scholarly journals Derivation of Geodesic Flow Fields and Spectrum in Digital Topographic Basins

2008 ◽  
Vol 2008 ◽  
pp. 1-26 ◽  
Author(s):  
Sin Liang Lim ◽  
B. S. Daya Sagar
Keyword(s):  
Flow Field ◽  
Travel Time ◽  
Geodesic Flow ◽  
Digital Elevation Models ◽  
Flow Fields ◽  
Basic Flow ◽  
Digital Form ◽  
Digital Elevation ◽  
Morphology Characterization

We present a framework to characterize terrestrial functions—surficial and bottom topographic regions that are represented, respectively, as raster digital elevation models (DEMs) and digital bathymetric models (DBMs)—through analysis of flow fields that are simulated via geodesic morphology. Characterization of such functions is done via a new descriptor. Computation of this new descriptor involves the following steps: (i) basin in digital form representing topographic fluctuations as an input, (ii) threshold decomposition of basin—that consists of channelized and nonchannelized regions—into sets, (iii) proper indexing of these sets to decide the marker set(s) and its (their) corresponding mask set(s), (iv) performing geodesic propagation that provides basic flow field structures, and (v) finally providing a new basin descriptor—geodesic spectrum. We demonstrated this five-step framework on five different synthetic and/or realistic DEMs and/or DBMs. This study provides potentially invaluable insights to further study the travel-time flood propagation within basins of both fluvial and tidal systems.

scholarly journals Comparison between hydrographically conditioned digital elevation models in the morphometric charaterization of watersheds

2012 ◽  
Vol 32 (5) ◽  
pp. 932-943 ◽  
Author(s):  
Hugo A. S. Guedes ◽  
Demetrius D. da Silva
Keyword(s):  
Near Infrared ◽  
Thermal Emission ◽  
Digital Elevation Models ◽  
Remote Sensing Data ◽  
Shuttle Radar Topography Mission ◽  
Geographical Information ◽  
Data Sets ◽  
Digital Elevation

The aim of this study was to compare the hydrographically conditioned digital elevation models (HCDEMs) generated from data of VNIR (Visible Near Infrared) sensor of ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer), of SRTM (Shuttle Radar Topography Mission) and topographical maps from IBGE in a scale of 1:50,000, processed in the Geographical Information System (GIS), aiming the morphometric characterization of watersheds. It was taken as basis the Sub-basin of São Bartolomeu River, obtaining morphometric characteristics from HCDEMs. Root Mean Square Error (RMSE) and cross validation were the statistics indexes used to evaluate the quality of HCDEMs. The percentage differences in the morphometric parameters obtained from these three different data sets were less than 10%, except for the mean slope (21%). In general, it was observed a good agreement between HCDEMs generated from remote sensing data and IBGE maps. The result of HCDEM ASTER was slightly higher than that from HCDEM SRTM. The HCDEM ASTER was more accurate than the HCDEM SRTM in basins with high altitudes and rugged terrain, by presenting frequency altimetry nearest to HCDEM IBGE, considered standard in this study.

scholarly journals Caracterização Morfométrica e Uso e Ocupação do Solo em Bacia Hidrográfica do Semiárido Pernambucano

2021 ◽  
Vol 14 (2) ◽  
pp. 1036
Author(s):  
Antonio Genessis Bezerra dos Santos ◽  
Alan Cezar Bezerra ◽  
Antônio Henrique Cardoso do Nascimento ◽  
Luciana Sandra Bastos de Souza ◽  
Jhonn Lennon Bezerra da Silva ◽  
...  
Keyword(s):  
Land Use ◽  
Water Resources ◽  
Digital Elevation Models ◽  
Terrain Analysis ◽  
Drought Period ◽  
Digital Elevation ◽  
Caatinga Biome ◽  
Reservoir Watershed ◽  
Morphometric Characterization

Este trabalho investigou  a caracterização de uma bacia hidrográfica do Semiárido de Pernambuco e os efeitos da estiagem nas condições de uso e ocupação do solo por meio da adoção de geotecnologias aplicadas à gestão dos recursos hídricos. Para tanto, foram obtidas as imagens de altimetria pela Embrapa e realizada análise para caracterização morfométrica com o software QGIS e a extensão Terrain Analysis Using Digital Elevation Models – TauDEM. Além disso, se utilizaram as imagens de uso e ocupação do solo da plataforma do MAPBIOMAS BRASIL referente aos anos de 2011 e 2018 para analisar as modificações ocorridas durante o período de estiagem. A Bacia Hidrográfica do açude Cachoeira II apresenta forma alongada, o que indica uma baixa tendência a enchentes em condições normais de precipitação, baixa sinuosidade ocasionando uma maior velocidade de escoamento da água até o exutório e apresenta predominância das seguintes classes de relevo: suave ondulado e ondulado. Os dados de uso e ocupação demostraram que a maior ocupação da bacia é de formação do bioma Caatinga. A estiagem no período de 2012 a 2017 junto com a diminuição das áreas de caatinga e o aumento das áreas de pastagem favoreceram a ocorrência de erosão e o transporte de sedimentos na bacia, contribuindo para diminuição do açude Cachoeira II. Morphometric characterization and land use and occupation in a watershed in the semiarid of Pernambuco ABSTRACTThis work investigated the characterization of a watershed in the Semiarid of Pernambuco and the effects of the drought on the conditions of use and occupation of the soil through the adoption of geotechnologies applied to the management of water resources. For that, the altimetry images were obtained by Embrapa and an analysis for morphometric characterization was performed with the QGIS software and the Terrain Analysis Using Digital Elevation Models - TauDEM extension. In addition, the images of land use and occupation on the MAPBIOMAS BRASIL platform for the years 2011 and 2018 were used to analyze the changes that occurred during the drought period. The Cachoeira II reservoir watershed has an elongated shape, which indicates a low tendency to flooding under normal precipitation conditions, low sinuosity causing a faster flow of water to the exutory and presents predominance of the following relief classes: smooth undulating and wavy. The use and occupation data showed that the largest occupation of the basin is the formation of the Caatinga biome. The drought in the period from 2012 to 2017 together with the decrease in the caatinga areas and the increase in the pasture areas favored the occurrence of erosion and the transport of sediments in the basin, contributing to the decrease of the Cachoeira II reservoir.Keywords: MAPBIOMAS, QGIS, SRTM

A fast topographic characterization of seismic station locations in Iran through integrated use of digital elevation models and GIS

2015 ◽  
Vol 19 (4) ◽  
pp. 949-967 ◽  
Author(s):  
Sadra Karimzadeh ◽  
Masakatsu Miyajima ◽  
Batoul Kamel ◽  
Vera Pessina
Keyword(s):  
Seismic Station ◽  
Digital Elevation Models ◽  
Digital Elevation

scholarly journals Brief communication: Rapid machine-learning-based extraction and measurement of ice wedge polygons in high-resolution digital elevation models

2019 ◽  
Vol 13 (1) ◽  
pp. 237-245 ◽  
Author(s):  
Charles J. Abolt ◽  
Michael H. Young ◽  
Adam L. Atchley ◽  
Cathy J. Wilson
Keyword(s):  
High Resolution ◽  
Digital Elevation Models ◽  
Robust Performance ◽  
Network Geometry ◽  
Fast Training ◽  
Digital Elevation ◽  
Ice Wedge ◽  
Study Sites ◽  
Prudhoe Bay

Abstract. We present a workflow for the rapid delineation and microtopographic characterization of ice wedge polygons within high-resolution digital elevation models. At the core of the workflow is a convolutional neural network used to detect pixels representing polygon boundaries. A watershed transformation is subsequently used to segment imagery into discrete polygons. Fast training times (<5 min) permit an iterative approach to improving skill as the routine is applied across broad landscapes. Results from study sites near Utqiaġvik (formerly Barrow) and Prudhoe Bay, Alaska, demonstrate robust performance in diverse tundra settings, with manual validations demonstrating 70–96 % accuracy by area at the kilometer scale. The methodology permits precise, spatially extensive measurements of polygonal microtopography and trough network geometry.

scholarly journals Assessment of digital elevation models to obtain morphometric characteristics in relief transition region

2019 ◽  
Vol 14 (1) ◽  
pp. 1
Author(s):  
Kevin Nunes Ficher ◽  
Donizete Dos Reis Pereira ◽  
Josiane Silva Oliveira ◽  
André Quintão de Almeida ◽  
Eduardo Morgan Uliana
Keyword(s):  
Digital Elevation Models ◽  
Original Data ◽  
Drainage Area ◽  
Topographic Maps ◽  
Transitional Region ◽  
Morphometric Characteristics ◽  
Main River ◽  
Digital Elevation ◽  
Morphometric Characterization

The purpose of this study was to evaluate the performance of Digital Elevation Models (DEMs) in the morphometric characterization of a basin located in a transitional region between the São Francisco Plateau, São Francisco Depression and Espinhaço Range reliefs. For the study, four DEMs were generated by interpolation of the SRTM data and topographic maps, using the Topo To Raster interpolator with and without mapped hydrography support, available in ArcGIS® 9.3 software. Another DEM was obtained from the SRTM original data. From the generated DEMs, the morphometric characteristics of the basin were determined and compared to those obtained from topographic maps, denominated reference (REF), by means of percentage errors. The evaluation was also performed in a qualitative way, comparing the drainage and the basin delineations. In general, the DEMs obtained with the support of the mapped hydrography (SRTM-TRH and CT-TRH) provided the best results, with small errors, mainly for the main morphometric characteristics of the basin, drainage area and main river length, which ranged from 0.38 to 1.12% and 5.28 to 7.07%, respectively. On the other hand, the DEMs generated without the support of the mapped hydrography (SRTM-O, SRTM-TR and CT-TR) presented major errors mainly in determining the drainage area and length of the main river, which varied from 18.1 to 26.6% and 26.7 to 34.4%, respectively. These occurred due to a deviation of the main river in the São Franciscana Depression region, which allows us to conclude on the necessity and importance of evaluating DEMs before their use.

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