Добірка наукової літератури з теми "GIS, DTM, Geomorphometry"

Digital terrain model (DTM) is the base for calculation of the surface runoff under the influence of the gravity (gravity flow) in hydrological analysis. It is important to produce hydrologically corrected DTM with the removed natural and artificial depressions to avoid numerical problems in algorithms of the gravity flow. The pit removal procedure changes geomorphometry of the DTM. GIS software packages use pit removal algorithm independently of geomorphmetric features of the analyzed area. In need of minimally modified DTM after the pit removal areas, the carving method (deepen drainage routes) and the filling method (fill sink) were analyzed on three different geomorphometric areas (bare mountain range, hilly wooded area and the plain area intersected with the network of the drainage canals). The recommendation is given for the choice of geomorphometric least changing DTM algorithm. The input data are raster data of elevation points created by stereoscopic photogrammetry method in 5x5 and 25x25 meter resolution. Differences have been noticed during the process of creating raster data. The recommendation is given for the choice of the most acceptable method for each type of area on the basis of comparison of the original elevation points with the elevation points in created DTM.

Digital terrain model (DTM) is the base for calculation of the surface runoff under the influence of the gravity (gravity flow) in hydrological analysis. It is important to produce hydrologically corrected DTM with the removed natural and artificial depressions to avoid numerical problems in algorithms of the gravity flow. The pit removal procedure changes geomorphometry of the DTM. GIS software packages use pit removal algorithm independently of geomorphmetric features of the analyzed area. In need of minimally modified DTM after the pit removal areas, the carving method (deepen drainage routes) and the filling method (fill sink) were analyzed on three different geomorphometric areas (bare mountain range, hilly wooded area and the plain area intersected with the network of the drainage canals). The recommendation is given for the choice of geomorphometric least changing DTM algorithm. The input data are raster data of elevation points created by stereoscopic photogrammetry method in 5x5 and 25x25 meter resolution. Differences have been noticed during the process of creating raster data. The recommendation is given for the choice of the most acceptable method for each type of area on the basis of comparison of the original elevation points with the elevation points in created DTM.

Using the example of the Korshunovsky GOK quarry, the possibilities of processing publicly available SRTM C-SIR and ASTER GDEM DEM data and remote sensing materials obtained from LANDSAT and SENTINEL satellites in the SAGA GIS for specialized mapping of mountainous terrain are considered. The results of constructing derived geomorphometric maps based on DEM are presented. Restrictions on the use of the materials under consideration are justified.

In the present study, an attempt has been made to study the quantitative geomorphological analysis and hydrological characterization of 95 micro-watersheds (MWS) of Baira river watershed in Himachal Pradesh, India with an area of 425.25 Km2. First time in the world, total 173 morphometric parameters have been generated in a single watershed using satellite remote sensing data (i.e. IRS-P6 ResourceSAT-1 LISS-III, LandSAT-7 ETM+, and LandSAT-8 PAN & OLI merge data), digital elevation models (i.e. IRS-P5 CartoSAT-1 DEM, ASTER DEM data), and soI topographical maps of 1: 50,000 scale. The ninety-five micro-watersheds (MWS) of Baira river watershed have been prioritized through the morphometric analysis of different morphometric parameters (i.e. drainage network, basin geometry, drainage texture analysis, and relief characterizes ). The study has concurrently established the importance of geomorphometry as well as the utility of remote sensing and GIS technology for hydrological characterization of the watershed and there for better resource and environmental managements.

This study evaluates the geomorphometric parameters of the topography in Ethiopia using scripting cartographic methods by applying R languages (packages 'tmap' and 'raster') and Generic Mapping Tools (gmt) for 2D and 3D topographic modelling. Data were collected from the open source repositories on geospatial data with high resolution: gebco with 15 arc-second and etopo1 with 1 arc-minute resolution and embedded dataset of srtm 90 m in 'raster' library of R. The study demonstrated application of the programming approaches in cartographic data visualization and mapping for geomorphometric analysis. This included modelling of slope steepness, aspect and hillshade visualized using dem srtm90 to derive geomorphometric parameters of slope, aspect and hillshade of Ethiopia and demonstrate contrasting topography and variability climate setting of Ethiopia. The topography of the country is mapped, including Great Rift Valley, Afar Depression, Ogaden Desert and the most distinctive features of the Ethiopian Highlands. A variety of topographical zones is demonstrated on the presented maps. The results include 6 new maps made using programming console-based approach which is a novel method of cartographic visualization compared to traditional gis software. The most important fragments of the codes are presented and technical explanations are provided. The presented series of 6 new maps contributes to the cartographic data on Ethiopia and presents the methodology of scripting mapping techniques.

O relevo é um dos principais fatores que controlam os processos que ocorrem na superfície terrestre. Dessa forma, a caracterização geomorfométrica é um elemento básico para o planejamento e gestão de bacias hidrográficas. Considerando que a resolução da grade do modelo altimétrico influencia as características topográficas extraídas, este trabalho teve como objetivo quantificar atributos geomorfométricos para a bacia hidrográfica do córrego Guariroba a partir de Modelos Digitais de Superfície (MDSs) baseados em imagens de radar – SRTM e Alos Palsar – e Modelo Digital de Elevação (MDE) gerado por aerofotogrametria, com tamanhos de grade de 30, 12,5 e 5 m, respectivamente, visando demonstrar o efeito da resolução espacial da grade nos parâmetros derivados, bem como subsidiar a escolha do modelo altimétrico apropriado para orientar o planejamento e o gerenciamento dos recursos solo e água nesta bacia hidrográfica. Os parâmetros geomorfométricos foram avaliados sob três perspectivas: rede de drenagem, geometria e características de relevo. A rede de drenagem é do tipo dendrítica; a hierarquia fluvial é de quinta ordem; a forma da bacia é menos alongada; o canal principal tende a ser retilíneo com alta influência da carga sedimentar; e a área possui baixo relevo e declives e é dissecada moderadamente. As bases de menor resolução espacial (MDS 30 e 12,5m) subestimaram as áreas planas (27,0 e 16,1%) e com relevo suave ondulado (4,4 e 29,2%); e superestimaram a área com relevo ondulado (34,9 e 70,9%) e com declive superior a 5% (29,3 e 77,0%), respectivamente. O modelo altimétrico que permitiu melhor delineamento dos parâmetros geomorfométricos foi o gerado a partir do levantamento aerofotogramétrico. Implications of the resolution and source of altimetric models in the quantitative analysis of geomorphometric attributes for the Guariroba watershed, Campo Grande, MS A B S T R A C TRelief is one of the main factors that control the processes that occur on the Earth's surface. Thus, geomorphometric characterization is a basic element for the planning and management of watersheds. The objective of this study was to investigate the impact of Digital Surface Models (DSMs) and Digital Elevation Model (DEM) resolution on the extraction and quantification of geomorphometric attributes for the Guariroba watershed. Elevation data base generated by radar (Alos Palsar and SRTM) and photogrammetry techniques with 30, 12.5 and 5m grid size, were used. The geomorphometric attributes were evaluated from three perspectives: drainage network, geometry, and relief characteristics. The drainage network is of the dendritic type; the river hierarchy, of fifth order; the shape of the basin, less elongated; the main channel, rectilinear with high influence of sedimentary load; and the area, dissected moderately with low relief and slopes. The grids with the lowest spatial resolution (DSM 30 and 12.5m) underestimated the flat areas (27.0 and 16.1%) and those with soft wavy relief (4.4 and 29.2%); and overestimated the areas with wavy relief (34.9 and 70.9%) and those with a slope of more than 5% (29.3 and 77.0%), respectively. The altimetric model which allowed a better determination of the geomorphometric attributes was generated from the aerophotogrammetric survey. The results constitute a baseline database to aid in planning and management of soil and water resources in this watershed.Keywords: Grid size, GIS, Soil and water conservation, Environmental planning.

Abstract. The availability of high resolution Digital Elevation Models (DEM) at a regional scale enables the analysis of topography with high levels of detail. Hence, a DEM-based geomorphometric approach becomes more accurate for detecting potential rockfall sources. Potential rockfall source areas are identified according to the slope angle distribution deduced from high resolution DEM crossed with other information extracted from geological and topographic maps in GIS format. The slope angle distribution can be decomposed in several Gaussian distributions that can be considered as characteristic of morphological units: rock cliffs, steep slopes, footslopes and plains. A terrain is considered as potential rockfall sources when their slope angles lie over an angle threshold, which is defined where the Gaussian distribution of the morphological unit "Rock cliffs" become dominant over the one of "Steep slopes". In addition to this analysis, the cliff outcrops indicated by the topographic maps were added. They contain however "flat areas", so that only the slope angles values above the mode of the Gaussian distribution of the morphological unit "Steep slopes" were considered. An application of this method is presented over the entire Canton of Vaud (3200 km2), Switzerland. The results were compared with rockfall sources observed on the field and orthophotos analysis in order to validate the method. Finally, the influence of the cell size of the DEM is inspected by applying the methodology over six different DEM resolutions.

Abstract. Digital soil mapping applies soil attributes, Remote sensing and Geomorphometrics indices to estimate soil types and properties at unobserved locations. This study carried out in order to comparison two data mining algorithms such as Random Forest (RF) and Boosting Regression tree (BRT) and two features selection principal component analysis (PCA) and variance inflation factor (VIF) for predicting soil taxonomy class at great group and subgroup levels. A total of 61 soil profile observation based on stratified random determined and digged in area with approximately 16660 hectares.19 RS indices and geomorphometrics covariates derivated from Landsate-8 imagery and DEM with 30 meters’ resolution in ERDAS IMAGINE 2014 and SAGA GIS version 7.0 software’s. Also to run four Data mining algorithms scenarios (PCA-RF, VIF-RF, PCA-BRT, VIF-BRT) from “Randomforest” and “C.5” packages were used in R studio software. 80% and 20% from soil profiles were applied for calibrating and validating. The results showed that in PCA and VIF approaches, eight covariates such as (Relative slope position, diffuse insolation, modified catchment, normalized height, RVI, Standard height, TWI, Valley depth) and six covariates (NDVI, DVI, Catchment area, DEM, Salinity index, Standard height) were selected. The validation results based on overall accuracy and kappa index for scenarios at great group level indicated that 88,93,62, 54 and 75,83,51,45 percentages and for subgroup level had 70, 77, 54, 47 and 60, 71, 43, 37 percentages, respectively. Generally, VIF-RF had accuracy rather than from other scenarios at two categorical level in this study area.

Check dams are widely used watershed management measures for reducing flood peak discharge and sediment transport, and increasing lag time and groundwater recharge throughout the world. However, identifying the best suitable sites for check dams within the stream networks of various watersheds remains challenging. This study aimed to develop an open-source software with user-friendly interface for screening the stream network possibilities and identifying and guiding the selection of suitable sites for check dams within watersheds. In this developed site selection software (SSS), multi-criteria decision analysis (MCDA) was integrated into geographic information systems (GIS), which allowed for numerous spatial data of the multiple criteria to be relatively simply and visually processed. Different geomorphometric and topo-hydrological factors were considered and accounted for to enhance the SSS identification of the best locations for check dams. The factors included topographic wetness index (TWI), terrain ruggedness index (TRI), topographic position index (TPI), sediment transport index (STI), stream power index (SPI), slope, drainage density (DD), and stream order (SO). The site identification performance of the SSS was assessed using the receiver operating characteristic (ROC) curve method, with results for the case study example of the Poldokhtar watershed in Iran showing excellent performance and identifying 327 potential sites for efficient check dam construction in this watershed. The SSS tool is not site-specific but is rather general, adaptive, and comprehensive, such that it can and should be further applied and tested across different watersheds and parts of the world.

The article is devoted to the structural and morphometric analysis of a small rivers using the example of the Ihe-Ukhgun river basin (left tributary of the Irkut river), which is based on a complex processing of a digital elevation model (DEM). The author has prepared a hydrologically correct DEM based on the ALOS Digital Surface Model (DSM) satellite data, carried out an automated calculation and mapping of the basin erosion network based on the DEM data, calculated the structural indicators of the third-order basins for analyzing the basin organization of the small rivers network. Structural and morphometric analysis using GIS was practically not used for the Ihe-Ukhgun river basin which is placed in different landscapes, geological and geomorphological conditions. The work is based on geomorphometric and structural morphometric methods as well as the method of geoinformation mapping and relief modeling for analyzing lower-order basins. Thalweg erosion network modeling up to the fourth order of the river basin Ihe-Uhgun was carried out with using of DEM analysis in the ArcGIS 10 program. The map of the erosional network of the basin was constructed, morphometric indicators of rivers (length, area of basins, sum of slopes, coefficient of basin asymmetry, etc.) were obtained, and then the indices of the basin structure (structure of bifurcation, lengths, areas and slopes) were calculated. As a result, an asymmetric erosion network was revealed, which indicates a great work in the transfer of matter of first-order streams. First-order streams exceed those of the second and third orders streams in terms of catchment area, length and steepness of adjacent slopes. The interrelation of morphometric characteristics of different-order streams within third order sub-basins are most fully traced with the using of structural indices and their comparison with modal indicators. In general, the Ihe-Ukhgun river basin is characterized by a heterogeneous structure of the streams ratio of the first, second and third orders. The basins of the Khurguta, Khubyty and Ulan-Gol rivers have the highest degree of homogeneity. At the same time, for the Ihe-Ukhgun river basin, there is no direct relationship with the area of the third order drainage basins.

Terrain attributes computed from Digital Elevation Models (DEMs) are widely used in hydrology and hydrologic modeling. It is important to consider that the values of the attributes can be different depending on the resolution of the DEM from which they are derived. The question arises as to how much exactly the high-resolution DEMs created through LIDAR remote sensing techniques change the values of the terrain attributes when compared to lower resolution DEMs.In this thesis a LIDAR-derived DEM of 20 feet resolution was resampled using a nearest-neighbour algorithm to various coarser resolutions to examine and quantify the effect of DEM resolution upon a series of hydrologically significant terrain attributes including slope, surface curvature, topographic wetness index, stream power index and stream networks. Values for slope and surface curvature are found to be smaller when computed from lower resolution DEMs; values for the topographic wetness index and stream power index are found to increase as DEM cell size increases.The derived stream networks for each resolution were compared in terms of length per stream order, drainage density, bifurcation ratio, and overall accuracy indicating a loss of small detail, but only a modest change in the overall stream network morphometry. This research suggests that it is possible to establish relationships that quantify the effects of DEM resolution upon hydrologically significant terrain attributes, which can then be considered when processing DEMs from various resolutions for the purpose of parameterizing hydrologic models.