scholarly journals Análise de Risco de Degradação na Bacia Hidrográfica do Riacho do Pontal - PE (Risk Analysis of Degradation in Basin River Pontal – PE)

2012 ◽  
Vol 5 (3) ◽  
pp. 646
Author(s):  
Madson Tavares Silva ◽  
Vicente De P. R. da Silva ◽  
Edicarlos P. de Sousa ◽  
Sonaly D. de Oliveira
Keyword(s):  
Risk Analysis ◽  
Drainage Density ◽  
Morphometric Parameters ◽  
Automatic Process ◽  
Drainage Network ◽  
Low Density ◽  
Gis And Remote Sensing ◽  
Digital Elevation ◽  
Elevation Model ◽  
Low Density Area

Este trabalho teve como objetivo analisar o risco de degradação presente na bacia hidrográfica do Riacho do Pontal-PE, a partir de técnicas de geoprocessamento e sensoriamento remoto da superfície. Parâmetros morfométricos da bacia de drenagem foram obtidos pelo MDE (Modelo Digital de Elevação) utilizando um processo automático através de técnicas de geoprocessamento utilizando o software ARCGIS 9.3. Os resultados demonstraram que a bacia do Riacho do Pontal possui uma área total de 6057,0 km² e perímetro de 464,0 km, a rede de drenagem é de 5ª ordem sendo moderadamente ramificada apresentando um comprimento total de 2060,0 km com um curso principal de 147,6 km, a bacia apresentou uma forma mais alongada, com densidade de drenagem inferior a 0,4 km/km2 assim como baixa densidade hidrográfica, a classe de declividade predominante é do tipo várzea e plano a suave ondulado representado cerca de 90% da área total da bacia. As classes de cobertura de solos predominantes (caatinga densa, caatinga densa degradada e cultivos diversificados) ocupam 5480 km2, área correspondente a 90,4%. As maiores áreas produtoras de sedimento encontram-se próximas a rede de drenagem.Palavras - chave: Rede de Drenagem, Modelo digital de elevação, geoprocessamento. Risk Analysis of Degradation in Basin River Pontal – PE ABSTRACTThis study aimed to analyze the risk of degradation in the watershed of this Pontal-PE stream, from techniques of GIS and remote sensing surface. Morphometric parameters of the watershed were obtained by DEM (Digital Elevation Model) using an automatic process through geoprocessing techniques using software ARCGIS 9.3. The results showed that the Pontal stream basin has a total area of ​​6057,0 km2 and a perimeter of 464,0 km, the drainage network is 5th order being moderately branched having a total length of 2060,0 km with a course main 147,6 km, the basin had a more elongated form, with drainage density less than 0.4 km/km2 well as low-density area, the class of slope is predominantly lowland type and plan the gentle undulating represented about 90% of the total area of the basin. The classes of predominant land cover (caatinga densa, caatinga densa degradada e cultivos diversificados) occupy 5,480 km2, the area corresponding to 90,4%. The major sediment-producing areas are near the drainage network.Keywords: Drainage network, elevation digital model, geoprocessing.

scholarly journals Morphometric analysis and watershed prioritization in relation to soil erosion in Dudhnai Watershed

2021 ◽  
Vol 11 (9) ◽  
Author(s):  
W. R. Singh ◽  
S. Barman ◽  
G. Tirkey
Keyword(s):  
Soil Erosion ◽  
Water Conservation ◽  
High Surface ◽  
Drainage Density ◽  
Morphometric Parameters ◽  
Geographical Information ◽  
Gis And Remote Sensing ◽  
Digital Elevation ◽  
Elevation Model

AbstractMorphologic parameters of a watershed could help in segregating critical sub-watersheds for taking up conservation practices and mitigation interventions. Determination of critical watersheds or prioritization of sub-watersheds is inevitable for efficient and sustainable watershed management programs and allocation of its natural resources. The traditional methods of determination of morphologic parameters are time consuming, expensive and requires huge labor. However, the process becomes easier, cheaper and faster with the advent of Geographical Information System (GIS) and remote sensing technologies. In the present study, a combined approach of using toposheet, remotely sensed digital elevation model and morphometric ArcGIS toolbox has been adopted to determine morphometric parameters in Dudhnai river basin, a sub-basin of river Brahmaputra which is prone to both erosion and sedimentation. Seven sub-watersheds of Dudhnai have been prioritized by using the morphometric parameters and ranked them according to its vulnerability to soil erosion. The results of bifurcation ratio, drainage density, drainage intensity and constant of channel maintenance showed that Dudhnai watershed is a well-dissected watershed with less risk to flooding and soil erosion. However, significantly high values of infiltration number and ruggedness number obtained are indicative of very low infiltration which may result in high surface runoff and soil erosion. The study also revealed that channel erosion is stronger than sheet erosion in the basin. The prioritization of the sub-watersheds implied that Chil sub-watershed is the most susceptible sub-watershed that needs greater attention for soil and water conservation measures. The results of the present study could aid various stakeholders who are involved in the watershed development and management programs.

scholarly journals Morphometric analysis of the drainage network in the Vitosha Mountain (preliminary results)

2021 ◽  
Vol 82 (3) ◽  
pp. 210-212
Author(s):  
Petko Bozhkov
Keyword(s):  
Morphometric Analysis ◽  
Drainage Density ◽  
Morphometric Parameters ◽  
Topographic Maps ◽  
Drainage Network ◽  
Stream Length ◽  
Digital Elevation ◽  
Elevation Model ◽  
Channel Segment

The aim of the following case study is to analyze quantitatively the drainage network in the Vitosha Mountain, SW Bulgaria. Drainage network is outlined from topographic maps and extracted from digital elevation model (DEM). Several morphometric parameters are calculated – drainage density, channel-segment frequency, total stream length, etc. Hierarchy of tributaries and main rivers is also discussed.

scholarly journals Extração Automática de Drenagem: uma Análise Comparativa a Partir de Diferentes Ferramentas e Bases de Dados (Draining automatic extraction: a comparative analysis of different from the tools and databases )

2016 ◽  
Vol 9 (6) ◽  
pp. 1849
Author(s):  
Reurysson Chagas de Sousa Morais ◽  
Marta Celina Linhares Sales
Keyword(s):  
Large Scale ◽  
River Basins ◽  
Morphometric Parameters ◽  
Topographic Mapping ◽  
Automatic Extraction ◽  
Drainage Network ◽  
Computational Tools ◽  
Digital Elevation ◽  
Elevation Model ◽  
Manual Correction

A necessidade de planejamento e gerenciamento de bacias hidrográficas tem incitado pesquisa que buscam compreender sua dinâmica hidrológica. Em regiões que apresentam carência de mapeamento topográfico em grande escala, é comum o uso de modelos digitais de elevação (MDE) para extração automática da rede de drenagem, delimitação de bacias hidrográficas e obtenção de parâmetros hidrográficos e morfométricos. Diante deste cenário o presente trabalho teve como objetivo avaliar a eficiência de duas ferramentas computacionais (Hydrology e TauDEM) e três bases de dados (SRTM, AGEDM e AW3D) para a extração de rede de drenagem e cálculo de parâmetros hidrográficos. Concluiu-se que o software TauDEM representa a melhor solução da extração de drenagem, pois minimiza a geração de drenagem retilínea e paralela em áreas de relevo plano. Dentre as bases de dados, a drenagem extraída dos dados AW3D apresentaram maior correspondência com drenagem de referência do IBGE. De modo geral, os parâmetros morfométricos calculados para a Bacia Hidrográfica do Alto Gurguéia (BHAG), a partir das três bases de dados selecionadas, não apresentaram diferenças significativas, indicando o potencial das ferramentas e bases de dados para análises hidrográficas de médias e grandes bacias. Em todo caso, recomenda-se a inspeção e correção manual da rede de drenagem ao aplicar qualquer método de extração automática, com o intuito de reduzir os erros decorrentes das limitações dos softwares.   A B S T R A C T The need for planning and management of river basins has prompted research that seek to understand their hydrological dynamics. In regions with lack of topographic mapping on a large scale, it is common to use digital elevation models (DEM) for automatic drainage network extraction, delineation of watersheds and obtain hydrographic and morphometric parameters. Against this background the present study aimed to evaluate the efficiency of two computational tools (Hydrology and TauDEM) and three databases (SRTM, AGEDM and AW3D) for drainage network extraction and calculation of hydrographic parameters. It was concluded that the TauDEM software is the best solution drain extraction, because it minimizes the generation of rectilinear and parallel drainage in flat terrain areas. Among those databases, the drainage extracted of the AW3D data had higher correlation with the IBGE reference drainage. Overall, the morphometric parameters calculated for the basin of the Upper Gurguéia (BHAG), from the three selected databases, no show significant differences, indicating the potential of tools and databases for hydrographic analysis of averages and large basins. In any case, it is recommended to inspection and manual correction of the drainage network when applying any automatic extracting method, in order to reduce errors due to limitations of the software. Keywords: Drainage Neytwork. Digital Elevation Model. Geoprocessing.  

scholarly journals Flood vulnerability assessment in the Accra Metropolis, southeastern Ghana

2021 ◽  
Vol 11 (7) ◽  
Author(s):  
Benjamin Wullobayi Dekongmen ◽  
Amos Tiereyangn Kabo-bah ◽  
Martin Kyereh Domfeh ◽  
Emmanuel Daanoba Sunkari ◽  
Yihun Taddele Dile ◽  
...  
Keyword(s):  
Drainage Density ◽  
Geological Structures ◽  
Flood Vulnerability ◽  
Rock Types ◽  
Digital Elevation ◽  
Annual Population ◽  
Density Values ◽  
High Runoff ◽  
Elevation Model ◽  
Very High

AbstractFloods in Ghana have become a perennial challenge in the major cities and communities located in low-lying areas. Therefore, cities and communities located in these areas have been classified as potential or natural flood-prone zones. In this study, the Digital Elevation Model (DEM) of the Accra Metropolis was used to assess the drainage density and elevation patterns of the area. The annual population estimation data and flood damages were assessed to understand the damages and population trend. This research focused primarily on the elevation patterns, slope patterns, and drainage density of the Accra Metropolis. Very high drainage density values, which range between 149 and 1117 m/m2, showed very high runoff converging areas. High drainage density was also found to be in the range of 1117–1702 m/m2, which defined the area as a high runoff converging point. The medium and low converging points of runoff were also found to be ranging between 1702–2563 m/m2 and 2563–4070 m/m2, respectively. About 32% of the study area is covered by natural flood-prone zones, whereas flood-prone zones also covered 33% and frequent flood zones represent 25%. Areas in the Accra Metropolis that fall in the Accraian and Togo series rock types experience high floods. However, the lineament networks (geological structures) that dominate the Dahomeyan series imply that the geological structures in the Dahomeyan series also channel the runoffs into the low-lying areas, thereby contributing to the perennial flooding in the Accra Metropolis.

scholarly journals A new vector-based global river network dataset accounting for variable drainage density

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Peirong Lin ◽  
Ming Pan ◽  
Eric F. Wood ◽  
Dai Yamazaki ◽  
George H. Allen
Keyword(s):  
Spatial Variability ◽  
Flow Direction ◽  
River System ◽  
Drainage Density ◽  
River Network ◽  
River Networks ◽  
Digital Elevation ◽  
Machine Learning Approach ◽  
Elevation Model ◽  
National Hydrography Dataset

AbstractSpatial variability of river network drainage density (Dd) is a key feature of river systems, yet few existing global hydrography datasets have properly accounted for it. Here, we present a new vector-based global hydrography that reasonably estimates the spatial variability of Dd worldwide. It is built by delineating channels from the latest 90-m Multi-Error-Removed Improved Terrain (MERIT) digital elevation model and flow direction/accumulation. A machine learning approach is developed to estimate Dd based on the global watershed-level climatic, topographic, hydrologic, and geologic conditions, where relationships between hydroclimate factors and Dd are trained using the high-quality National Hydrography Dataset Plus (NHDPlusV2) data. By benchmarking our dataset against HydroSHEDS and several regional hydrography datasets, we show the new river flowlines are in much better agreement with Landsat-derived centerlines, and improved Dd patterns of river networks (totaling ~75 million kilometers in length) are obtained. Basins and estimates of intermittent stream fraction are also delineated to support water resources management. This new dataset (MERIT Hydro–Vector) should enable full global modeling of river system processes at fine spatial resolutions.

Prioritization of Sub-Watersheds based on Morphometric parameters in Pare watershed, Arunachal Pradesh, India

2021 ◽  
pp. 53-64
Author(s):  
Waikhom Rahul Singh ◽  
Swapnali Barman ◽  
Nitesh Patidar
Keyword(s):  
Morphometric Parameters ◽  
Development Programs ◽  
Arunachal Pradesh ◽  
Watershed Development ◽  
Prioritization Process ◽  
Morphological Aspects ◽  
Management Measures ◽  
Digital Elevation ◽  
Mountainous Watersheds ◽  
Elevation Model

Mountainous watersheds are constantly under pressure of huge amount of soil loss due to soil erosion. Pare watershed is situated in the eastern Himalayan ranges of Arunachal Pradesh, India, which is subjected to such soil losses and its sub-watersheds are being degraded in many places. Watershed management programs are required in the area in which prioritization of sub-watersheds is one of the first steps. A study has been carried out to address this issue in the area to prioritize 26 sub-watersheds of Pare through morphometric analysis. The study used digital elevation model (DEM) to determine several morphometric parameters of the watershed. The analysis revealed that Pare river is of the 7th order comprising of 6127 stream segments running over the watersheds for about 2448 km. Based on the results obtained, the study area is an elongated well dissected watersheds with high relief and great presence of streams all over the watershed indicating faster runoff peak attainment which is synonymous to rapid transportation of sediment load. The analysis also revealed that SW25 required the top priority in dealing with soil, land and water management measures while least priority could be given to SW7 among all the sub-watersheds in the Pare basin. We suggest various stakeholders who are involved in watershed development programs in the region to take cues from the results obtained in this paper. The results of this study are quite satisfactory in understanding the various morphological aspects of the watershed. Nonetheless, efforts to improve the results can always be made through incorporation of land-use and soil information to enhance the prioritization process so that purpose utilization of the watershed may be reflected in the results.

Lowlands Mapping in Forest Guinea

2013 ◽  
Vol 4 (1) ◽  
pp. 20-34 ◽  
Author(s):  
S. Saïdi ◽  
A. Camara ◽  
L. Gazull ◽  
M. Passouant ◽  
M. Soumaré
Keyword(s):  
Surface Topography ◽  
Digital Elevation Model ◽  
Low Cost ◽  
Mapping Method ◽  
Drainage Network ◽  
Digital Elevation ◽  
Agricultural Potential ◽  
Forested Areas ◽  
Main Index ◽  
Elevation Model

This article presents a lowland mapping method for the Forested Guinea (Guinée Forestière) using a 30 m resolution Digital Elevation Model (DEM) that is currently the best option to analyze large forested areas. This low cost DEM method applies surface topography analysis processes to better discriminate areas with stagnant and/or accumulated water. The main index selected is the immediate proximity of flat areas to drainage network, the former with slope gradients not exceeding 5% (2.86°). The mapped lowlands potential cover a surface of 4516 km2, i.e., 10% of the total area of the region with hydro-agricultural potential.

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