scholarly journals Free Global DEMs and Flood Modelling—A Comparison Analysis for the January 2015 Flooding Event in Mocuba City (Mozambique)

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 176
Author(s):  
Julio Garrote
Keyword(s):  
Developing Countries ◽  
Data Acquisition ◽  
Field Data ◽  
Flood Hazard ◽  
Hazard Analysis ◽  
Control Point ◽  
Alos Palsar ◽  
Aster Gdem ◽  
Digital Elevation ◽  
Flooding Event

Flood hazard and risk analysis in developing countries is a difficult task due to the absence or scarce availability of flow data and digital elevation models (DEMs) with the necessary quality. Up to eight DEMs (ALOS Palsar, Aster GDEM, Bare Earth DEM, SRTM DEM, Merit DEM, TanDEM-X DEM, NASA DEM, and Copernicus DEM) of different data acquisition, spatial resolution, and data processing were used to reconstruct the January 2015 flood event. The systematic flow rate record from the Mocuba city gauge station as well as international aid organisms and field data were used to define both the return period peak flows in years for different flood frequencies (Tyear) and the January 2015 flooding event peak flow. Both visual and statistical analysis of flow depth values at control point locations give us a measure of the different hydraulic modelling performance. The results related to the Copernicus DEM, both in visual and statistical approach, show a clear improvement over the results of the other free global DEMs. Under the assumption that Copernicus DEM provides the best results, a flood hazard analysis was carried out, its results being in agreement with previous data of the effects of the January 2015 flooding event in the Mocuba District. All these results highlight the step forward that Copernicus DEM represents for flood hazard analysis in developing countries, along with the use of so-called “citizen science” in the form of flooding evidence field data acquisition.

scholarly journals Comparison of Digital Elevation Models for Determining the Area and Volume of the Water Reservoir

2021 ◽  
pp. 37-45
Author(s):  
M. Bakiev ◽  
K. Khasanov
Keyword(s):  
Mean Squared Error ◽  
Control Point ◽  
Water Reservoir ◽  
Longitudinal Profile ◽  
Topographic Map ◽  
Alos Palsar ◽  
Aster Gdem ◽  
Digital Elevation ◽  
Longitudinal Profiles ◽  
Area And Volume

Nowadays, like many other fields, DEM is widely used in the field of hydraulic engineering. In our studies, we compared the DEMs (SRTM, ASTER GDEM v2, and ALOS PALSAR) for the area recommended for the construction of the Shurbulak water reservoir. Contours were developed for all DEMs and were compared with the contours of a topographic map. The contours of the SRTM and ALOS PALSAR closely match with the contours on the topographic map than ASTER. Vertical differences between SRTM, ASTER GDEM2, and ALOS PALSAR products were computed the root mean squared error (RMSE) compared to Ground Control Point (GCP) data. RMSE results show that 3.53 m for ALOS PALSAR, 6.27 m for ASTER and 4.09 m for SRTM. The longitudinal profiles of dams (No. 1 and No. 2) of all DEMs were compared with the data of the design institute - UzGIP. The results of comparing the longitudinal profile of the dam (No. 1 and No. 2) on digital ALOS PALSAR models correspond to the longitudinal profile of dams (No. 1 and No. 2) developed by the design institutes. Viewed as a result of all comparisons (comparison of DEMs and topographic map, computed RMSE, comparison longitudinal profile of the dam) ALOS PALSAR is more accurate than other DEMs. Therefore, we decided to use ALOS PALSAR for the determination of water reservoir area and volume. The area and volume of the reservoir were determined using the digital model ALOS PALSAR.

Quality Assessment of Globally Available Digital Elevation Model (DEM) for Mountainous Region

2021 ◽  
Vol 5 (1) ◽  
pp. 11-21
Author(s):  
Sangay Gyeltshen ◽  
Krisha Kumar Subedi ◽  
Laylo Zaridinova Kamoliddinovna ◽  
Jigme Tenzin
Keyword(s):  
Digital Elevation Model ◽  
Vertical Displacement ◽  
Satellite System ◽  
Topographic Map ◽  
Alos Palsar ◽  
Aster Gdem ◽  
Digital Elevation ◽  
The Government ◽  
Elevation Model ◽  
The Individual

The study assessed the accuracies of globally available Digital Elevation Models (DEM’s) i.e., SRTM v3, ASTER GDEM v2 and ALOS PALSAR DEM with respect to Topo-DEM derived from topographic map of 5m contour interval. 100 ground control points of the elevation data were collected with the help of kinematic hand held GNSS (Global Navigation Satellite System), randomly distributed over the study area. The widely used RMSE statistic, NCC correlation and sub-pixel-based approach were applied to evaluate the erroneous, correlation, horizontal and vertical displacement in terms of pixels for the individual Digital Elevation Model. Following these evaluations, SRTM DEM was found to be highly accurate in terms of RMSE and displacement compared to other DEMs. This study is intended to provide the researchers, GIS specialists and the government agencies dealing with remote sensing and GIS, a basic clue on accuracy of the DEMs so that the best model can be selected for application on various purposes of the similar region.

scholarly journals Spatial Modeling of Flood Sea Tides (Case Study: East Coast Semarang)

2004 ◽  
Vol 18 (1) ◽  
Author(s):  
Muhammad Aris Marfai
Keyword(s):  
Open Space ◽  
Flood Hazard ◽  
Hazard Analysis ◽  
Spatial Modelling ◽  
Flood Level ◽  
Digital Elevation ◽  
Elevation Model ◽  
Gis Software ◽  
The Impact

The aims of this research are 1) to construct a spatial model of tidal flood hazard, 2) to do hazard analysis of tidal flood. Spatial modelling has been generated using Geographic Information System (GIS) software and ILWIS software was seleccted to do the model operation. Neighborhood function and digital elevation model (DEM) have been applied on the modelling calculation process. DEM data was correted and menipulated using map calculation on the digital form. Tidal flood hazard analysis has been done by means of map calulation on the tidal flood hazard map and detail landuse map. Histogram and tabulation from the result of the map calculation have been analyzed to identify the impact of the tidal flood hazard on the landuse. The highest impact of the tidal flood hazard occurs on the 1 meter of tidal flood level, where in the inundation occurs mainly on the fishpond and yard/ open space area.

scholarly journals Comparison of Digital Elevation Models for the designing water reservoirs: a case study Pskom water reservoir

2021 ◽  
Vol 264 ◽  
pp. 03058
Author(s):  
Khojiakbar Khasanov ◽  
Azamat Ahmedov
Keyword(s):  
Water Reservoir ◽  
Vertical Axis ◽  
Ground Control ◽  
Control Points ◽  
Alos Palsar ◽  
Aster Gdem ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Vertical Accuracy

This study investigates the accuracy of various DEMs (SRTM DEM, ASTER GDEM, and ALOS PALSAR DEM) for the area of the designing Pskom water reservoir (recommended to construction in Pskom River, in Tashkent region. DEMs are compared for the study area using the Global Mapper application and selection Ground Control Points (GCP). The RMSE we calculate is the most easily interpreted statistic as the square root of the mean square error because it has the same units as the quantity drawn on the vertical axis. Results show that SRTM based measurements of ground control points (GCPs) exhibit RMSE of 15.72 m while ASTER DEM based measurements exhibits and RMSE of 18.47 m, ALOS PALSAR exhibit RMSE of 14.02 m for the Water reservoir located in the plain. There are AOS PALSAR outperforms SRTM and ASTER DEM in detecting vertical accuracy. Based on the capabilities of the Global Mapper program, we can build the longitudinal profile of the approximate location where the dam can be built in each DEM and compare. The results obtained show that the dam height is 187 m at ALOS PALSAR DEM, 168 m at ASTER GDEM, and 175 m at SRTM. The study found that using ALOS PALSAR data in the design of the proposed Pskom Reservoir for construction leads to a more accurate result. Comparing the DEMs data shows that there is more difference between the vertical accuracy; the horizontal accuracy level is almost the same. The results were obtained using ALOS PALSAR data in determining the storage volume (W=479368568 m3) and area (F=8.31 sq., km) of the water reservoir.

scholarly journals Improving remote sensing flood assessment using volunteered geographical data

2013 ◽  
Vol 13 (3) ◽  
pp. 669-677 ◽  
Author(s):  
E. Schnebele ◽  
G. Cervone
Keyword(s):  
Remote Sensing ◽  
Flood Hazard ◽  
Hazard Maps ◽  
Geographical Data ◽  
Machine Learning Classification ◽  
Digital Elevation ◽  
Flooding Event ◽  
Elevation Model ◽  
Flooded Areas

Abstract. A new methodology for the generation of flood hazard maps is presented fusing remote sensing and volunteered geographical data. Water pixels are identified utilizing a machine learning classification of two Landsat remote sensing scenes, acquired before and during the flooding event as well as a digital elevation model paired with river gage data. A statistical model computes the probability of flooded areas as a function of the number of adjacent pixels classified as water. Volunteered data obtained through Google news, videos and photos are added to modify the contour regions. It is shown that even a small amount of volunteered ground data can dramatically improve results.

scholarly journals Assessment of Vertical Accuracy for TanDEM-X 90 m DEMs in Plain, Moderate, and Rugged Terrain

Proceedings ◽  
2019 ◽  
Vol 24 (1) ◽  
pp. 8 ◽  
Author(s):  
Ashutosh Bhardwaj
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Sar Interferometry ◽  
Land Use Land Cover ◽  
Differential Gps ◽  
Alos Palsar ◽  
Aster Gdem ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Topographic Characteristics

Synthetic Aperture Radar (SAR) interferometry technique generates digital elevation models (DEMs) and is used by various agencies widely. The recently released TanDEM-X DEM by DLR at 90 m spatial resolution is available for free download to users. This paper examines the accuracy of TanDEM-X DEM at different experimental sites with different topographic characteristics. Three sites were chosen, namely Kendrapara (Odisha), Jaipur (Rajasthan), and Dehradun (Uttarakhand) with plain, moderate, and highly undulating terrain conditions. The root mean square error (RMSE) were calculated using ground control points (GCPs) collected by differential GPS method for experimental sites at Dehradun, Jaipur, and Kendrapara. The accuracy of TanDEM-X 90 m datasets is compared with other openly accessible optically-derived DEMs (ASTER GDEM V2, CartoDEM V3 R1, AW3D30) and InSAR-derived DEMs (SRTM, ALOS PALSAR RTC HR). The RMSEs reveal that at Jaipur site with moderate terrain with urban and agriculture as major land use land cover (LULC) classes, the results of TanDEM-X 90 m DEM have higher accuracy than ALOS PALSAR RTC HR DEM. However, it is observed that in a predominantly plain region with agriculture practice (Kendrapara site, Odisha) and rugged region (Dehradun site, Uttarakhand) with mixed land use land cover (LULC) (e.g., forest, urban, streams, and agriculture) the results of ALOS PALSAR RTC HR data have higher accuracy than TanDEM-X 90 m DEM. Further, the study indicates that for a relatively plain site at Kendrapara (Orissa), CartoDEM V3 R1 DEM has the best performance with an RMSE of 1.96 m, which is the lowest among all DEMs utilized in the study.

scholarly journals Evaluación de peligro por inundación en Xalapa Veracruz.

UVserva ◽  
2020 ◽  
pp. 289-301
Author(s):  
Carlos Manuel Welsh Rodriguez ◽  
Selene Janitzio Pérez Córdova
Keyword(s):  
Developing Countries ◽  
Flood Hazard ◽  
Digital Elevation Models ◽  
Essential Elements ◽  
Monitoring Data ◽  
Hydrological Models ◽  
Hazard Maps ◽  
Digital Elevation ◽  
The Face ◽  
Flood Hazard Maps

Información de datos físicos espaciales, hidrológicos, meteorológicos y económicos a escalas grandes y actualizados. Son elementos esenciales para generar una buena gestión ante las inundaciones, puesto que la ocurrencia y sus afectaciones han aumentado a nivel mundial, pero lamentablemente con mayor frecuencia en países en vías desarrollo ya que se carece de datos de monitoreo e información actualizada para caracterizar el peligro. Este documento presenta una evaluación de las inundaciones en Xalapa, Veracruz. Aplicando una metodología para desarrollar mapas de peligro de inundación con modelos hidrológicos y Modelos Digitales de Elevación (MDE) a nivel Agebs en las colonias con mayor recurrencia.Palabras clave:Inundaciones; peligro y desastres. AbstractInformation on spatial, hydrological, meteorological and economic physical data at large and updated scales. These are essential elements to generate good management in the face of floods, since the occurrence and its effects have increased globally, but unfortunately more often in developing countries, since there is a lack of monitoring data and updated information to characterize the danger. This document presents an evaluation of the floods in Xalapa, Veracruz. Applying a methodology to develop flood hazard maps with hydrological models and Digital Elevation Models (MDE) at the Agebs level in the colonies with the highest recurrenceKeywords: Floods; Hazard and Disasters.

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