Geomorphometric analysis of Olkhon island region’s relief

2021 ◽  
Vol 972 (6) ◽  
pp. 37-46
Author(s):  
M.Y. Opekunova ◽  
Yu.V. Vanteeva ◽  
S.V. Solodyankina
Keyword(s):  
Spatial Distribution ◽  
Baikal Region ◽  
Total Curvature ◽  
Climatic Conditions ◽  
Middle Level ◽  
Low Intensity ◽  
Digital Elevation ◽  
Landslide Processes ◽  
Elevation Model ◽  
Geomorphometric Parameters

The use of geomorphometric analysis to obtain relevant data and their interpretation in geomorphological and geographical studies is becoming more widespread in recent times. In this study, such an analysis is used for the Priolkhonsky plateau (Western Baikal region), whose territory has recently been subjected to intense recreational impact. Under such conditions, it becomes relevant to determine the erosion-accumulative potential of the territory, its subsequent regionalization, as well as the possibility of using the obtained results in landscape-recreational zoning. The surface curvature maps were made using a digital elevation model based on ALOS data with a resolution of 30 m. Using geoinformation analysis, slope steepness, horizontal, vertical, and general curvature maps were obtained, and statistical coefficients of these indicators for the study area were determined. A geomorphological interpretation of the areas spatial distribution with different values of curvature was carried out. The analysis of the territory geomorphometric parameters showed that denudation processes prevail within the study area. It was also determined that the territory under favorable climatic conditions could have a significant potential for the development of erosion-accumulative processes. Areas of accumulation associated with the development of linear erosion forms, gullies along unpaved roads, were identified. Areas with the maximum values of curvature in the summit level of the relief have a high potential for the development of landslide processes. In the middle level of relief with positive values of the total curvature, prevail low-intensity processes (downwash, creeping).

scholarly journals Status of Major Glaciers of Hunza River Basin, Under Changing Climatic Conditions of Pakistan Over the Period of (1990-2018)

2021 ◽  
Author(s):  
Sajid Ali ◽  
Garee Khan ◽  
Wajid Hassan ◽  
Javed Akhter Qureshi ◽  
Iram Bano
Keyword(s):  
River Basin ◽  
Primary Source ◽  
Climatic Conditions ◽  
Climate Data ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Digital Elevation ◽  
Remote Sensing Techniques ◽  
Elevation Model ◽  
Hunza River

Abstract Ice masses and snow of Hunza River Basin (HRB) are an important primary source of fresh water and lifeline for downstream inhabitants. Changing climatic conditions seriously put an impact on these available ice and snow masses. These glaciers may affect downstream population by glacial lake outburst floods (GLOF) and surge events due to climatic variation. So, monitoring of these glaciers and available ice masses are important. This research delivers an approach for selected glaciers of the Hunza river basin. An attempt is made in this study using Landsat (OLI, ETM, ETM+, TM), digital elevation model (DEM), Geographic Information System and Remote Sensing techniques (RS&GIS) techniques. We delineated 27 glaciers within HRB from the period of 1990-2018. These glaciers' total area is about 2589.75 ±86km 2 in 1990 and about 2565.12 ±68km 2 in 2018. Our results revealed that from 2009 to 2015, glacier coverage of HRB advanced with a mean annual advance rate of 2.22±0.1 km 2 a -1 . Conversely, from 1994 to 1999, the strongest reduction in glacier area with a mean rate of - 3.126±0.3km 2 a -1 is recorded. The glaciers of HRB are relatively stable compared to Hindukush, Himalayan and Tibetan Plateau (TP) region of the world. The steep slope glacier's retreat rate is more than that of gentle slope glaciers, and the glaciers below elevation of 5000 m above sea level change significantly. Based on climate data from 1995-2018, HRB shows a decreasing trend in temperature and increasing precipitation. The glacier area's overall retreat is due to an increase in summer temperature while the glacier advancement is induced possibly by winter and autumn precipitation.

scholarly journals Geomorphometry of drainage basins: a global view from the Shuttle Radar Topography Mission

2011 ◽  
Vol 8 (1) ◽  
pp. 1929-1949
Author(s):  
P. L. Guth
Keyword(s):  
Digital Elevation Model ◽  
Shuttle Radar Topography Mission ◽  
Global Distribution ◽  
Drainage Basins ◽  
Global View ◽  
Digital Elevation ◽  
Elevation Model ◽  
Geomorphometric Parameters

Abstract. A suite of 42 geomorphometric parameters for each of 26 272 drainage basins larger than 100 km2 from the Hydrosheds Shuttle Radar Topography digital elevation model shows the global distribution of Strahler order for streams and drainage basins; the largest basins are order 9. Many common parameters depend both on the size of the basin, and the scale of the digital elevation model used for the computations. These drainage basins display the typical longitudinal stream profiles, but the major basins tend to be more convex than the smaller basins.

A novel multiple flow direction algorithm for computing the topographic wetness index

2012 ◽  
Vol 43 (1-2) ◽  
pp. 135-145 ◽  
Author(s):  
Bin Yong ◽  
Li-Liang Ren ◽  
Yang Hong ◽  
Jonathan J. Gourley ◽  
Xi Chen ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Flow Direction ◽  
Contour Length ◽  
Topographic Wetness Index ◽  
Wetness Index ◽  
Digital Elevation ◽  
Surface Saturation ◽  
Mathematical Equations ◽  
Downslope Flow ◽  
Elevation Model

The topographic wetness index (TWI), frequently used in approximately characterizing the spatial distribution of soil moisture and surface saturation within a watershed, has been widely applied in topography-related geographical processes and hydrological models. However, it is still questionable whether the current algorithms of TWI can adequately model the spatial distribution of topographic characteristics. Based upon the widely-used multiple flow direction approach (MFD), a novel MFD algorithm (NMFD) is proposed for improving the TWI derivation using a Digital Elevation Model (DEM) in this study. Compared with MFD, NMFD improves the mathematical equations of the contributing area and more precisely calculates the effective contour length. Additionally, a varying exponent strategy is adopted to dynamically determine the downslope flow-partition exponent. Finally, a flow-direction tracking method is employed to address grid cells in flat terrain. The NMFD algorithm is first applied to a catchment located upstream of the Hanjiang River in China to demonstrate its accuracy and improvements. Then NMFD is quantitatively evaluated by using four types of artificial mathematical surfaces. The results indicate that the error generated by NMFD is generally lower than that computed by MFD, and NMFD is able to more accurately represent the hydrological similarity of watersheds.

scholarly journals Modeling and Classification of Alluvial Fans with DEMs and Machine Learning Methods: A Case Study of Slovenian Torrential Fans

2021 ◽  
Vol 13 (9) ◽  
pp. 1711
Author(s):  
Matej Babič ◽  
Dušan Petrovič ◽  
Jošt Sodnik ◽  
Božo Soldo ◽  
Marko Komac ◽  
...  
Keyword(s):  
Machine Learning ◽  
Debris Flow ◽  
Human Life ◽  
Alluvial Fans ◽  
Digital Elevation ◽  
Elevation Model ◽  
Flow Activity ◽  
Geomorphometric Parameters

Alluvial (torrential) fans, especially those created from debris-flow activity, often endanger built environments and human life. It is well known that these kinds of territories where human activities are favored are characterized by increasing instability and related hydrological risk; therefore, treating the problem of its assessment and management is becoming strongly relevant. The aim of this study was to analyze and model the geomorphological aspects and the physical processes of alluvial fans in relation to the environmental characteristics of the territory for classification and prediction purposes. The main geomorphometric parameters capable of describing complex properties, such as relative fan position depending on the neighborhood, which can affect their formation or shape, or properties delineating specific parts of fans, were identified and evaluated through digital elevation model (DEM) data. Five machine learning (ML) methods, including a hybrid Euler graph ML method, were compared to analyze the geomorphometric parameters and physical characteristics of alluvial fans. The results obtained in 14 case studies of Slovenian torrential fans, validated with data of the empirical model proposed by Bertrand et al. (2013), confirm the validity of the developed method and the possibility to identify alluvial fans that can be considered as debris-flow prone.

scholarly journals An Examination of an Enhanced Remote Sensing Method for Agent Attribution of Forest Disturbance

2020 ◽  
Author(s):  
Hugh Marshall Worsham
Keyword(s):  
Remote Sensing ◽  
Sierra Nevada ◽  
Forest Disturbance ◽  
Climatic Conditions ◽  
Temporal Segmentation ◽  
Digital Elevation ◽  
Accuracy Difference ◽  
Elevation Model ◽  
Occurrence Matrix ◽  
Texture Metrics

AbstractPatterns of disturbance in Sierra Nevada forests are shifting as a result of changing climate and land uses. These changes have underscored the need for a monitoring system that both detects disturbances and attributes them to different agents. Addressing this need will aid forest management and conservation decision-making, potentially enhancing forests’ resilience to changing climatic conditions. In addition, it will advance understanding of the patterns, drivers, and consequences of forest disturbance in space and time. This study proposed and evaluated an enhanced method for disturbance agent attribution. Specifically, it tested the extent to which textural information could improve the performance of an ensemble learning method in predicting the agents of disturbance from remote sensing observations. Random Forest (RF) models were developed to attribute disturbance to three primary agents (fire, harvest, and drought) in Stanislaus National Forest, California, U.S.A., between 1999 and 2015. To account for spectral behavior and topographical characteristics that regulate vegetation and disturbance dynamics, the models were trained on predictors derived from both the Landsat record and from a digital elevation model. The predictors included measurements of spectral change acquired through temporal segmentation of Landsat data; measurements of patch geometry; and a series of landscape texture metrics. The texture metrics were generated using the Grey-Level Co-Occurrence Matrix (GLCM). Two models were produced: one with GLCM texture metrics and one without. The per-class and overall accuracies of each model were evaluated with out-of-bag (OOB) observations and compared statistically to quantify the contribution of texture metrics to classification skill. Overall OOB accuracy was 72.0% for the texture-free model and 72.2% for the texture-dependent model, with no significant accuracy difference between them. Spatial patterns in prediction maps cohered with expectations, with most harvest concentrated in mid-elevation forests and fire and stress co-occurring at lower elevations. Altogether, the method yielded adequate identification of disturbance and moderate attribution accuracy for multiple disturbance agents. While textures did not contribute meaningfully to model skill, the study offers a strong foundation for future development, which should focus on improving the efficacy of the model and generalizing it for systems beyond the Central Sierra Nevada.

scholarly journals Dimensionless Geomorphometry and Discharge in the Ikpa River Basin, Nigeria

2018 ◽  
pp. 1-13
Author(s):  
Ikpong Sunday Umo ◽  
M. C. Ike ◽  
Ifeanyi G. Ukwe
Keyword(s):  
River Basin ◽  
Graphical Analysis ◽  
Elongation Ratio ◽  
Watershed Development ◽  
Digital Elevation ◽  
Geospatial Tools ◽  
The Government ◽  
Elevation Model ◽  
Basin Area ◽  
Geomorphometric Parameters

This study evaluates the relationships between dimensionless basin geomorphometry and discharge in the Ikpa River. The basin was stratified into seven sub-units using [1] scheme. Geospatial tools were used in generating data for the digital elevation model, while dimensionless geomorphometric parameters were generated from topographic maps (sheet 322 NE; sheet 322 SE; sheet 323 SW; and sheet 331 NW) of the basin area drawn on a scale of 1.50,000. The sampled sub-basins were gauged and discharge measured by a surface float. Graphical analysis of discharge revealed wide variations between months and in seasons across sub-basins with the rainy season attracting highest volume of discharge and the corresponding fluvial processes. The regression analysis yields a coefficient of multiple determination (R) of 0.937, signifying a very high effect expressed by 87.8 of the proportion of variance in dimensionless geomorphometric parameters on discharge in Ikpa River Basin. Also, the computed F value yields 1.439, while the Table value tested at (0.05)5/2 confident level offers 19.30. The result led to the conclusion that variations in relief ratio, average bifurcation ratio, circularity ratio, elongation ratio and form factor have a significant effect on discharge in Ikpa River Basin. This paper recommends for prompt installations of state of the art river gauging and monitoring facilities to provide the needed information to the government, researchers, and individuals for the sustainable land and watershed development options (dam and irrigation) in the coastal plain of Ikpa River basin.  

scholarly journals Computer-assisted cartography using topographic properties: precision and accuracy of local soil maps in central Mexico

2011 ◽  
Vol 35 (3) ◽  
pp. 683-691
Author(s):  
Gustavo Cruz-Cárdenas ◽  
Carlos Alberto Ortiz-Solorio ◽  
Enrique Ojeda-Trejo ◽  
Juan Felipe Martínez-Montoya ◽  
Erasto Domingo Sotelo-Ruiz ◽  
...  
Keyword(s):  
Climatic Conditions ◽  
Slope Aspect ◽  
Computer Assisted ◽  
Central Mexico ◽  
Digital Elevation ◽  
Local Soil ◽  
Topographical Feature ◽  
Precision And Accuracy ◽  
Elevation Model ◽  
Properties Of Soil

Map units directly related to properties of soil-landscape are generated by local soil classes. Therefore to take into consideration the knowledge of farmers is essential to automate the procedure. The aim of this study was to map local soil classes by computer-assisted cartography (CAC), using several combinations of topographic properties produced by GIS (digital elevation model, aspect, slope, and profile curvature). A decision tree was used to find the number of topographic properties required for digital cartography of the local soil classes. The maps produced were evaluated based on the attributes of map quality defined as precision and accuracy of the CAC-based maps. The evaluation was carried out in Central Mexico using three maps of local soil classes with contrasting landscape and climatic conditions (desert, temperate, and tropical). In the three areas the precision (56 %) of the CAC maps based on elevation as topographical feature was higher than when based on slope, aspect and profile curvature. The accuracy of the maps (boundary locations) was however low (33 %), in other words, further research is required to improve this indicator.

scholarly journals DISTRIBUCIÓN ESPACIAL DEL BOSQUE SECO TROPICAL EN EL VALLE DEL CAUCA, COLOMBIA

2015 ◽  
Vol 20 (3) ◽  
pp. 141-153 ◽  
Author(s):  
Diana Patricia ALVARADO-SOLANO ◽  
Joel Tupac OTERO OSPINA
Keyword(s):  
Spatial Distribution ◽  
Tropical Dry Forest ◽  
Dry Forest ◽  
Transition Zones ◽  
Digital Elevation ◽  
Adaptive Mechanisms ◽  
Restoration Strategies ◽  
Valle Del Cauca ◽  
Elevation Model ◽  
Del Rio

<p>En el departamento del Valle del Cauca, la distribución de Bosque Seco Tropical (BsT) se ha asociado al valle geográfico del río Cauca ubicado en la zona plana. Actualmente en esta zona, su cobertura se ha reducido a pocos relictos que se encuentran bajo alguna figura de conservación y mantienen áreas representativas de las formaciones vegetales típicas de este bioma. Este trabajo se enfocó en el reconocimiento de la distribución espacial de formaciones vegetales de BsT en el departamento del Valle del Cauca. Se empleó información cartográfica secundaria para reconocer los biomas, ecosistemas y usos del suelo del área de estudio y en zonas adyacentes del piedemonte y montañas. Un modelo digital de elevaciones fue utilizado para realizar análisis altitudinales. En un sistema de información geográfico se aplicaron técnicas de geoprocesamiento y análisis geoespacial entre la información cartográfica y satelital. Los resultados evidencian que pese al avanzado deterioro de las coberturas de bosque seco en la zona plana, alrededor del 80 % se localiza en ecosistemas de montaña, específicamente en zonas de transición hacia bosques húmedos.  A futuro, el potencial de estas áreas deberá evaluarse en para ser incluidas estrategias de conservación y restauración del bosque seco así como en el diseño de procesos adaptativos frente al cambio climático.</p><p><strong>Spatial Distribution of Tropical Dry Forest in Valle Del Cauca, Colombia</strong></p><p>The distribution of tropical dry forest in the department of Valle del Cauca, has been associated with the geographic Cauca valley. Currently in this area, dry forest coverages has been reduced to a few relicts, which are found under some protection figure and also hold representative areas of the typical vegetation of this biome. This work is focused on the spatial distribution of BsT vegetation formations in the Department of Valle del Cauca. Secondary cartographic information was used to recognize biomes, ecosystems and land uses in the study area and over adjacent areas of the piedmont and mountains. A digital elevation model was used to perform altitudinal analysis. The results showed that despite the high human disturbance of dry forest in the flat area, about 80 % is located in montain ecosystems, specially on transition zones towards humid forests. In the future, the potential of these areas to be included in dry forest conservation and restoration strategies and also adaptive mechanisms in facing climate change should be evaluated.</p>

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