scholarly journals Automatic Mapping and Characterisation of Linear Depositional Bedforms: Theory and Application Using Bathymetry from the North West Shelf of Australia

2022 ◽  
Vol 14 (2) ◽  
pp. 280
Author(s):  
Ulysse Lebrec ◽  
Rosine Riera ◽  
Victorien Paumard ◽  
Michael J. O'Leary ◽  
Simon C. Lang
Keyword(s):  
North West ◽  
The North ◽  
Digital Elevation ◽  
Automated Measurements ◽  
Automatic Mapping ◽  
Neighbourhood Analysis ◽  
Study Support ◽  
Elevation Model ◽  
Definition Of ◽  
Automated Methods

Bedforms are key components of Earth surfaces and yet their evaluation typically relies on manual measurements that are challenging to reproduce. Several methods exist to automate their identification and calculate their metrics, but they often exhibit limitations where applied at large scales. This paper presents an innovative workflow for identifying and measuring individual depositional bedforms. The workflow relies on the identification of local minima and maxima that are grouped by neighbourhood analysis and calibrated using curvature. The method was trialed using a synthetic digital elevation model and two bathymetry surveys from Australia’s northwest marine region, resulting in the identification of nearly 2000 bedforms. The comparison of the metrics calculated for each individual feature with manual measurements show differences of less than 10%, indicating the robustness of the workflow. The cross-comparison of the metrics resulted in the definition of several sub-types of bedforms, including sandwaves and palaeoshorelines, that were then correlated with oceanic conditions, further corroborating the validity of the workflow. Results from this study support the idea that the use of automated methods to characterise bedforms should be further developed and that the integration of automated measurements at large scales will support the development of new classification charts that currently rely solely on manual measurements.

scholarly journals Glacial debris cover and melt water production for glaciers in the Altay, Russia

2011 ◽  
Vol 5 (1) ◽  
pp. 401-430 ◽  
Author(s):  
C. Mayer ◽  
A. Lambrecht ◽  
W. Hagg ◽  
Y. Narozhny
Keyword(s):  
Ice Melt ◽  
The North ◽  
Altay Mountains ◽  
Digital Elevation ◽  
Glacier Runoff ◽  
Debris Cover ◽  
Continuous Mass ◽  
Different Depths ◽  
The 1960S ◽  
Elevation Model

Abstract. Glaciers are important water storages on a seasonal and long-term time scale. Where high mountains are surrounded by arid lowlands, glacier runoff is an important source of water during the growing season. This situation can be found in the Altay mountains in Southern Siberia, where the recent glacierization of >700 km2 is subject to continuous mass loss, even though the shrinking is comparably slow. The glacier retreat is accompanied by an extension of supra-glacial moraine, which itself strongly influences ablation rates. To quantify these effects, the spatial evolution of debris cover since 1952 was analysed for three glaciers in the North Chuya Ridge using satellite and airborne imagery. In summer 2007, an ablation experiment was carried out on debris covered parts of Maliy Aktru glacier. Thermistors in different depths within the moraine provided data to calculate thermal resistance of the debris. A set of ablation stakes was installed at locations with differing debris thickness and observed regularly throughout the entire melt season. Air temperature from an AWS was used to calculate degree day factors in dependence of the debris thickness. To take into account the shading effect of surrounding walls and peaks, the potential solar radiation and its evolution throughout the summer was determined from a digital elevation model. This allows us to extrapolate our measurements from Maliy Aktru to the other two glaciers of the Aktru basin and to estimate basin melt rates. In addition accumulated ice melt was derived for 12 glaciers in the North Chuya Range. Changes in summer runoff from the 1960s are compared to the results from our melt model and the evolution of debris cover is analysed in respect to the melt activity.

scholarly journals A Case Study of Digital Elevation Model-Based Slope Stability Assessment on Managed Forestland in the Oregon Coast Range

2006 ◽  
Vol 21 (4) ◽  
pp. 195-202
Author(s):  
Marvin R. Pyles ◽  
Mari Kramer
Keyword(s):  
Slope Stability ◽  
Digital Elevation Model ◽  
Low Risk ◽  
Correct Prediction ◽  
Stability Assessment ◽  
Forest Management Planning ◽  
Model Based ◽  
The North ◽  
Digital Elevation ◽  
Elevation Model

Abstract An aerial photo-based inventory of landslides on recently harvested and reforested land after a significant landslide-producing storm in February 1996, was compared with a digital elevation model-based assessment of slope stability (shallow landsliding stability model [SHALSTAB]) for Confederated Tribes of Siletz Indians (CTSI) and surrounding forestland. The SHALSTAB predictions of landslide locations did not correlate well with the locations of observed landslides. Eighty-nine percent of the landslides on the more stable landform in the southern portion of the CTSI ownership occurred on land that SHALSTAB indicated to be at a low risk of landsliding. Seventy-two percent of the landslides on the less stable landform to the north occurred on land that SHALSTAB indicated to be at a low risk of landsliding. Conversely, only 11 and 28%, respectively, of the observed landslides occurred on lands predicted to be “chronically unstable” or at “high risk” by SHALSTAB. This level of correct prediction of landsliding was judged to be unacceptable for SHALSTAB to be used for slope stability assessment as a part of forest management planning. West. J. Appl. For. 21(4):195–202.

scholarly journals Geodetic work at the archaeological site Tell el-Retaba

2018 ◽  
Vol 17 (2) ◽  
pp. 65-80
Author(s):  
Eva Stopková
Keyword(s):  
Spatial Data ◽  
Statistical Modelling ◽  
Archaeological Site ◽  
The North ◽  
Digital Elevation ◽  
North Eastern ◽  
Elevation Model ◽  
Modern Technologies

The paper summarizes the geodetic contribution for the Slovak team within the joint Polish-Slovak archaeological mission at Tell el-Retaba in Egypt. Surveying work at archaeological excavations is usually influenced by somewhat specific subject of study and extreme conditions, especially at the missions in the developing countries. The case study describes spatial data development according to the archaeological conventions in order to document spatial relationships between the objects in excavated trenches. The long-term sustainability of surveying work at the site has been ensured by detailed metadata recording. Except the trench mapping, Digital Elevation Model has been calculated for the study area and for the north-eastern part of the site, with promising preliminary results for further detection and modelling of archaeological structures. In general, topographic mapping together with modern technologies like Photogrammetry, Satellite Imagery, and Remote Sensing provide valuable data sources for spatial and statistical modelling of the sites; and the results offer a different perspective for the archaeological research.

scholarly journals Nation-wide, general-purpose delineation of geomorphological slope units in Italy

2018 ◽  
Author(s):  
Massimiliano Alvioli ◽  
Ivan Marchesini ◽  
Fausto Guzzetti
Keyword(s):  
Adaptive Algorithm ◽  
Central Italy ◽  
Optimization Procedure ◽  
General Purpose ◽  
General Requirement ◽  
Italian Peninsula ◽  
Slope Unit ◽  
Digital Elevation ◽  
Elevation Model ◽  
Definition Of

Slope units are portions of terrain, defined by the general requirement of maximizing homogeneity within a single unit and heterogeneity between different ones. Slope units are being used to describe a variety of processes and to assess different natural hazards. An unambiguous and reproducible definition of slope units based on quantitative hydrologic and topographic criteria was previously provided by the r.slopeunits software to automatically draw slope unit polygons on a digital surface. The software contains an adaptive algorithm allowing for a flexible yet well-defined slope unit delineation, by means of an iterative procedure. It requires a digital elevation model and a few input parameters, whose values must be optimized in a sound way, by means of multiple software runs and a proper objective function. The code is designed to quickly produce results on large areas, and in this work we devised an optimization algorithm to delineate slope units over the whole Italian peninsula. We outline the rationale of the optimization procedure for a general purpose slope unit delineation within very large areas. We present preliminary results in Central Italy, specifically a slope unit mosaic in the whole area affected by the 2016 earthquake sequence. The procedure represents a well-defined framework for slope unit delineation over the whole of Italy.

scholarly journals Lithological and geomorphological indicators of glacial genesis in the upper Quaternary strata, Nadym River basin, Western Siberia

Solid Earth ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 2047-2074
Author(s):  
Oleg Sizov ◽  
Anna Volvakh ◽  
Anatoly Molodkov ◽  
Andrey Vishnevskiy ◽  
Andrey Soromotin ◽  
...  
Keyword(s):  
River Basin ◽  
Western Siberia ◽  
Quaternary Sediments ◽  
Quaternary Sediment ◽  
The North ◽  
Digital Elevation ◽  
Relief Formation ◽  
Basic Characteristics ◽  
Elevation Model ◽  
Quartz Grains

Abstract. Analysing the genesis of Quaternary sediments is important for understanding the glaciation history and development of marine sediments in the northern part of Western Siberia. The problem is relevant since there is no consistent concept of the Quaternary sediment genesis in the north of Western Siberia. The formation of sediments is associated with marine, glacial and interglacial sedimentation conditions. The research objective is to identify the persistent features characterising the conditions of sedimentation and relief formation using the Nadym River basin as an example. The best method for studying this problem is a comprehensive analysis of the lithological, chronostratigraphic, petrographic and geomorphological studies of the Quaternary sediment upper strata. This study provides data from the analysis of the basic characteristics of quartz grains at the site. The rounding and morphology of the quartz grains provide evidence of possible glacial processing of some of the site strata. A petrographic study of selected boulder samples was performed. Some of them, by the shape and presence of striation, can be attributed to ice basins. The first use of a detailed digital elevation model applied to the study area made it possible to identify specific relief forms that could very likely be created during glaciations. Based on the analysis, we propose to consider the vast lake alluvial plains in the Nadym River basin as periglacial regions. This idea lays the lithological framework for understanding the reasons for the formation of the modern landscape structure. The materials and descriptions provided are of interest to researchers of Quaternary sediments, topography, vegetation and soil cover, particularly researchers engaged in revising the history of the natural environment development in the north of Western Siberia.

scholarly journals An Overview of the Geomorphological Characteristics of the Pergamon Micro-Region (Bakırçay and Madra River Catchments, Aegean Region, West Turkey)

Land ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 667
Author(s):  
Xun Yang ◽  
Fabian Becker ◽  
Daniel Knitter ◽  
Brigitta Schütt
Keyword(s):  
Satellite Images ◽  
Sediment Accumulation ◽  
The North ◽  
Parallel Change ◽  
Digital Elevation ◽  
Engineering Measures ◽  
Multiple Materials ◽  
Elevation Model ◽  
Landscape Units ◽  
River Catchments

Current landforms are the basis for understanding past geomorphodynamics and human activities. Based on multiple materials and methods, including geomorphometric analyses of a digital elevation model and visual interpretations of satellite images, different landscape units of the Bakırçay and Madra River catchments in the environs of ancient Pergamon are described. The area was mainly shaped by tectonics that formed a horst-and-graben structure; small Miocene horsts and NE-trending subgrabens in the Kozak and Yunt Dağı Mountains were separated by the NEE-trending Plio-Pleistocene Bergama Graben. The asymmetry in relief, drainage network, and sediment accumulation between the Kozak Mountains to the north and the Yunt Dağı Mountains to the south of the lower Bakırçay plain characterize the Pergamon Micro-Region. The regional relief characteristics, with wide flat basin and plateau areas, are suitable for agriculture. Complemented by its richness in natural resources, the Pergamon Micro-Region became a preferred settlement area, with evidence of human impact since the Hellenistic–Roman period at the latest. As a consequence of settlement activities, several landscape engineering measures were implemented simultaneously with a parallel change in morphodynamics.

Students’ perceptions of librarians as teachers of information literacy at a large African university

2020 ◽  
Vol 69 (6/7) ◽  
pp. 399-415
Author(s):  
Siviwe Bangani ◽  
Dina Mokgadi Mashiyane ◽  
Mathew Moyo ◽  
Boitumelo Masilo ◽  
Glenda Makate
Keyword(s):  
Undergraduate Students ◽  
Information Literacy ◽  
Effective Teachers ◽  
Information Overload ◽  
Content Type ◽  
North West ◽  
The North ◽  
Short Period ◽  
Study Support ◽  
The Subject

Purpose The purpose of this study is to determine the students’ perceptions of librarians as teachers of information literacy at the North-West University in South Africa. Design/methodology/approach The study used a survey research method in which online questionnaires were used to gather data from students who would have attended information literacy classes. Findings Students found librarians to be effective teachers of information literacy, and they found the subject to be very useful. However, some of the surveyed students felt that a lot of the subject was presented in a short period, which could easily result in exhaustion and information overload. The use of local or vernacular languages was also indicated as an area requiring the librarians’ attention for the teachers to be more effective. Practical implications The results of this study support the assessment of librarians as teachers by students to assist them (librarians) to refine their teaching methods and to make the conduct of information literacy worthwhile for the students. Social implications The outcomes of this study may be used to advocate for more information literacy (IL) contact time with the students by librarians when negotiating with faculty. Further, these results may be used to showcase the value placed by students to IL. Originality/value This study is a welcome addition to the scant literature on the quality of teaching delivered by the librarians and the assessment mechanisms used to provide feedback on students’ learning of IL. This study is a first of its kind comparing the perceptions of librarians’ teaching abilities by postgraduate and undergraduate students.

scholarly journals ГЕОМОРФОЛОГИЧЕСКИЙ ЭКОГЕОГРАФИЧЕСКИЕ ПЕРЕМЕННЫЕ, ОПРЕДЕЛЯЩИЕ ОСОБЕННОСТИ ЭКОЛОГИЧЕСКОЙ НИШИ ВАТОЧНИКА СИРИЙСКОГО (ASCLEPIAS SYRIACA L.)

2016 ◽  
Vol 6 (01) ◽  
pp. 243-275
Author(s):  
O. M. Kunah ◽  
O. S. Papka
Keyword(s):  
Remote Sensing Data ◽  
Agricultural Field ◽  
Asclepias Syriaca ◽  
Channel Network ◽  
Valley Bottom ◽  
Topographic Position Index ◽  
The North ◽  
Digital Elevation ◽  
Position Index ◽  
Elevation Model

<span>The role of geomorphological ecogeographical variables have been shown, which are received by means of the digital elevation model created on the basis of remote sensing data as markers of an ecological niche of weeds on an example common milkweed (</span><em>Asclepias syriaca</em><span> L.). The research range chooses territory which is in settlement Vovnjanka district (the Poltava region). The range has the linear sizes of 26 kilometres in a direction from the east on the west and 15 kilometres in a direction from the north on the south, the range total area makes 390 км</span><sup>2</sup><span>. As geomorphological variables the topographical wetness index, topographic position index, mass balance index, erosion LS-factor, direct and disseminated insolation, altitude above channel network, multiresolution valley bottom flatness, multiresolution ridge top flatness index, vector ruggedness measure have been considered. It is established, that on set of the geomorphological indicators received by means of digital model of a relief, it is possible to assert, that within a separate agricultural field a wide variety of microconditions which is caused by relief features is formed. Possibly, the variation of thermal and water modes, moisture redistribution, and also productivity mechanical processings of soil and efforts under the control of number of weeds make a background in which limits there is possible a moving of weed plants, including common milkweed.</span>

scholarly journals Evaluation of Active Tectonics in Northwest of Saveh

2021 ◽  
Author(s):  
Bahar Rezaeinahal ◽  
Mohsen PourKermani ◽  
Mehdy Zare ◽  
Maryam Dehbozorgi ◽  
Reza Nozaem
Keyword(s):  
Drainage Basin ◽  
Active Tectonics ◽  
Tectonic Activity ◽  
Drainage Basins ◽  
The North ◽  
Level Of Activity ◽  
Digital Elevation ◽  
Arc Gis ◽  
Elevation Model ◽  
Gis Software

Abstract The northwest zone of Saveh city is located in the fault zone of the Indes, Koosh e Nosrat, Avaj and Aipak. Indes faults, Cox Nosrat, Avaj and Aipak are considered as the major faults of central Iran, which are also active in the Quaternary and the last movements of these faults are attributed to the present covenant, therefore, the estimation of morphometri in order to identify the effect of active tectonics on the tectonic evolution of drainage basins seems necessary. Therefore, in this study, six important morphotectonic indexes were analyzed; longitudinal gradient of the river, asymmetry of drainage basin, hypometric integral, Drainage basin shape,the ratio of the width of the floor to the height of the valley and forehead of the mountain is discussed.to create the basins on the studied area, Arc Hydro software (Arc GIS software) has been used based on data from a digital elevation model, Then, 6 morphotectonic indexes have been compiled and classified on each of the basins.Finally, according to which the region has been classified into 4 categories of high, medium and low tectonic activity the, Active Tectonic Index (IAT) has been calculated.According to the IAT index, 5% of the study area shows very high tectonic activity, 25% of the studied area has high tectonic activity, the average tectonic activity has 65% and about 5% of the tectonic activity are low. In this study, the highest level of tectonic activity is in the north-eastern part of the region. In most of the sectors, the level of activity is high and moderate, which is related to the activity of Koshk E Nosrat, Aipak, Avaj faults.

Sign in / Sign up

Export Citation Format

Share Document