Approach for analyzing landslide and torrential flow hazard conditions in relation to landscape evolution in the northern Colombian Andes 

2021 ◽  
Author(s):  
Karolina Naranjo Bedoya ◽  
Edier Aristizábal ◽  
Daniel Hölbling
Keyword(s):  
Landscape Evolution ◽  
Tectonic Stress ◽  
Asymmetry Factor ◽  
Economic Losses ◽  
Landscape Characteristics ◽  
Colombian Andes ◽  
Digital Elevation ◽  
Dynamic Landscape ◽  
Quantitative Geomorphology ◽  
Drainage Texture

<p><span>Colombia is an equatorial country located in the northwestern corner of South America with characteristic and complex climatic and geologic settings, which contribute to a great diversity of landforms in the Colombian Andes. 65% of the Colombian population is concentrated in this mountainous terrain, where landslides and torrential flows are common. These natural hazards led to several tragic events over time. Their occurrence is favored by a very dynamic landscape made up of weak and highly weathered materials and affected by tectonic stress. In this study, we aim to gain a better understanding of morphometric control on the occurrence of landslides and torrential flows through process geomorphology and information derived from Digital Elevation Models (DEMs). Several morphometric indices related to drainage network, basin geometry, drainage texture, relief characteristics, asymmetry factor and others were calculated over 168 drainage basins in the northern Colombian Andes. We used quantitative geomorphology to find patterns of anomalies associated with landscape evolution and the occurrence of landslides and torrential flows. Understanding morphodynamics from morphogenesis is important to assess landslide and torrential flow hazard conditions in relation to landscape characteristics and evolution, to support hazard assessment, and consequently to reduce human and economic losses.<br>Keywords: Landslide, torrential flow, morphometric indices, mountainous terrains.</span></p>

scholarly journals Perspective – synthetic DEMs: A vital underpinning for the quantitative future of landform analysis?

2015 ◽  
Vol 3 (4) ◽  
pp. 587-598 ◽  
Author(s):  
J. K. Hillier ◽  
G. Sofia ◽  
S. J. Conway
Keyword(s):  
Conceptual Models ◽  
Landscape Evolution ◽  
A Priori ◽  
Morphological Properties ◽  
Governing Equations ◽  
Physical Processes ◽  
Digital Elevation ◽  
Dem Analysis ◽  
Future Potential ◽  
Detection And Quantification

Abstract. Physical processes, including anthropogenic feedbacks, sculpt planetary surfaces (e.g. Earth's). A fundamental tenet of geomorphology is that the shapes created, when combined with other measurements, can be used to understand those processes. Artificial or synthetic digital elevation models (DEMs) might be vital in progressing further with this endeavour in two ways. First, synthetic DEMs can be built (e.g. by directly using governing equations) to encapsulate the processes, making predictions from theory. A second, arguably underutilised, role is to perform checks on accuracy and robustness that we dub "synthetic tests". Specifically, synthetic DEMs can contain a priori known, idealised morphologies that numerical landscape evolution models, DEM-analysis algorithms, and even manual mapping can be assessed against. Some such tests, for instance examining inaccuracies caused by noise, are moderately commonly employed, whilst others are much less so. Derived morphological properties, including metrics and mapping (manual and automated), are required to establish whether or not conceptual models represent reality well, but at present their quality is typically weakly constrained (e.g. by mapper inter-comparison). Relatively rare examples illustrate how synthetic tests can make strong "absolute" statements about landform detection and quantification; for example, 84 % of valley heads in the real landscape are identified correctly. From our perspective, it is vital to verify such statistics quantifying the properties of landscapes as ultimately this is the link between physics-driven models of processes and morphological observations that allows quantitative hypotheses to be tested. As such the additional rigour possible with this second usage of synthetic DEMs feeds directly into a problem central to the validity of much of geomorphology. Thus, this note introduces synthetic tests and DEMs and then outlines a typology of synthetic DEMs along with their benefits, challenges, and future potential to provide constraints and insights. The aim is to discuss how we best proceed with uncertainty-aware landscape analysis to examine physical processes.

scholarly journals Condicionantes geomorfológicos e da cobertura da terra na ocorrência de movimentos de massa na região serrana do Rio de Janeiro / Geomorphological and cover land conditioning factors of the mass movements in the mountainous region of Rio de Janeiro

2019 ◽  
Vol 29 (56) ◽  
pp. 27 ◽  
Author(s):  
Cristiane Nunes Francisco ◽  
Raquel Conceição Carvalho ◽  
Carla Maciel Salgado
Keyword(s):  
Land Cover ◽  
Rio De Janeiro ◽  
Landscape Evolution ◽  
Southeastern Brazil ◽  
Economic Losses ◽  
Mass Movements ◽  
Mountainous Region ◽  
Conditioning Factors ◽  
Different Types ◽  
Morphological Variables

Movimentos de massa são processos de evolução da paisagem condicionados por fatores geológicos, geomorfológicos, hidrológicos, climáticos e da cobertura vegetal. A região Sudeste do Brasil destaca-se pela ocorrência de eventos catastróficos, pois combina a ocupação das encostas com as características fisiográficas que a deixam altamente suscetível a diferentes tipos de movimentos de massa, destacando-se os escorregamentos translacionais. Embora tenham um importante papel na evolução da paisagem, a ocorrência de movimentos de massa em áreas ocupadas por atividades antrópicas tem gerado inúmeras perdas humanas e prejuízos econômicos. Foi o que ocorreu em janeiro de 2011 na região serrana do Rio de Janeiro, atingida por fortes chuvas que desencadearam eventos de extrema magnitude, e provocaram, além de destruição e morte, marcas profundas (cicatrizes) na paisagem que podem auxiliar no estudo dos processos de movimentos de massa. Este trabalho, assim, tem como objetivo analisar as relações espaciais entre a morfologia das encostas e a cobertura da terra com a ocorrência dos movimentos de massa em janeiro de 2011 na região serrana fluminense. Para tanto, foi realizado um estudo na bacia do rio Roncador, Nova Friburgo (Estado do Rio de Janeiro), com a sobreposição entre o mapeamento das cicatrizes, das variáveis morfológicas das encostas e das classes de cobertura da terra. Os resultados mostram que as cicatrizes predominaram em encostas de forma côncava e íngremes, além de cobertas por vegetação densa, corroborando com a literatura que aponta a declividade e a forma da encosta como fatores condicionantes significativos à ocorrência de movimentos de massa, em especial, dos escorregamentos translacionais.Palavras–chave: escorregamentos translacionais, corridas de lama, sistema de informação geográfica, desastre natural.Abstract Mass movements are landscape evolution processes conditioned by geological, geomorphological, hydrological, climatological and land cover factors. Southeastern Brazil is distinguished by the occurrence of catastrophic landslides events, due to the association of land use and physiographic factors which cause high susceptibility to the occurrence of different types of mass movements, mainly translational slides. Although mass movements have an important role in landscape evolution, their occurrence in areas occupied by human activities has generated numerous life human and economic losses. The mountainous region of Rio de Janeiro, in January 2011, was affected by rainstorms that caused the occurrence of extreme magnitude landslide events, which caused destruction and death as well as deep scars in the landscape, which can contribute to the study of mass movements processes. This paper aims to analyse the spatial relationships between the morphology of the slopes, the land cover and the occurrence of mass movements in January 2011 in the mountainous region of Rio de Janeiro. The study was performed in the Roncador river basin, Nova Friburgo municipality, by overlaying the spatial distribution of landslide scars with morphological variables of the slopes and land cover classes. The results show that the scars predominated on steep and concave slopes covered by dense vegetation, which corroborates the literature that indicates the slope and the curvature as a significant conditioning factor to the occurrence of mass movements, in particular, the translational slides.Keywords: translational slides, mudflows, geographic information system, natural disaster.

scholarly journals A GPU-Accelerated Shallow-Water Scheme for Surface Runoff Simulations

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 637 ◽  
Author(s):  
Francesca Aureli ◽  
Federico Prost ◽  
Renato Vacondio ◽  
Susanna Dazzi ◽  
Alessia Ferrari
Keyword(s):  
Shallow Water ◽  
Surface Runoff ◽  
Numerical Scheme ◽  
Source Term ◽  
Management Strategies ◽  
Flood Management ◽  
Water Model ◽  
Economic Losses ◽  
Emergency Plans ◽  
Digital Elevation

The capability of a GPU-parallelized numerical scheme to perform accurate and fast simulations of surface runoff in watersheds, exploiting high-resolution digital elevation models (DEMs), was investigated. The numerical computations were carried out by using an explicit finite volume numerical scheme and adopting a recent type of grid called Block-Uniform Quadtree (BUQ), capable of exploiting the computational power of GPUs with negligible overhead. Moreover, stability and zero mass error were ensured, even in the presence of very shallow water depth, by introducing a proper reconstruction of conserved variables at cell interfaces, a specific formulation of the slope source term and an explicit discretization of the friction source term. The 2D shallow water model was tested against two different literature tests and a real event that recently occurred in Italy for which field data is available. The influence of the spatial resolution adopted in different portions of the domain was also investigated for the last test. The achieved low ratio of simulation to physical times, in some cases less than 1:20, opens new perspectives for flood management strategies. Based on the result of such models, emergency plans can be designed in order to achieve a significant reduction in the economic losses generated by flood events.

Food Submergence Calculation and Analysis Using Digital Elevation Model and Geographical Information System

2014 ◽  
Vol 571-572 ◽  
pp. 792-795
Author(s):  
Xiao Qing Zhang ◽  
Kun Hua Wu
Keyword(s):  
Information System ◽  
Digital Elevation Model ◽  
Flood Control ◽  
Large Scale ◽  
Geographical Information ◽  
Economic Losses ◽  
Model Data ◽  
Digital Elevation ◽  
Elevation Model ◽  
Digital Elevation Model Data

Floods usually cause large-scale loss of human life and wide spread damage to properties. Determining flood zone is the core of flood damage assessment and flood control decision. The aim of this paper is to delineate the flood inundation area and estimate economic losses arising from flood using the digital elevation model data and geographic information system techniques. Flood extent estimation showed that digital elevation model data is very precious to model inundation, however, in order to be spatially explicit flood model, high resolution DEM is necessary. Finally, Analyses for the submergence area calculation accuracy.

scholarly journals Improvement of river network representation in Africa: application of an approach based on digital elevation data and environmental characteristics

2021 ◽  
Vol 384 ◽  
pp. 19-23
Author(s):  
Axel P. Belemtougri ◽  
Agnès Ducharne ◽  
Harouna Karambiri
Keyword(s):  
Environmental Variables ◽  
Drainage Density ◽  
Landscape Characteristics ◽  
Ongoing Work ◽  
Digital Elevation ◽  
Small Streams ◽  
Elevation Data ◽  
Length Width ◽  
Digital Elevation Data ◽  
The Relationship

Abstract. In many continental databases representing rivers across Africa, information on rivers characteristics (length, width, intermittent or perennial) is often incomplete, and small streams are largely underrepresented. Fortunately, the use of topographic information from digital elevation models (DEMs) provides an opportunity to have more detailed information on rivers, particularly small streams in broad areas. A common approach to extract streams from DEM is to consider as a stream all DEM cells that drain at least a certain upstream surface, commonly known as the minimum contributing area (Amin). This parameter (Amin) is generally defined uniformly over large areas and this independently of the very variable climate and landscape conditions so that the generated streams have a rather uniform spatial distribution. To address this issue, using a 3′′ (approx. 90 m × 90 m) DEM of Burkina Faso, the relationship between Amin and the observed drainage density (Ddobs) was established with satisfactory performance (r2=0.86). In ongoing work, the functional relationship between the observed drainage densities (Ddobs) and environmental variables (lithology, climate, geology, vegetation cover) should allow for the establishment of the relationships between Amin and the environmental variables. This relationship allows for spatially variable Amin values depending on landscape characteristics. Before extracting river networks in Africa, the next step will be to validate or update these relationships in several countries.

scholarly journals Analysis of Morphological Features of Sargalu Region in Sulaymaniyah Governorate, North of Iraq, by using Geographic Information System

2021 ◽  
pp. 1164-1176
Author(s):  
Ali Abdul-Jaleel Hussain ◽  
Muaid Jassim Rasheed
Keyword(s):  
Thermal Emission ◽  
Drainage System ◽  
Asymmetry Factor ◽  
Digital Elevation ◽  
The Social ◽  
Structural Disturbance ◽  
Tectonically Active ◽  
Elevation Model ◽  
Geological Formations ◽  
Tectonic Activities

It is an ideal area of research to examine related indicators to anticipate relative tectonic activities, where there is a broad range of geological formations with elements of different sedimentary rocks. This study includes assessing and evaluating the relative tectonic activities within the Sargalu area by using a morphometric approach, which involved the use of different indices that can explain and help understanding the geometry, development level, lithology, and structural disturbance on a sub-basinal level. The research was accomplished by using ArcGIS 10.5 hydrology tools to design the drainage system of each studied stream. The Advanced Spaceborne Thermal Emission Radiometer (ASTER) satellite imagery data and the Digital Elevation Model (DEM 90m) were used. Moreover, Global Mapper and Statistical Package for the Social Sciences (SPSS) were applied. DEM datasets of ASTER were used for watershed delineation. Also, 14 sub-basins were delineated in the Sargalu area. Morphometric indices used include Shape Related Indices, such as Rc, Bs, Rf, Ls, Re, T, and Af. Basin asymmetry factor (Af) and several geomorphic indices were also utilized. Based on the shape related indices (Rc, Rf, Re, Ls, and Cc), the results were found to be similar and, for most sub-basins, had an elongated nature. The elongated basins are connected with tectonically active areas, while the circulated basins are connected with the tectonically undisturbed environment.

scholarly journals Measuring change at Earth’s surface: On-demand vertical and three- dimensional topographic differencing implemented in OpenTopography

Geosphere ◽  
2021 ◽  
Author(s):  
Chelsea Scott ◽  
Minh Phan ◽  
Viswanath Nandigam ◽  
Christopher Crosby ◽  
J Ramon Arrowsmith
Keyword(s):  
Three Dimensional ◽  
Point Clouds ◽  
Data Sets ◽  
Data Set ◽  
Landscape Characteristics ◽  
On Demand ◽  
Digital Elevation ◽  
Rigid Deformation ◽  
Optimal Resolution ◽  
Topography Data

Topographic differencing measures landscape change by comparing multitemporal high-resolution topography data sets. Here, we focused on two types of topographic differencing: (1) Vertical differencing is the subtraction of digital elevation models (DEMs) that span an event of interest. (2) Three-dimensional (3-D) differencing measures surface change by registering point clouds with a rigid deformation. We recently released topo­graphic differencing in OpenTopography where users perform on-demand vertical and 3-D differencing via an online interface. OpenTopography is a U.S. National Science Foundation–funded facility that provides access to topographic data and processing tools. While topographic differencing has been applied in numerous research studies, the lack of standardization, particularly of 3-D differencing, requires the customization of processing for individ­ual data sets and hinders the community’s ability to efficiently perform differencing on the growing archive of topography data. Our paper focuses on streamlined techniques with which to efficiently difference data sets with varying spatial resolution and sensor type (i.e., optical vs. light detection and ranging [lidar]) and over variable landscapes. To optimize on-demand differencing, we considered algorithm choice and displacement resolution. The optimal resolution is controlled by point density, landscape characteristics (e.g., leaf-on vs. leaf-off), and data set quality. We provide processing options derived from metadata that allow users to produce optimal high-quality results, while experienced users can fine tune the parameters to suit their needs. We anticipate that the differencing tool will expand access to this state-of-the-art technology, will be a valuable educational tool, and will serve as a template for differencing the growing number of multitemporal topography data sets.

Digital elevation model-based watershed geomorphic entropy for the study of landscape evolution of a watershed geomorphic system in the loess landforms of China

2016 ◽  
Vol 41 (2) ◽  
pp. 139-153
Author(s):  
Weidong Zhao ◽  
Guoan Tang ◽  
Lei Ma ◽  
Jitang Zhao ◽  
Wan Zhou ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Loess Plateau ◽  
Landscape Evolution ◽  
The Loess Plateau ◽  
Experimental Conditions ◽  
Method Of Calculation ◽  
Sediment Yields ◽  
Digital Elevation ◽  
Elevation Model ◽  
Evolutional Process

Although the concept of entropy in landscape evolution was proposed over 40 years ago, previous studies of geomorphic entropy paid little attention to the applications of geomorphic entropy in the erosional watershed geomorphic system on the Loess Plateau in China. Therefore, we propose a new concept of entropy called watershed geomorphic entropy (WGE) and its method of calculation based on a digital elevation model and the principles of system theory. To study the geomorphic significances of WGE, we applied the WGE to an artificial rainfall experiment that was originally designed to study erosional processes in a small open watershed geomorphic system on the Loess Plateau. Our study shows that the decrease of WGE in an open watershed geomorphic system means a gradual erosional or erosion-dominated landscape evolutional process and the change of WGE shows a perfectly positive linear correlation with the measured sediment yields of the outlet of the watershed system under our experimental conditions. In addition, to some extent, the decrease of the change of WGE also reflects the reduction of total potential energy of a specific erosional, or erosion-dominated, open watershed geomorphic system.

scholarly journals Development of Flood Damage Regression Models by Rainfall Identification Reflecting Landscape Features in Gangwon Province, the Republic of Korea

Land ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 123
Author(s):  
Hyun Il Choi
Keyword(s):  
Regression Models ◽  
Flood Damage ◽  
Linear Functions ◽  
Republic Of Korea ◽  
Economic Losses ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
Landscape Features ◽  
Landscape Characteristics ◽  
Damage Risk

Torrential rainfall events associated with rainstorms and typhoons are the main causes of flood-related economic losses in Gangwon Province, Republic of Korea. The frequency and severity of flood damage have been increasing due to frequent extreme rainfall events as a result of climate change. Rainfall is a major cause of flood damage for the study site, given a strong relationship between the probability of flood damage over the last two decades and the maximum rainfall for 6 and 24 h durations in the 18 administrative districts of Gangwon Province. This study aims to develop flood damage regression models by rainfall identification for use in a simplified and efficient assessment of flood damage risk in ungauged or poorly gauged regions. Optimal simple regression models were selected from four types of non-linear functions with one of five composite predictors averaged for the two rainfall datasets. To identify appropriate predictor rainfall variables indicative of regional landscape features, the relationships between the composite rainfall predictor and landscape characteristics such as district size, topographic features, and urbanization rate were interpreted. The proposed optimal regression models may provide governments and policymakers with an efficient flood damage risk map simply using a regression outcome to design or forecast rainfall data.

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