grid, d.legend, d.text. Topographic analysis reveal that free-air gravity anomaly mark the continental shelf-slope border showing that generally, geophysical settings are dominated by the topographic effect. These observations are consistent with the inferred prominent role of the geophysical settings. The histograms reveal that topography (trenches, abyssal plains, shelf areas) has values between -5,000 and -1,000 m, and a clear peak with major values between 100 and 350 m above sea level. This distribution indicates that dominating depths of the ocean floor in North Fiji Basin are between -1,500 to -3,000 m. The aspect map of the ETOPO1 initial raw raster grid show that the surface has mostly 50°-110° oriented slope followed by data range in 250°-300° oriented slopes which is well correlating with submarine topography and general relief forms. The steepening of the gravity values between 50 and 55 mGal and 58 to 63 mGal indicates geoid undulations suggesting that bathymetry is controlled by the geological settings in the study area. Console- based scripts of GRASS GIS are presented together with cartographic outputs showing its effectiveness for the geographic spatial analysis.

Insights on the Indian Ocean Tectonics and Geophysics Supported by GMT.

This paper presented analyzed and summarized data on geological and geophysical settings about the tectonics and geological structure of the seafloor of the Indian Ocean by thematic visualization of the topographic, geophysical and geological data. The seafloor topography of the Indian Ocean is very complex which includes underwater hills, isolated mountains, underwater canyons, abyssal and accumulative plains, trenches. Complex geological settings explain seismic activity, repetitive earthquakes, and tsunami. Understanding and prognosis of the disastrous and catastrophic geological events is strongly based on correct data analysis, modelling and visualization. An important feature of this paper is mapping multi-source high-resolution data by GMT. Data include raster grids in NetCDF and GRD formats: ETOPO1, geologic and marine free-air gravity data, EGM96, age, spreading rates, and spreading asymmetry of the ocean crust by NOAA, total sediment thickness. Data were visualized by GMT modules to compare and analyze geophysical and geological settings of the Indian Ocean. Visualization reveled correlations between high bathymetric variations of the oceanic seafloor, distribution of main geological seafloor fabric: Southwest, Southeast, Mid and Carlsberg ridges. Tectonic maps were plotted to perform comparative analysis of several variables: crust age, spreading half rates (mm/yr), asymmetries in crustal accretion on conjugate ridge flanks (%), variations in the geopotential and gravimetric models. Being the warmest of the world’s ocean, Indian Ocean has specific climatic conditions (repetitive monsoons, tsunamis, cyclones and storms), complex geologic seafloor structure with triple junction and unique geographic settings. Presented paper contribut ed to the regional studies of the Indian Ocean.

Ecological Population Status of the Most Common Bird Species in Northern Altai Low-Mountain Forests and the Principal Difference in Avifauna Status in Altai and Baikal Regions

In 2016 and 2017, from April to July, bird individual nesting home ranges were regularly mapped along the permanent census route (2.8 km) in the low-mountain forests dominated by pine and birch. For each bird species, the nesting densities and average sizes of the bird individual nesting home range were estimated, and raster maps of spatial allocation (MSA) at the scale of the raster grid of 50 × 50 m were obtained. The degree of spatial conservatism (DSC) for each local population was inferred from the pairwise comparisons of the specific MSAs obtained at the same area (28 ha) in different years with the use of the Gamma rank correlation method. The statistical dependence of the population habitat area on DSC was demonstrated earlier (Cherenkov, 2017). The more habitat area is found within the trial plot, the less dependent (random) the individual spatial allocation within a population is observed in different years. Significant DSC estimates (p < 0.05) were obtained for 15 species, and their habitat areas and habitat saturation were found. The population status was inferred from the degree of habitat saturation. Average estimates of the degree of habitat saturation were close in migratory and nonmigratory species (49 and 45%, respectively). The Altai migratory birds wintering in Southeast Asia did not differ statistically in the degree of habitat saturation from those wintering in Southern Europe and North Africa. A comparison of avifauna status of the Altai and Baikal regions revealed substantial differences. In Altai the number of the most common migratory nesting species is almost twice as high, their average nesting density is four times higher, and habitat saturation is twice as high as in the birds of the Baikal region. The interregional differences in the degree of habitat saturation indicate that most of populations of the migratory species of the Baikal region are subject to twice as much intensive pressure of some factors limiting the population growth compared to the Altai populations. At the same time, there were no significant differences in the ecological population status of the nonmigratory species between these regions. Close estimates of the degree of habitat saturation in nonmigratory species in the Altai and Baikal regions support a suggestion that the integrate influence of factors limiting their population numbers is similar in both regions. Close estimates of the degree of habitat saturation and nesting density in the migratory and nonmigratory Altai species show that neither of the two strategies of surviving gives a pronounced advantage. The difference between the Altai and Baikal regions in the degree of habitat saturation in the migratory species is seemingly determined by the different mortality levels in the wintering areas and on the routes of migrations.

SEAFLOOR MAPPING OF THE ATLANTIC OCEAN BY GMT: VISUALIZING MID ATLANTIC RIDGE SPREADING, SEDIMENT DISTRIBUTION AND TECTONIC DEVELOPMENT

The study presents the insights of the tectonic development and geological settings of the Atlantic Ocean supported by cartographic visualization in Generic Mapping Tools (GMT). The aim is to study geologic situation and trends in the tectonic development of the Mid-Atlantic Ridge and Atlantic Ocean seafloor. The objective is to find out impact of various factors (such as volcanic, tectonic, hydrothermal and sedimentary processes) that sculpt seafloor geomorphology, and correlation between early history of crust formation, geological processes and present submarine landforms. Other assignments in this work refer to mutual comparison of raster grids on sedimentation, topography, geology, seafloor fabric and highlighting similarities among the landforms and sediment thickness. Asymmetry in crustal accretion is explained by the tectonic history of the lithosphere formation. Correlation between plate subduction and development of the submarine landforms is explained by the Earth's crust extension resulting in formation of cracks, elongations, faults, rifts. Ocean seafloor geomorphology is shaped by a variety of factors that impact its form at different scales. These drivers (tectonic evolution, oceanic currents, hydrology, sedimentation) have effects on geomorphic landforms of the seafloor in context of historic geological development and during Quaternary. Technical part of this work was performed by GMT scripting toolset with all maps plotted in American polyconic projection. The results are received by overlay, cartographic analysis and synthesis of the multi-source geodata through mapping and interpreting grids (ETOPO1, EGM96, GlobSed, crustal age). This work contributes to expand the knowledge on geological and tectonic development of the Atlantic Ocean seabed in order to complete the view of its submarine geomorphology

Fractal surfaces of synthetical DEM generated by GRASS GIS module r.surf.fractal from ETOPO1 raster grid

The research problem is about to generate artificial fractal landscape surfaces from the Digital Elevation Model (DEM) using a stochastic algorithm by Geographic Resources Analysis Support System Geographic Information System (GRASS GIS) software. Fractal surfaces resemble appearance of natural topographic terrain and its structure using random surface modelling. Study area covers Kuril-Kamchatka region, Sea of Okhotsk, North Pacific Ocean. Techniques were included into GRASS GIS modules (r.relief, d.rast, r.slope.aspect, r.mapcalc) for raster calculation, processing and visualization. Module 'r.surf.fractal' was applied for generating synthetic fractal surface from ETOPO1 DEM GeoTIFF using algorithm of fractal analysis. Three tested dimensions of the fractal surfaces were automatically mapped and visualized. Algorithm of the automated fractal DEM modelling visualized variations in steepness and aspect of the artificially generated slopes in the mountains. Controllable topographic variation of the fractal surfaces was applied for three dimensions: dim=2.0001, 2.0050, 2.0100. Auxiliary modules were used for the visualization of DEMs (d.rast, r.colors, d.vect, r.contour, d.redraw, d.mon). Modules 'r.surf.gauss' and 'r.surf.random' were applied for artificial modelling as Gauss and random based mathematical surfaces, respectively. Univariate statistics for fractal surfaces were computed for comparative analysis of maps representing continuous fields by module 'r.univar': number of cells, min/max, range, mean, variance, standard deviation, variation coefficient and sum. The paper includes 9 maps and GRASS GIS codes used for visualization.

Base-Hurricane: A new extension for the Landis-II forest landscape model

Hurricanes in the southeast United States are infrequent disturbances that affect large areas and have a large effect on forest succession. In order to understand and quantify this effect, we added a new module to the LANDIS-II landscape change model. Focusing on the southeast coast of the United States, we simulated stochastic hurricanes for 50 years. For each simulated storm, the new model extension generates the maximum sustained wind speed over the region and uses the resulting parameter surface to compute maximum sustained wind speed for each cohort cell in a raster grid. Mortality is estimated for each species and age cohort in each cell based on the maximum sustained wind speed, altering forest succession. Results indicate that hurricanes reduce average aboveground biomass by > 20% over 50 years on a landscape in Fort Bragg, North Carolina (USA) compared to a scenario without hurricanes and increased uncertainty of projected succession.

Presence-only and Presence-absence Data for Comparing Species Distribution Modeling Methods

Species distribution models (SDMs) are widely used to predict and study distributions of species. Many different modeling methods and associated algorithms are used and continue to emerge. It is important to understand how different approaches perform, particularly when applied to species occurrence records that were not gathered in struc­tured surveys (e.g. opportunistic records). This need motivated a large-scale, collaborative effort, published in 2006, that aimed to create objective comparisons of algorithm performance. As a benchmark, and to facilitate future comparisons of approaches, here we publish that dataset: point location records for 226 anonymized species from six regions of the world, with accompanying predictor variables in raster (grid) and point formats. A particularly interesting characteristic of this dataset is that independent presence-absence survey data are available for evaluation alongside the presence-only species occurrence data intended for modeling. The dataset is available on Open Science Framework and as an R package and can be used as a benchmark for modeling approaches and for testing new ways to evaluate the accuracy of SDMs.

Reconstruction of the far field radiated by an offset mounted volumetric AUT from non‐redundant spherical spiral near‐field measurements

This work provides an experimental assessment of the near to far-field transformation (NTFFT) with spherical spiral scan, which properly accounts for the mounting of a volumetric AUT in offset configuration. Such a NTFFT, based on the nonredundant sampling representations of electromagnetic fields using a spherical modelling of the antenna under test (AUT), requires the same number of near-field (NF) spiral data when the AUT is mounted both in onset and offset configuration, because this number depends only on the area of the modelling sphere. The reported experimental results prove the effectiveness of the developed NTFFT and of the related two-dimensional optimal sampling interpolation scheme used to reconstruct, from the spiral NF samples, the NF data at the raster grid points required by the classical spherical NTFFT.

Electricity generation and demand flexibility in wastewater treatment plants: Benefits for 100% renewable electricity grids

In future, the low carbon electricity grid will need an additional potential of energetic flexibility to compensate the variable renewable supply. Wastewater treatment plants have the potential to provide electricity demand and generation flexibility. A novel approach of utilising the energetic flexibility in wastewater treatment plants to optimize the installed capacity of a fully renewable electricity grid in Australia is presented. In this hourly electricity supply simulation, both the electricity generation and demand of wastewater treatment plants are shifted for reducing the required size of 100% renewable electricity grid and achieving perfect supply-demand matching. The electricity demand and dispatchable electricity generation capacity of cogeneration systems in wastewater treatment plants are modelled on a 90×110 raster grid. For a 6-hour shift in wastewater treatment plant’s electricity demand and it’s electricity generation limited to five times the current capacity, a 100% renewable electricity grid would need an installed capacity of around 149 GW to meet the existing reliability standard (6–8 h of power outages per year). The electricity generation cost is around 16 ¢/kWh with a capacity factor of 28% and spilt electricity of less than 21%. The electricity generated from sewage methane in wastewater treatment plants is only 1% of the total generation and is utilised along with biomass power plants to plug demand-supply gaps. Our results indicate that a 2% reduction in installed capacity and 11% reduction in levelized cost of electricity is achieved by utilizing the energetic flexibility of wastewater treatment plants.

GMT Based Comparative Geomorphological Analysis of the Vityaz and Vanuatu Trenches, Fiji Basin

The study is geographically focused on the two deep-sea trenches: Vanuatu and Vityaz, Fiji Basin, East Australia, located in the area of the double convergent complex boundary of Pacific and Indo-Australian plates in the North Fiji back-arc basin. Complex geophysical settings results in the formation of the trenches, seismicity, geodynamic complexity and instability of the region. The work aimed at modelling and comparative statistical analysis of the bathymetry and geomorphology of two trenches. Technically, the methodology of this work is based on the Generic Mapping Tools (GMT) using cartographic mapping of the geophysical, tectonic and geological settings, 2D and 3D modelling, visualizing raster grids GEBCO, ETOPO1, ETOPO5. Histogram topographic equalization (equalized, normalized, quadratic) was done using module ’grdhisteq’. Modelling geoid and gravity was based on EGM96 by sequence of GMT modules. The cross-spectrals of 2D binary raster grids were compared and their coherency plotted by ’grdfft’. The automated cross-sectioning was done using ’grdtrack’ module. The results include modelled transects visualizing trenches asymmetry, bathymetric and geomorphic variations. Vityaz Trench is shallower with depths <–6,100 m, has ’bell-shape’ data distribution with two peaks at ranges –3,500 m to –3,700 m, and –4,800 m to –5,000 m. Vanuatu Trench reaches up to –7,000 m with majority of values between –5,000 m to –3,000 m, even data distribution with depth increasing at –2,200 m to –800 m. Geomorphic form of both trenches varies: Vityaz has flat wide bottom similar to a trough, steeper gradient eastern slope. Vanuatu has V-form classic shape with gentle shapes on both slopes. Selected segment of Vityaz has shallower depths with maximal <–5,000 m while Vanuatu is deeper (–6,000 m). Cartographic functionality of the GMT is presented by various cartographic projections: Mercator, Behrman, Cylindrical Stereographic, Hammer retroazimuthal. 3D modelling was done using GMT module ’grdview’. Trenches were visualized and rotated at 160°/45°azimuth. Presented maps, 2D and 3D models and graphics are plotted and visualized by GMT with selected code snippets explained. Current work contributes to the methods of the modelling of deep-sea trenches geomorphology.

МОРФОЛОГИЯ КРОВЕНОСНОГО РУСЛА ЛЕГКИХ ОВЦЫ ПОРОДЫ ДОРПЕР НА ЭТАПАХ ПОСТНАТАЛЬНОГО ОНТОГЕНЕЗА

Sheep farming is one of the main branch of animal husbandry, which is of great national economic importance. For the study at the department of animal anatomy of St. Peters-burg state Academy of veterinary medicine was used cadaver material from animals, obtained during slaughter from the "Gzhelskoe Podvorye", Moscow region. For the study was used a complex anatomical technique, including thin anatomical dissec-tion, vasography and macrophotography. Intravascular injection was performed through the abdominal aorta. The contrasting mass for x-ray diagnostics was a suspension of lead meerkat in turpentine with rectified ethyl alcohol and glycerin. Then the material was fixed for 5 days in 10% formalin solu-tion. X-ray diagnostics of cadaver material was performed on a Gierthhf 200A Power x-ray machine with the following technical conditions: 40 kV, 0.42 mAs. Focal length 90 cm, raster grid was not used. All meas-urements and calculations were performed in the Canon electronic program. Based on our research, we found for the first time that the lungs of the studied animals receive blood from two different vascular systems. The first refers to the small circle of blood cir-culation and is represented by the pulmonary arteries. The second originates from the large circle of blood circulation and is repre-sented by the bronchial arteries. In this case, both systems take an unequal part in the nu-trition of the lungs. Thus, the bronchial arter-ies feed the structures of the bronchial tree, the parenchyma of the lungs, as well as their lymph nodes and pleura. We also found that the largest increase in the diameter of these vessels occurs in these animals from five to six months to one year.

Geophysical Modelling of the Middle America Trench using GMT

The study is focused on the geomorphological analysis of the Guatemala Trench, East Pacific Ocean. Research goal is to find geometric variations in western and eastern flanks of the trench and correlation of the submarine geomorphology with geologic settings and seismicity through numerical and graphical modelling. Methods include GMT based analysis of the bathymetry, geomorphic shape and surface trends in topography and gravity grids. Dataset contains raster grids on bathymetry, gravity, geoid and geological layers. Technical workflow is following: 1) Bathymetric mapping by modules ('grdcut', 'grdimage'); 2) Datasets visualizing and analysis, 3) Topographic and gravimetric surface modelling by ASCII data; 4) Cartographic mapping ('psbasemap', 'psxy', 'grdcontour') 4) 3D-mesh modelling; 5) Automatically digitized orthogonal cross-stacked profiles (‘grdtrack’); 6) Visualizing curvature trends (‘trend1d’); 7) statistical histograms. Results reveal unevenness in the structure of the submarine landforms. Modelling cross-section profiles highlighted depth variation at different parts of the transects and seafloor segments. Geomorphic structure has straight shape form of the slopes with steep oceanward forearc. Its geometry has steep and strait shape which correlates with seismicity. Depth samples vary: -3000 to -6200 m, seafloor is 3-5 km wide. Trench has symmetric accurate 'V- shaped' geometric form for the segment of -30 to -30 km. Oceanward side slope increases towards continental shelf, left flank stabilizes in depths at -50 km from the trench axis, deepens at -50 to 0 m, decreases at -3,200 to -5,800. Oceanward flank gradient varies: slope steepness of 35,63° at 0-20 km, 42,17° at 20-40 km, 44° at 40-60km. Left flank has 43,24° at 0-24 km, 28,33° at 24-40 km, 14° at 40-60 km, 1,13° at 60-200 km. Marine vertical gravity correlates with tectonic slab contours (20-30 mGal on the trench slopes). The study demonstrated effective GMT-based framework with a multi-disciplinary scope that combined cartographic methods of modelling deep-sea trench profiles with geological, bathymetric and geophysical analysis. Technical application of the advanced cartographic solutions and high quality mapping by GMT demonstrated its functionality for data analysis and effectiveness of the geoinformation processing. Proposed techniques and workflow methodology provided framework for geological mapping and can be applied in further similar research.

Twice optimised near‐field scanning system for antenna characterisation

The near-field (NF) acquisition time depends on the sampling strategy and on the measurement hardware. Optimised sampling based on singular value optimisation dramatically reduces the number of measurement points and the scanning path length compared to conventional samplings, without impairing the far-field reconstruction. Furthermore, an optimised control approach, tracking a sufficiently smooth trajectory allows better performance in terms of velocity and precision, significantly reducing the scanning time. We show that the combined use of an optimised sampling and an optimised controller drastically reduces the measurement time. The sampling strategy provides a raster grid of optimally selected rows hosting samples optimally arranged according to a row-wise non-uniform distribution. The optimised control drives the NF scanner and the vector network analyser to acquire the data along each row by a continuous probe movement with a variable velocity, accelerating and decelerating between two consecutive sampling points. The sparsity of the NF locations enables a significant increase in the average speed between two consecutive points. The controller is realised with a proportional-integral-derivative law with a compensation signal and a filter downstream. The controller does not demand complex hardware and can be realised in an extremely simple, cheap and off-the-shelf solution.

Topographic surface modelling using raster grid datasets by GMT: example of the Kuril–Kamchatka Trench, Pacific Ocean

Abstract The study area is focused on the Kuril–Kamchatka Trench, North Pacific Ocean. This region is geologically complex, notable for the lithosphere activity, tectonic plates subduction and active volcanism. The submarine geomorphology is complicated through terraces, slopes, seamounts and erosional processes. Understanding geomorphic features of such a region requires precise modelling and effective visualization of the high-resolution data sets. Therefore, current research presents a Generic Mapping Tools (GMT) based algorithm proposing a solution for effective data processing and precise mapping: iterative module-based scripting for the automated digitizing and modelling. Methodology consists of the following steps: topographic mapping of the raster grids, marine gravity and geoid; semi-automatic digitizing of the orthogonal cross-section profiles; modelling geomorphic trends of the gradient slopes; computing raster surfaces from the xyz data sets by modules nearneighbor and XYZ2grd. Several types of the cartographic projections were used: oblique Mercator, Mercator cylindrical, conic equal-area Albers, conic equidistant. The cross-section geomorphic profiles in a perpendicular direction across the two selected segments of the trench were automatically digitized. Developed algorithm of the semi-automated digitizing of the profiles enabled to visualize gradients of the slope steepness of the trench. The data were then modelled to show gradient variations in its two segments. The results of the comparative geomorphic analysis of northern and southern transects revealed variations in different parts of the trench. Presented research provided more quantitative insights into the structure and settings of the submarine landforms of the hadal trench that still remains a question for the marine geology. The research demonstrated the effectiveness of the GMT: a variety of modules, approaches and tools that can be used to produce high-quality mapping and graphics. The GMT listings are provided for repeatability.

Parallelizing Multiple Flow Accumulation Algorithm using CUDA and OpenACC

Watershed analysis, as a fundamental component of digital terrain analysis, is based on the Digital Elevation Model (DEM), which is a grid (raster) model of the Earth surface and topography. Watershed analysis consists of computationally and data intensive computing algorithms that need to be implemented by leveraging parallel and high-performance computing methods and techniques. In this paper, the Multiple Flow Direction (MFD) algorithm for watershed analysis is implemented and evaluated on multi-core Central Processing Units (CPU) and many-core Graphics Processing Units (GPU), which provides significant improvements in performance and energy usage. The implementation is based on NVIDIA CUDA (Compute Unified Device Architecture) implementation for GPU, as well as on OpenACC (Open ACCelerators), a parallel programming model, and a standard for parallel computing. Both phases of the MFD algorithm (i) iterative DEM preprocessing and (ii) iterative MFD algorithm, are parallelized and run over multi-core CPU and GPU. The evaluation of the proposed solutions is performed with respect to the execution time, energy consumption, and programming effort for algorithm parallelization for different sizes of input data. An experimental evaluation has shown not only the advantage of using OpenACC programming over CUDA programming in implementing the watershed analysis on a GPU in terms of performance, energy consumption, and programming effort, but also significant benefits in implementing it on the multi-core CPU.

Improved Fast Adaptive IDW Interpolation Algorithm based on the Borehole Data Sample Characteristic and Its Application

The inverse distance weighted algorithm (IDW) is one of the most widely used algorithms in geoscience calculation based on its university and simple theory. However, in the practical application based on borehole sampling data, the distance between boreholes is further than the sampling distance along the bedding direction of one borehole, and it needs to search all the near points through a large number of distance calculation, and the process is very slow, so this lacks practicality in the spatial interpolation of the large amount and non-uniform distribution data. Based on the special features of the borehole sampling data, this paper presents a fast adaptive and improved inverse distance weighted interpolation method. And firstly the sample point position could be indexed by the adaptive cube grid raster, then determine the index grid in the horizontal and vertical directions of the interpolation point, and combine these grids for the finally IDW calculation, which significantly improves the search speed of the adjacent interpolation calculation points. It can improve the engineering applicability of the IDW method, especially the three-dimensional spatial interpolation and computing has a good application prospect.

LANDSLIDES SUSCEPTIBILITY ZONATION OF THE TERRITORY OF NORTH MACEDONIA USING ANALYTICAL HIERARCHY PROCESS APPROACH

Landslides are natural disasters that have an impact in many areas around the world including the territory of the Republic of Macedonia. In this country, about 300 large landslides are registered, most of which cause serious damage to the infrastructure almost every year. In that sense, the mapping of sites that are susceptible to landslides is essential for the management of these areas. This is a crucial step to prevent landslides in places where this could be expected or to mini-mize its damages. Therefore, a heuristic approach of Analytical Hierarchy Process (AHP) combined with Geographic In-formation System (GIS) and Remote Sensing (RS) is used in this work for the assessment of potential landslide areas in the Republic of Macedonia. In the procedure, 6 triggering factors indicating a strong influence on the landslide activity are selected, including lithology, slope angle, land cover, terrain curvature, distance from rivers and distance from roads. Through the procedure, expert-based weight of these factors is made. The LS model is produced with the summing up of the factor layers in the form of harmonized raster grids. Finally, the values of the grid model are classified according to the quantiles and natural breaks scheme. The produced maps show acceptable results confirmed by validation methods and ROC analysis, indicating that about 40% of the country area is under high and very high landslide susceptibility. This ap-proach can be further improved if combined with statistical methods in the form of a hybrid model.