scholarly journals APPLICATION OF AHP METHOD FOR MAPPING SLOPE GEOMORPHIC PHENOMENA

2017 ◽  
Author(s):  
Florin Constantin MIHAI
Keyword(s):  
Risk Mitigation ◽  
Characteristic Curve ◽  
Confusion Matrix ◽  
Predictive Performance ◽  
Landslide Risk ◽  
Good Correspondence ◽  
Topographic Features ◽  
Digital Elevation ◽  
Elevation Model ◽  
Hierarchy Process

Landslides are common and frequent geomorphic phenomena for the plateau regions in Romania having important consequences, especially economic ones, that needs designing scientific and technical plans for landslide risk mitigation. For this, an important preliminary step is assessing and mapping the landslide susceptibility. This paper examines a plateau zone in eastern Romania providing such a map, based on the landslides inventory, the digital elevation model (DEM) and the thematic layers of several factors thought to be potential predictors of landslides occurrence: topographic features, land use, and lithology. The methodological framework is based on the analytical hierarchy process (AHP) principles and factors weights attributed based on frequency of landslides. The predictive performance of the model was assessed using the confusion matrix, the ROC (receiver operating characteristic) curve and the AUC (area under curve) parameter. The results indicate a good correspondence between the susceptibility estimated for the test samples and for the validation samples

scholarly journals InSAR Monitoring of Landslide Activity in Dominica

2021 ◽  
Vol 13 (4) ◽  
pp. 815
Author(s):  
Mary-Anne Fobert ◽  
Vern Singhroy ◽  
John G. Spray
Keyword(s):  
Risk Mitigation ◽  
Disaster Mitigation ◽  
Aerial Images ◽  
Landslide Inventory ◽  
Landslide Risk ◽  
Susceptibility Map ◽  
Interferometric Synthetic Aperture Radar ◽  
Rainfall Events ◽  
Susceptibility Maps ◽  
Digital Elevation

Dominica is a geologically young, volcanic island in the eastern Caribbean. Due to its rugged terrain, substantial rainfall, and distinct soil characteristics, it is highly vulnerable to landslides. The dominant triggers of these landslides are hurricanes, tropical storms, and heavy prolonged rainfall events. These events frequently lead to loss of life and the need for a growing portion of the island’s annual budget to cover the considerable cost of reconstruction and recovery. For disaster risk mitigation and landslide risk assessment, landslide inventory and susceptibility maps are essential. Landslide inventory maps record existing landslides and include details on their type, location, spatial extent, and time of occurrence. These data are integrated (when possible) with the landslide trigger and pre-failure slope conditions to generate or validate a susceptibility map. The susceptibility map is used to identify the level of potential landslide risk (low, moderate, or high). In Dominica, these maps are produced using optical satellite and aerial images, digital elevation models, and historic landslide inventory data. This study illustrates the benefits of using satellite Interferometric Synthetic Aperture Radar (InSAR) to refine these maps. Our study shows that when using continuous high-resolution InSAR data, active slopes can be identified and monitored. This information can be used to highlight areas most at risk (for use in validating and updating the susceptibility map), and can constrain the time of occurrence of when the landslide was initiated (for use in landslide inventory mapping). Our study shows that InSAR can be used to assist in the investigation of pre-failure slope conditions. For instance, our initial findings suggest there is more land motion prior to failure on clay soils with gentler slopes than on those with steeper slopes. A greater understanding of pre-failure slope conditions will support the generation of a more dependable susceptibility map. Our study also discusses the integration of InSAR deformation-rate maps and time-series analysis with rainfall data in support of the development of rainfall thresholds for different terrains. The information provided by InSAR can enhance inventory and susceptibility mapping, which will better assist with the island’s current disaster mitigation and resiliency efforts.

scholarly journals Effect of DEM Interpolation Neighbourhood on Terrain Factors

2019 ◽  
Vol 8 (1) ◽  
pp. 30 ◽  
Author(s):  
Ying Zhu ◽  
Xuejun Liu ◽  
Jing Zhao ◽  
Jianjun Cao ◽  
Xiaolei Wang ◽  
...  
Keyword(s):  
Interpolation Method ◽  
Simulated Data ◽  
Topographic Features ◽  
Structure And Morphology ◽  
Digital Elevation ◽  
Different Types ◽  
Slope Error ◽  
Elevation Model ◽  
The Impact ◽  
Mls Method

Topographic factors such as slope and aspect are essential parameters in depicting the structure and morphology of a terrain surface. We study the effect of the number of points in the neighbourhood of a digital elevation model (DEM) interpolation method on mean slope, mean aspect, and RMSEs of slope and aspect from the interpolated DEM. As the moving least squares (MLS) method can maintain the inherent properties and other characteristics of a surface, this method is chosen for DEM interpolation. Three areas containing different types of topographic features are selected for study. Simulated data from a Gauss surface is also used for comparison. First, the impact of the number of points on the DEM root mean square error (RMSE) is analysed. The DEM RMSE in the three study areas decreases gradually with the number of points in the neighbourhood. In addition, the effect of the number of points in the neighbourhood on mean slope and mean aspect was studied across varying topographies through regression analysis. The two variables respond differently to changes in terrain. However, the RMSEs of the slope and aspect in all study areas are logarithmically related to the number of points in the neighbourhood and the values decrease uniformly as the number of points in the neighbourhood increases. With more points in the neighbourhood, the RMSEs of the slope and aspect are not sensitive to topography differences and the same trends are observed for the three studied quantities. Results for the Gauss surface are similar. Finally, this study analyses the spatial distribution of slope and aspect errors. The slope error is concentrated in ridges, valleys, steep-slope areas, and ditch edges while the aspect error is concentrated in ridges, valleys, and flat regions. With more points in the neighbourhood, the number of grid cells in which the slope error is greater than 15° is gradually reduced. With similar terrain types and data sources, if the calculation efficiency is not a concern, sufficient points in the spatial autocorrelation range should be analysed in the neighbourhood to maximize the accuracy of the slope and aspect. However, selecting between 10 and 12 points in the neighbourhood is economical.

scholarly journals LANDSLIDE SUSCEPTIBILITY MODELLING IN SELECTED STATES ACROSS SE. NIGERIA

2020 ◽  
Vol 4 (1) ◽  
pp. 23-27
Author(s):  
R. O. E. Ulakpa ◽  
V.U.D. Okwu ◽  
K. E. Chukwu ◽  
M. O. Eyankware
Keyword(s):  
Landslide Susceptibility ◽  
Landsat Imagery ◽  
Control Measures ◽  
Landslide Risk ◽  
Susceptibility Map ◽  
Landsat 8 ◽  
Aerial Photos ◽  
Anambra State ◽  
Digital Elevation ◽  
Elevation Model

Identification and mapping of landslide is essential for landslide risk and hazard assessment. This paper gives information on the uses of landsat imagery for mapping landslide areas ranging in size from safe area to highly prone areas. Landslide mitigation largely depends on the understanding of the nature of the factors namely: slope, soil type, lineament, lineament density, elevation, rainfall and vegetation. These factors have direct bearing on the occurrence of landslide. Identification of these factors is of paramount importance in setting out appropriate and strategic landslides control measures. Images for this study was downloaded by using remote sensing with landsat 8 ETM and aerial photos using ArcGIS 10.7 and Surfer 8 software, while Digital Elevation Model (DEM) and Google EarthPro TM were used to produce slope, drainage, lineament and elevation. From the processed landsat 8 imagery, landslide susceptibility map was produced, and landslide was category into various class; low, medium and high. From the study, it was observed that Enugu and Anambra state ranges from high to medium in terms of landslide susceptibility, Imo state ranges from medium to low.

scholarly journals Automatic landslide length and width estimation based on the geometric processing of the bounding box and the geomorphometric analysis of DEMs

2016 ◽  
Vol 16 (8) ◽  
pp. 2021-2030 ◽  
Author(s):  
Mihai Niculiţǎ
Keyword(s):  
Characteristic Curve ◽  
Routing Algorithm ◽  
Bank Failures ◽  
Bounding Box ◽  
Digital Elevation ◽  
Elevation Difference ◽  
The Difference ◽  
Bounding Boxes ◽  
Elevation Model

Abstract. The morphology of landslides is influenced by the slide/flow of the material downslope. Usually, the distance of the movement of the material is greater than the width of the displaced material (especially for flows, but also the majority of slides); the resulting landslides have a greater length than width. In some specific geomorphologic environments (monoclinic regions, with cuesta landforms type) or as is the case for some types of landslides (translational slides, bank failures, complex landslides), for the majority of landslides, the distance of the movement of the displaced material can be smaller than its width; thus the landslides have a smaller length than width. When working with landslide inventories containing both types of landslides presented above, the analysis of the length and width of the landslides computed using usual geographic information system techniques (like bounding boxes) can be flawed. To overcome this flaw, I present an algorithm which uses both the geometry of the landslide polygon minimum oriented bounding box and a digital elevation model of the landslide topography for identifying the long vs. wide landslides. I tested the proposed algorithm for a landslide inventory which covers 131.1 km2 of the Moldavian Plateau, eastern Romania. This inventory contains 1327 landslides, of which 518 were manually classified as long and 809 as wide. In a first step, the difference in elevation of the length and width of the minimum oriented bounding box is used to separate long landslides from wide landslides (long landslides having the greatest elevation difference along the length of the bounding box). In a second step, the long landslides are checked as to whether their length is greater than the length of flow downslope (estimated with a flow-routing algorithm), in which case the landslide is classified as wide. By using this approach, the area under the Receiver Operating Characteristic curve value for the classification of the long vs. wide landslides is 87.8 %. An intensive review of the misclassified cases and the challenges of the proposed algorithm is made, and discussions are included about the prospects of improving the approach with further steps, to reduce the number of misclassifications.

scholarly journals Digital Elevation Model Quality Assessment Methods: A Critical Review

2020 ◽  
Vol 12 (21) ◽  
pp. 3522
Author(s):  
Laurent Polidori ◽  
Mhamad El Hage
Keyword(s):  
Quality Assessment ◽  
Assessment Methods ◽  
Internal Quality ◽  
Surface Model ◽  
Model Quality ◽  
Topographic Features ◽  
Digital Elevation ◽  
Elevation Model ◽  
User Perspectives

Digital elevation models (DEMs) are widely used in geoscience. The quality of a DEM is a primary requirement for many applications and is affected during the different processing steps, from the collection of elevations to the interpolation implemented for resampling, and it is locally influenced by the landcover and the terrain slope. The quality must meet the user’s requirements, which only make sense if the nominal terrain and the relevant resolution have been explicitly specified. The aim of this article is to review the main quality assessment methods, which may be separated into two approaches, namely, with or without reference data, called external and internal quality assessment, respectively. The errors and artifacts are described. The methods to detect and quantify them are reviewed and discussed. Different product levels are considered, i.e., from point cloud to grid surface model and to derived topographic features, as well as the case of global DEMs. Finally, the issue of DEM quality is considered from the producer and user perspectives.

Modeling of the spatial distribution of the vector Aedes Aegypti, transmitter of the Zika Virus in continental Ecuador by the application of GIS tools

Bionatura ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 1314-1327
Author(s):  
Mario Bolivar Balseca Carrera ◽  
Oswaldo Padilla Almeida ◽  
Theofilos Toulkeridis
Keyword(s):  
Aedes Aegypti ◽  
Zika Virus ◽  
Characteristic Curve ◽  
Confusion Matrix ◽  
Virus Transmission ◽  
Predictive Performance ◽  
Actual Distribution ◽  
Gis Tools ◽  
Presence Data ◽  
Epidemiological Risk

In recent years Ecuador has suffered from the Zika virus. Geo-software and statistical software allowed the probabilistic identification of suitable ecological niche species, such as the vector Aedes aegypti, which is the leading cause of the Zika virus transmission, depending on the dependent and independent variables. These models require pre-weighted input, normalized, and rasterized inputs to continue the validation process to estimate their predictive performance through several statistics such as the confusion matrix or the Receiver Operating Characteristic Curve (ROC). It resulted that the Maxent method has been with the higher predictive performance with a value of Area Under Curve (AUC) = 0.998, which describes the areas of Zika with a greater probability of the transmission vector resembling the actual distribution of the species as a function of the presence data and the predictor variables. A large part of the Ecuadorian coastal territory yielded a statistical-based, probabilistic presence of the vector, being the most vulnerable before a possible epidemiological risk.

scholarly journals Geophysical analysis of transverse ridges and internal structure at Lone Peak Rock Glacier, Big Sky, Montana, USA

2014 ◽  
Vol 60 (221) ◽  
pp. 453-462 ◽  
Author(s):  
Caitlyn Florentine ◽  
Mark Skidmore ◽  
Marvin Speece ◽  
Curtis Link ◽  
Colin A. Shaw
Keyword(s):  
Genetic Relationships ◽  
The Body ◽  
Rock Glacier ◽  
Glacier Surface ◽  
Topographic Features ◽  
Digital Elevation ◽  
Rock Glaciers ◽  
Composition Structure ◽  
Elevation Model ◽  
Ground Penetrating

AbstractRock glaciers are periglacial alpine landforms that are found in many locations worldwide. Whereas well-developed models of deformation are established for traditional alpine glaciers, rock glacier deformation is poorly understood. Geophysical data from Lone Peak Rock Glacier (LPRG), southwest Montana, USA, are paired with lidar bare-earth 1 m digital elevation model (DEM) analysis to explore potential genetic relationships between internal composition, structure and regularly spaced arcuate transverse ridges expressed at the rock glacier surface. The internal composition of LPRG is heterogeneous, with frozen debris and clean ice overlain by an unconsolidated talus mantle. Upslope-dipping, clearly distinguished reflectors in the ground-penetrating radar (GPR) longitudinal survey at LPRG correspond to transverse ridges. The spacing and slope of individual features at the surface and in the subsurface were measured and compared and are found to be similar. The structures observed at LPRG and other rock glaciers are similar to structures detected in glaciotectonically altered sediment, ice-cored moraines and other rock glacier settings. This finding suggests that transverse ridges on rock glaciers may be used as geomorphic indicators of internal deformation. This study contributes to the body of research on the application of GPR to rock glaciers, and is the first to directly pair and analyze individual surface topographic features with internal structures.

scholarly journals Assessment of landslide risk in the mountainous area. Case study: Bumiaji Sub-District

2021 ◽  
Vol 916 (1) ◽  
pp. 012009
Author(s):  
A R A Prasetya ◽  
T A Rachmawati ◽  
F Usman
Keyword(s):  
Secondary Data ◽  
Risk Level ◽  
Landslide Risk ◽  
Mountainous Area ◽  
Tourist Destinations ◽  
Digital Elevation ◽  
Medium Level ◽  
Hazard Level ◽  
Elevation Model ◽  
High Level

Abstract Throughout 2016-2021, there were 31 landslides that have caused physical, economic, and social damages. Bumiaji Sub-District has several tourist destinations that are potentially exposed to landslides. This study aims to create a landslide risk map in Bumiaji Sub-District. This research was conducted during the COVID-19 pandemic situation. Therefore, the data collected was secondary data obtained from Google satellite images, Google Street View, the digital elevation model from the National Geospatial Institution, and other literature reviews. The data was then analysed using a landslide risk assessment based on Perka BNPB Number 2/2012. The results of this risk analysis show that Bumiaji Sub-District is dominated by low-level risk (48%), followed by high-level risk (30%), and medium-level risk (15%). High-risk level is affected by high hazards and vulnerabilities, especially in Giripurno Village. High hazard level is affected by high intensity of rainfall, slope degree, the sensitivity of soil to erosion, and the type of land cover. High vulnerabilities are affected by physical, social, and economic aspects susceptible to losses.

scholarly journals Map of the terminal moraine of the Werenskioldbreen glacier (South-West Spitsbergen) from 2015

2018 ◽  
Vol 29 ◽  
pp. 00029 ◽  
Author(s):  
Laura Downar-Zapolska ◽  
Tadeusz Głowacki
Keyword(s):  
Complex Terrain ◽  
Large Scale ◽  
Terminal Moraine ◽  
Topographic Features ◽  
Contour Lines ◽  
Digital Elevation ◽  
Field Notes ◽  
Glacial River ◽  
Elevation Model ◽  
West Spitsbergen

The first direct field measurement of the entire terminal moraine of the Werenskioldbreen glacier on Spitsbergen took place at the end of July and the beginning of August 2015. The results of the measurements were the basis for the development of the large-scale terminal moraine map. The article presents the stages of map creation and editing based on measurement points established by the GNSS method. The map editing required knowledge of the morphologically complex terrain. Key documentation was field notes and documentary photographs, enabling the cartographic interpretation of the varied topographic features of the terrain's surface. Based on the documentation, the water bodies on the moraine were located, the outline of the structure and the boundary points were executed and the latter were excluded from the triangulation process. The glacial river was also excluded from triangulation, which allowed a DTM to be developed. An important step in point cloud mapping was to generate a topologically correct digital elevation model of satisfactory accuracy. On the basis of the DTM, contour lines were generated showing the topographic features of the terrain's surface. The printable resultant map's scale is 1: 5000; it is in the UTM coordinate system, in the 33X zone. Complementing the content of the map, a grid of geographic coordinates, a kilometer grid, and map key descriptions were added.

scholarly journals Classification of Areas Suitable for Fish Farming Using Geotechnology and Multi-Criteria Analysis

2019 ◽  
Vol 8 (9) ◽  
pp. 394 ◽  
Author(s):  
Francisco ◽  
Corrêia ◽  
Feiden
Keyword(s):  
Regional Planning ◽  
Fish Farming ◽  
Public Institutions ◽  
Analytic Hierarchy ◽  
Digital Elevation ◽  
Using Data ◽  
Elevation Model ◽  
Hierarchy Process ◽  
Aquaculture Development

This study proposed a method for identifying areas appropriate for fish farming in ground-excavated ponds using data obtained from public institutions. The method was applied to three cities located in the central-southern region of Paraná State, Brazil. In order to select appropriate areas, a geographic information system (GIS) was created using data from a digital elevation model (DEM), as well as data on soil occupation and type. A variable reclassification model (VRM) was created, and the analytic hierarchy process (AHP) method was applied to establish weights for a multi-criteria assessment of the factors. Non-classifiable areas and areas with constraints were identified and removed from the analysis. The sites classified as highly suitable or suitable represented 33.270.79 ha (18.71% of the total area), while the restricted areas represented 54,427.91 ha (30.60% of the total area). This method may represent a useful tool for decision making in the context of regional planning and may be used in the establishment of public policy and in the allocation of resources for aquaculture development.

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