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Falkowski, Tomasz, Piotr Ostrowski, Marek Bogucki, and Dariusz Karczmarz. "The trends in the main thalweg path of selected reaches of the Middle Vistula River, and their relationships to the geological structure of river channel zone." Open Geosciences 10, no. 1 (October 25, 2018): 554–64. http://dx.doi.org/10.1515/geo-2018-0044.
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Abstract Research carried out by the authors’ team in the valleys of many rivers in the Polish Lowlands has shown that the contemporary morphodynamics of channel zones is highly influenced by protrusions of erosion-resistant sub-alluvial bedrock. The article presents the results of analysis of two reaches of the Middle Vistula: near Solec nad Wisłą (km 330-340) and Gołąb (km 382-388), where such protrusions have been found. At each of them, two series of bathymetric measurements were carried out during medium and low water levels in the river channel. The measurements were made using hydrographic sets integrated with a GNSS receiver. The first series of measurements was carried out in July 2004, and the second one in September 2016. In parallel with the bathymetric surveys, low-altitude aerial photographs were taken in 2016 to document the morphology of the channel zone and the condition of the river engineering structures. A comparison of the obtained bathymetric maps shows a high correspondence between the thalweg line from 2004 and that observed twelve years later. This phenomenon proves the significance of the bedrock relief beneath the modern alluvial deposits for the water flow process in the channel. The relief causes the flow to concentrate in specific zones so strongly that it contributes to the damage of river engineering structures that put limits on the channel processes. This trend of concentrating the main thalweg is also accompanied by the diversity of depositional environments of river channel facies, identified along the studied reaches.
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Yepez, Santiago Paul, Alain Laraque, Carlo Gualtieri, Frédéric Christophoul, Claudio Marchan, Bartolo Castellanos, Jose Manuel Azocar, Jose Luis Lopez, and Juan Alfonso. "Morphodynamic change analysis of bedforms in the Lower Orinoco River, Venezuela." Proceedings of the International Association of Hydrological Sciences 377 (April 16, 2018): 41–50. http://dx.doi.org/10.5194/piahs-377-41-2018.
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Abstract. The Orinoco River has the third largest discharge in the world, with an annual mean flow of 37 600 m3 s−1 at its outlet to the Atlantic Ocean. Due to the presence of the Guiana Shield on the right bank, the lower reach of the Orinoco has a plan form characterized by contraction and expansion zones. Typical 1–1.5 km wide narrow reaches are followed by 7–8 km wide reaches. A complex pattern of bed aggradation and degradation processes takes place during the annual hydrological regime. A series of Acoustic Doppler Current Profiler (ADCP) transects were collected on an expansion channel in the Orinoco River, specifically over a fluvial island, representative of the lower Orinoco. In this study, temporal series of bathymetric cartography obtained by ADCP profiles combined with Differential Global Position System (DGPS) measurements (with dual-frequency), were used to recover the local displacement of bed forms in this island. The principal aims of this analysis were: (1) to understand the dynamics and evolution of sand waves and bars at this section and (2) to quantify the volume (erosion vs. accretion) of a mid-channel bar with dunes by applying DEM of Difference (DoD) maps on time series of bathymetric data. This required sampling with ADCP transects during the months of: May 2016; November 2016 and April 2017. Each bathymetric transect was measured twice, 1 day apart and on the same trajectory obtained by a GPS receptor. The spatial analysis of these ADCP transects is presented as a novel tool in the acquisition of time series of bathymetry for a relatively deep section (∼20 m) and under variable flow conditions.
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Arnaud, Fanny, Lalandy Sehen Chanu, Jules Grillot, Jérémie Riquier, Hervé Piégay, Dad Roux-Michollet, Georges Carrel, and Jean-Michel Olivier. "Historical cartographic and topo-bathymetric database on the French Rhône River (17th–20th century)." Earth System Science Data 13, no. 5 (May 10, 2021): 1939–55. http://dx.doi.org/10.5194/essd-13-1939-2021.
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Abstract. Space and time analyses of channel changes, especially within large rivers subject to high levels of human impact, are critical to address multiple questions about rivers in the Anthropocene era. The reconstruction of long-term (> 150 year) evolutionary trajectories permits an understanding of how natural and anthropogenic factors impact hydromorphological and ecological processes in rivers, helps with the design of sustainable management and restoration options, and may also help in the assessment of future changes. However, the reconstruction of channel changes can be challenging: historical data are often scattered across many archives, and the quantity and accuracy of information generally decreases as one goes back in time. This data article provides a historical database of 350 cartographic and topo-bathymetric resources on the French Rhône River (530 km in length) compiled from the 17th to mid-20th century, with a temporal focus prior to extensive river training (1860s). The data were collected in 14 national, regional, and departmental archive services. A table describes the properties of each archived data item and its associated iconographic files. Some of the historical maps are available in a georeferenced format. A GIS layer enables one-click identification of all archive data available for a given reach of the French Rhône River. This database provides substantial new material for deeper analyses of channel changes over a longer time period and at a finer time step compared with previously available data. The database has several potential applications in geomorphology, retrospective hydraulic modelling, historical ecology, and river restoration, as well as permitting comparisons with other multi-impacted rivers worldwide. The dataset is available at https://doi.org/10.1594/PANGAEA.922437 (Arnaud et al., 2020a). Iconographic extracts of the 350 archived items are available at http://photo.driihm.fr/index.php/category/52 (last access: 2 May 2021).
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Atallah, M'hamed, Abdelkrim Hazzab, Abdelali Seddini, Abdellah Ghenaim, and Khaled Korichi. "Inundation maps for extreme flood events: Case study of Sidi Bel Abbes city, Algeria." Journal of Water and Land Development 37, no. 1 (June 1, 2018): 19–27. http://dx.doi.org/10.2478/jwld-2018-0021.
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Abstract Hydrodynamic modelling is used to analyse the inundation behaviour of Sidi Bel Abbes city (North-West of Algeria) during extreme flood events. The study reach, 5.4 km in length, is a section of Wadi Mekerra through Sidi Bel Abbes city. Land and bathymetric surveys were used to create a digital terrain model (DTM) of the river channel and the floodplain. By coupling the geometry with hydrologic data, a two dimensional hydrodynamic model was built. The model is based on integrating Saint-Venant shallow waters (depth averaged) equations through Runge–Kutta discontinuous Galerkin numerical scheme. It was calibrated in terms of roughness coefficients on measured values of water surface elevation and discharge registered in the Sidi Bel Abbes gauging station. The objective is to draw the flood maps under extreme river flood event. The results are helpful for local authorities in order to take the appropriate defence measures in the future.
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Chemagin, Andrey Aleksandrovich. "LOCALITY OF FORMING WINTERING RIVERBED DEPRESSION IN IRTYSH RIVER." Vestnik of Astrakhan State Technical University. Series: Fishing industry 2020, no. 4 (December 30, 2020): 7–21. http://dx.doi.org/10.24143/2073-5529-2020-4-7-21.
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The article describes a new locality of the formed wintering riverbed depression discovered in the erosion zone of the isthmus of conjugate meanders of the Irtysh river for the rational use and effective protection of aquatic biological resources in places of their concentration in the Irtysh river basin (Western Siberia, the Russian Federation. The morphology of the riverbed depression was mapped (relief and bathymetric maps). The maximum depths in the channel depression exceeded 27 m. The channel depression and 4 control river sections were studied. The analysis
of hydroacoustic surveys showed that in the wintering riverbed depression there is, according to the statistical data, higher fish density compared to the control areas: in the water area of the riverbed depression the average fish density made 4 524 species/ha, in the control sections 245-2091 sp./ha. The cluster analysis based on the fish density and the size-taxonomic composition of the ichthyofauna has revealed that the riverbed depression is being separated into a cluster, but at the same time goes to the control section No. 4, which is located downstream, where further erosion of the river channel is registered. In this regard, the minimum protection zone of the wintering channel depression should include the water area of the channel depression and the water area of control section No. 4. In the water areas of the riverbed depression and control sections in the spring period, cyprinids dominate - up to 65% of the total number of fish, percids are represented to a lesser extent - 36.76%, coregonids and pikes - up to 18.18, sturgeons - up to 9.31%. The given locality of the wintering riverbed depression must be included in the list of protected river sections of the Fishing Rules for the West Siberian fishery basin for developing the effective strategy for the protection, restoration and rational use of aquatic biological resources, including rare and endangered fish species of the Irtysh River and the whole Ob-Irtysh basin
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Pacina, Jan, Zuzana Lenďáková, Jiří Štojdl, Tomáš Matys Grygar, and Martin Dolejš. "Dynamics of Sediments in Reservoir Inflows: A Case Study of the Skalka and Nechranice Reservoirs, Czech Republic." ISPRS International Journal of Geo-Information 9, no. 4 (April 18, 2020): 258. http://dx.doi.org/10.3390/ijgi9040258.
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A wide variety of geographic information system tools and methods was used for pre-dam topography reconstruction and reservoir bottom surveying in two dam reservoirs in the Ohře River, Czech Republic. The pre-dam topography was reconstructed based on archival aerial imagery and old maps. The benefits and drawbacks of these methods were tested and explained with emphasis on the fact that not all processed archival data are suitable for pre-dam topography modeling. Bathymetric surveying of a reservoir bottom is presently routine, but in this study, we used a wide combination of bathymetric mapping methods (sonar, ground penetration radar, and sub-bottom profiler) and topographic survey tools (LiDAR and photogrammetry), bringing great benefits for bottom dynamic analysis and data cross-validation. The data that we gathered made it possible to evaluate the formation of the inflow deltas in the reservoirs studied and assess the sediment reworking during recent seasonal drawdowns. A typical inflow delta was formed in the deeper of the two studied reservoirs, while the summer 2019 drawdown caused the formation and incision of a temporary drawdown channel and erosive downstream transport of approximately 1/10 of the delta body thickness in approximately 1/10 of the delta transverse size. No inflow delta was formed in the shallower of the studied reservoirs, but unexpectedly extensive sediment reworking was observed in the inflow part of the reservoir. Both the studied reservoirs and the pre-dam river floodplain have accumulated historical contamination by risk elements such as As, Hg, Pb; thus, the enhanced erosion of existing sediment bodies expected in the future, owing to more frequent droughts and global climate change, will endanger the ecological quality of the water and solids outflowing from the reservoirs.
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Stateczny, Andrzej, Wioleta Błaszczak-Bąk, Anna Sobieraj-Żłobińska, Weronika Motyl, and Marta Wisniewska. "Methodology for Processing of 3D Multibeam Sonar Big Data for Comparative Navigation." Remote Sensing 11, no. 19 (September 26, 2019): 2245. http://dx.doi.org/10.3390/rs11192245.
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Autonomous navigation is an important task for unmanned vehicles operating both on the surface and underwater. A sophisticated solution for autonomous non-global navigational satellite system navigation is comparative (terrain reference) navigation. We present a method for fast processing of 3D multibeam sonar data to make depth area comparable with depth areas from bathymetric electronic navigational charts as source maps during comparative navigation. Recording the bottom of a channel, river, or lake with a 3D multibeam sonar data produces a large number of measuring points. A big dataset from 3D multibeam sonar is reduced in steps in almost real time. Usually, the whole data set from the results of a multibeam echo sounder results are processed. In this work, new methodology for processing of 3D multibeam sonar big data is proposed. This new method is based on the stepwise processing of the dataset with 3D models and isoline maps generation. For faster products generation we used the optimum dataset method which has been modified for the purposes of bathymetric data processing. The approach enables detailed examination of the bottom of bodies of water and makes it possible to capture major changes. In addition, the method can detect objects on the bottom, which should be eliminated during the construction of the 3D model. We create and combine partial 3D models based on reduced sets to inspect the bottom of water reservoirs in detail. Analyses were conducted for original and reduced datasets. For both cases, 3D models were generated in variants with and without overlays between them. Tests show, that models generated from reduced dataset are more useful, due to the fact, that there are significant elements of the measured area that become much more visible, and they can be used in comparative navigation. In fragmentary processing of the data, the aspect of present or lack of the overlay between generated models did not relevantly influence the accuracy of its height, however, the time of models generation was shorter for variants without overlay.
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Legleiter, Carl, and Brandon Overstreet. "Measuring the Morphology and Dynamics of the Snake River by Remote Sensing." UW National Parks Service Research Station Annual Reports 34 (January 1, 2011): 53–67. http://dx.doi.org/10.13001/uwnpsrc.2011.3859.
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The Snake River is a central component of Grand Teton National Park, and this dynamic fluvial system plays a key role in shaping the landscape and maintaining a diversity of habitat conditions. The riverâs inherent variability and propensity for change complicate effective characterization of this important resource, however; conventional, ground-based methods are not adequate for this purpose. Remote sensing provides an appealing alternative that could facilitate resource management while providing novel insight on factors influencing channel form and behavior. This study evaluates the potential for using optical data to measure the morphology and dynamics of a large, complex river such as the Snake. More specifically, we assessed the feasibility of estimating flow depth from multispectral satellite images acquired in September 2011. Our initial results indicate that reliable maps of river bathymetry can be produced from such data. We are also examining channel changes associated with a prolonged period of high flow during the 2011 snowmelt runoff season by comparing these satellite images with digital aerial photography from August 2010. An extensive field data set on flow velocities provides some hydraulic context for the observed morphodynamics. More sophisticated hyperspectral and LiDAR data sets are scheduled for collection in 2012, along with additional field measurements.
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Karczmarz, Dariusz, Przemysław Mądrzycki, Henryk Szkudlarz, Wojciech Puchalski, Joanna Gorczyca, Marcin Ciepliński, Tomasz Falkowski, and Piotr Ostrowski. "Evaluation of the possibilities to use imagery reconnaissance sensors to identify the geological-engineering conditions in lowland river channels." Journal of KONBiN 48, no. 1 (December 1, 2018): 169–89. http://dx.doi.org/10.2478/jok-2018-0052.
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Abstract The article concerns the issue of using imagery reconnaissance sensors for the identification of geological-engineering conditions in river channels, in the aspect of evaluating the forcing of a water obstacle. It discusses the issues associated with using air platforms (manned and unmanned) in remote sensing surveying of selected fragments of the Vistula and Bug river channels and the correct interpretation of the obtained results, through their verification using bathymetric tests conducted directly in the river channels.
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Dos Santos, Vanessa Cristina, and José Cândido Stevaux. "GÊNESE DE BARRAS DE SOLDAMENTO E SUAS CARACTERÍSTICAS MORFOLÓGICAS: ALTO RIO PARANÁ, BRASIL / Attachment Bars Genesis and Morphological Features: Upper Paraná River, Brazil." Geographia Meridionalis 2, no. 1 (June 29, 2016): 127. http://dx.doi.org/10.15210/gm.v2i1.8102.
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O rio Paraná, em seu trecho natural, é caracterizado por canais secundários de diferentes ordens de tamanho, separando diversas ilhas e barras fluviais. As barras fluviais apresentam grande porte e suas formas mudam constantemente conforme a magnitude do fluxo. Este estudo apresenta a caracterização morfológica de uma barra de soldamento e suas adjacências, situadas junto à ilha Santa Rosa, no alto rio Paraná. Para tanto, a morfologia da barra foi comparada em dois momentos hidrológicos distintos através de levantamentos com aparelho de batimetria. Os resultados evidenciam que a morfologia da barra estudada está diretamente influenciada pelas oscilações da vazão do rio Paraná. No período de águas altas há maior retrabalhamento da forma, e preservação parcial em período de águas médias. A análise da distribuição das formas adjacentes à barra de soldamento permitiu constatar que o canal principal possui mais energia, já que apresenta formas íngremes e profundas, e o canal secundário indica menor energia de fluxo por apresentar formas mais suaves.AbstractThe Paraná River, in its natural reach is characterized by secondary channels of different size orders, which separates several islands and bars. Fluvial bars are large and their forms change constantly due to the flow. This study presents the morphological characterization of an attachment bar and its adjacencies, located nearby the island Santa Rosa, in the upper Paraná River. Therefore, the morphology of the bar was compared in two distinct hydrological moments through surveys with bathymetry equipment. The results indication that the morphology of the studied bar is directly influenced by fluctuations in the flow of the Paraná River. In the period of high water level there is more reworking of the forms and partial preservation in average water level. The analysis of the distribution of forms adjacent to the attachment bar allowed establishing that the main channel is more energetic, as it presents abrupt and deep forms and the secondary channel indicates lower energy flow by presenting smoother forms.Keywords:Paraná River, Fluvial Geomorphology, Morphology, Attachment Bar
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Benassai, Guido, Pietro Aucelli, Giorgio Budillon, Massimo De Stefano, Diana Di Luccio, Gianluigi Di Paola, Raffaele Montella, Luigi Mucerino, Mario Sica, and Micla Pennetta. "Rip current evidence by hydrodynamic simulations, bathymetric surveys and UAV observation." Natural Hazards and Earth System Sciences 17, no. 9 (September 12, 2017): 1493–503. http://dx.doi.org/10.5194/nhess-17-1493-2017.
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Abstract. The prediction of the formation, spacing and location of rip currents is a scientific challenge that can be achieved by means of different complementary methods. In this paper the analysis of numerical and experimental data, including RPAS (remotely piloted aircraft systems) observations, allowed us to detect the presence of rip currents and rip channels at the mouth of Sele River, in the Gulf of Salerno, southern Italy. The dataset used to analyze these phenomena consisted of two different bathymetric surveys, a detailed sediment analysis and a set of high-resolution wave numerical simulations, completed with Google EarthTM images and RPAS observations. The grain size trend analysis and the numerical simulations allowed us to identify the rip current occurrence, forced by topographically constrained channels incised on the seabed, which were compared with observations.
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Akyurek, Z., B. Bozoğlu, S. Sürer, and H. Mumcu. "Upstream structural management measures for an urban area flooding in Turkey." Proceedings of the International Association of Hydrological Sciences 370 (June 11, 2015): 45–50. http://dx.doi.org/10.5194/piahs-370-45-2015.
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Abstract. In recent years, flooding has become an increasing concern across many parts of the world of both the general public and their governments. The climate change inducing more intense rainfall events occurring in short period of time lead flooding in rural and urban areas. In this study the flood modelling in an urbanized area, namely Samsun-Terme in Blacksea region of Turkey is performed. MIKE21 with flexible grid is used in 2-dimensional shallow water flow modelling. 1 × 1000−1 scaled maps with the buildings for the urbanized area and 1 × 5000−1 scaled maps for the rural parts are used to obtain DTM needed in the flood modelling. The bathymetry of the river is obtained from additional surveys. The main river passing through the urbanized area has a capacity of 500 m3 s−1 according to the design discharge obtained by simple ungauged discharge estimation depending on catchment area only. The upstream structural base precautions against flooding are modelled. The effect of four main upstream catchments on the flooding in the downstream urban area are modelled as different scenarios. It is observed that if the flow from the upstream catchments can be retarded through a detention pond constructed in one of the upstream catchments, estimated Q100 flood can be conveyed by the river without overtopping from the river channel. The operation of the upstream detention ponds and the scenarios to convey Q500 without causing flooding are also presented. Structural management measures to address changes in flood characteristics in water management planning are discussed.
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Scottá, Fernando Comerlato, Mauro Michelena Andrade, Vicente Oliveira Silva Junior, Natacha Oliveira, Jair Weschenfelder, Eduardo Calixto Bortolin, and José Carlos Nunes. "GEOACOUSTIC PATTERNS OF THE GUAÍBA RIVER BOTTOM AND SUBBOTTOM AND THEIR RELATIONSHIP WITH SEDIMENTARY AND HYDRODYNAMIC PROCESSES." Brazilian Journal of Geophysics 37, no. 1 (March 27, 2019): 105. http://dx.doi.org/10.22564/rbgf.v37i1.1991.
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ABSTRACT. This work aimed at studying the bottom and sub-bottom geoacoustics of the Guaíba River, whose echo patterns are related to hydrodynamic patterns and sedimentary processes. A total of 324 km of seismic transects were surveyed using the Stratabox high-frequency (10 kHz) profiler with concomitant imaging using a side-scan sonar in the northern and central areas of the Guaíba system. The records were interpreted with the aid of complementary data (bathymetry and bottom samples), and maps containing the spatial arrangement of echo-characters were developed. The echo-characters were classified into seven different types according to the presence of sediments controlled by the hydrodynamics of the system or modified by human action. In general, the echoes related to the deposition of fine sediments occurred in deeper areas, the navigation channel or surrounding areas. The echoes in the shallower areas presented strong acoustic reflectivity at sites with lower deposition of fine sediments and predominance of sandy sediments. The occurrence and morphology of asymmetric subaqueous dunes indicated a predominant north-to-south flow and a river behavior.Keywords: shallow geophysics, sedimentology, hydrodynamics, geoprocessing.RESUMO. Este trabalho tem por objetivo o estudo geoacústico de fundo e subfundo do rio Guaíba, cujos padrões de ecos são relacionados aos padrões hidrodinâmicos e aos processos sedimentares atuantes. Foram levantados 324 km de perfis sísmicos em extensão, com o perfilador de alta frequência (10 kHz) Stratabox e concomitante imageamento com Sonar de Varredura Lateral nas áreas Norte e Central do Guaíba. Os registros foram interpretados com o auxílio de dados complementares (batimetria e amostras de fundo) e foram confeccionados mapas com a disposição espacial dos eco-caráteres. Os eco-caráteres foram classificados em sete diferentes tipos, de acordo com a presença de sedimentos controlados pela hidrodinâmica do sistema ou modificados pela ação humana. De uma forma geral, os ecos relacionados à deposição de sedimentos finos ocorrem nas áreas mais profundas, no canal de navegação ou adjacências. Os ecos nas áreas mais rasas apresentam forte refletividade acústica, em locais com menor deposição de sedimentos finos e predomínio de sedimentos arenosos. A ocorrência e morfologia de dunas subaquosas assimétricas indicam um fluxo preponderante no sentido Norte – Sul e um comportamento fluvial do sistema aquático.Palavras-chave: geofísica rasa, sedimentologia, hidrodinâmica, geoprocessamento.
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Huyghe, Pascale, Michel Foata, Eric Deville, Georges Mascle, and Caramba Working Group. "Channel profiles through the active thrust front of the southern Barbados prism." Geology 32, no. 5 (May 1, 2004): 429–32. http://dx.doi.org/10.1130/g20000.1.
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Abstract Submarine channels of the Orinoco River were analyzed using high-quality, dense- coverage bathymetric and seismic data provided by a recent marine survey on the southern Barbados prism. Analysis of the syntectonic sediments on seismic profiles shows that the four to five frontmost structures show evidence of recent tectonic movement. Slope analysis of the major channels was performed. From their headwaters to domains of little or no active tectonics, the channels display <0.2% slope and form levees. Slope and incision increase gradually in domains of moderate tectonics, but deep canyons with ∼2% mean slope form where the channels cross the active frontal folds of the prism. Detailed correlation between the active structures, their geometry, and canyon slope suggest that systematic variations in channel gradient highlight variations in substrate uplift rate. Steep slopes induced by uplift accelerate sediment flow and enhance incision. Nonetheless, such slope analysis is subject to complications introduced by variations in sediment flux and transient erosional conditions.
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Lemenkova, Polina. "Sediment thickness in the Bay of Bengal and Andaman Sea compared with topography and geophysical settings by GMT." Ovidius University Annals of Constanta - Series Civil Engineering 22, no. 1 (December 1, 2020): 13–21. http://dx.doi.org/10.2478/ouacsce-2020-0002.
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Abstract The study presents an analysis of the sediment thickness compared with bathymetric and geophysical settings in the Bay of Bengal and Andaman Sea, Indian Ocean. It uses a combination of the high-resolution data: topographic GEBCO, satellite and marine gravity anomalies, EGM2008 geoid and GlobSed to visualize the correlation between relief, gravity and trends in continent-ocean sediment transport. The results include thematic maps and 3D model showing increased sediment thickness in the Bengal Fan (8,0 to 8,2 km) in NE direction with maximum in Ganges Fan (16,2 km), and southward decrease in the Andaman Sea from Irrawaddy river mouth (6-7 km) to the Strait of Malacca (1-2 km). All maps and 3D model have been plotted by Generic Mapping Tools (GMT) cartographic scripting toolset version 6.0.0.
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Arseni, Maxim, Adrian Rosu, Madalina Calmuc, Valentina Andreea Calmuc, Catalina Iticescu, and Lucian Puiu Georgescu. "Development of Flood Risk and Hazard Maps for the Lower Course of the Siret River, Romania." Sustainability 12, no. 16 (August 14, 2020): 6588. http://dx.doi.org/10.3390/su12166588.
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The Siret River is one of the most important tributaries of the Danube River in the Romanian territory. With a total length of 596 km in this territory, the confluence section of the Siret River with the Danube represents an area where major floods have occurred over time. In the last 50 years, over 20 floods have been recorded in the lower area of the Siret River; and the most recent important flood, which happened in 2010, had a negative impact on the local population, the environment, and the economy. Although it is a buffer zone, the Danube River has a significant impact on the discharge rate of the Siret River. Since few studies have been conducted on the prediction of flooding in the lower area of the Siret River, the present study aims at presenting the most important steps to be taken for designing risk and hazard maps for floods, which could be further applied to other rivers. The confluence of the Siret River with the Danube, a distance of 35 km upstream, was chosen as a study area. Techniques of topographic and bathymetric measurements were combined in order to design the risk and hazard maps for floods in this area and to improve the digital terrain model of the minor riverbed for the studied river area. The 1D hydrodynamic model of the HEC-RAS software was used in this research for developing the flood risk and flood hazard maps. The hazard and risk maps were generated based on 10%, 5%, and 1% flood scenarios, which are in accordance with Floods Directive 2007/60/EC; no historical data were available for the 0.1% scenarios. Thus, in a flood scenario that can occur every 100 years, about 9500 inhabitants are vulnerable at a medium flood risk. In this scenario, over 19.5 km of road infrastructure, about 16.5 km of railways, eight cultural heritage indicators, and three environmental indicators may be affected.
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Molen, Wim van der, Holly Watson, and David Taylor. "ALLOWANCE FOR FORMATION OF MEGA SAND WAVES ON THE SEABED IN THE DESIGN OF FAIRWAYS IN ESTUARIES WITH STRONG CURRENTS." Coastal Engineering Proceedings, no. 36v (December 28, 2020): 35. http://dx.doi.org/10.9753/icce.v36v.sediment.35.
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The declared depth in port access channels is often maintained by dredging and monitored by regular bathymetric surveys. However, at remote sites these activities are not cost-effective and the channel depth would need to be defined based on the surveyed depth plus an allowance for sedimentation and variability in bed levels. This allowance can especially be significant in estuaries with strong tidal currents, where mega bedforms, including sand waves, develop on the seabed due to the prevailing strong current flows. The mega sand waves are highly mobile and fluctuate in height as they migrate over the seabed. Mega sand waves and mega ripples with a height up to approx. 3.2 m were observed in multi-beam bathymetric survey undertaken in the offshore entrance to the Geba River estuary in Guinea Bissau. Supramax bulk carriers with a draft of 11-12 m are planned to transit this area on departure from a proposed phosphate export terminal located further upstream in the estuary.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/5Gmy9yQkfno
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Fassnacht, Steven R., and F. Malcolm Conly. "Persistence of a scour hole on the East Channel of the Mackenzie Delta, N.W.T." Canadian Journal of Civil Engineering 27, no. 4 (August 1, 2000): 798–804. http://dx.doi.org/10.1139/l00-022.
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Anomalies in the bathymetry of river channels are of great practical concern for designing sub-bed pipeline crossings. Of particular interest is the long-term stability of deep holes. Bathymetric evidence indicates that one unusually deep hole in the East Channel of the Mackenzie River, referred to as a scour hole, has existed as early as 1956. Detailed hydraulic and morphologic data were first collected in 1985, and again in 1992 to assess the spatial and temporal stability of the feature. Even with a record flood on the Mackenzie River in 1988, the hole, with a maximum depth approaching 30 m, was vertically stable over the 7-year period. However, lateral erosion and sedimentation have resulted in a shift in the horizontal position of the scour hole, with a maximum horizontal erosion of approximately 2 m/a. The average rate of lateral outward movement was observed to be 0.8 m/a.Key words: Mackenzie Delta, rivers, fluvial sediment, channel stability, scour, scour hole.
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Cassol, Willian Ney, Sylvie Daniel, and Éric Guilbert. "A Segmentation Approach to Identify Underwater Dunes from Digital Bathymetric Models." Geosciences 11, no. 9 (August 25, 2021): 361. http://dx.doi.org/10.3390/geosciences11090361.
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The recognition of underwater dunes has a central role to ensure safe navigation. Indeed, the presence of these dynamic landforms on the seafloor represents a hazard for navigation, especially in navigation channels, and should be at least highlighted to avoid collision with vessels. This paper proposes a novel method dedicated to the segmentation of these landforms in the fluvio-marine context. Its originality relies on the use of a conceptual model in which dunes are characterized by three salient features, namely the crest line, the stoss trough, and the lee trough. The proposed segmentation implements the conceptual model by considering the DBM (digital bathymetric model) as the seafloor surface from which the dunes shall be segmented. A geomorphometric analysis of the seabed is conducted to identify the salient features of the dunes. It is followed by an OBIA (object-based image analysis) approach aiming to eliminate the pixel-based analysis of the seabed surface, forming objects to better describe the dunes present in the seafloor. To validate the segmentation method, more than 850 dunes were segmented in the fluvio-marine context of the Northern Traverse of the Saint-Lawrence river. A performance rate of nearly 92% of well segmented dunes (i.e., true positive) was achieved.
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Fajer, Maria. "Changes in river channel pattern as a result of the construction, operation and decommissioning of watermills – the case of the middle reach of the River Liswarta near Krzepice, Poland." Environmental & Socio-economic Studies 6, no. 1 (March 1, 2018): 25–37. http://dx.doi.org/10.2478/environ-2018-0004.
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AbstractChanges in river channel pattern in the middle reach of the River Liswarta and in the lower reaches of its tributaries near Krzepice were analysed, and were related to the construction, operation and decommissioning of watermills. For this purpose, old maps which covered the period from the beginning of the 18th century until the 20th century were used alongside written historical sources. Maps from the first half of the 19th century provided valuable source material. Traces of old mill water systems in the valley floor were analysed on the basis of a numerical terrain model and aerial photographs as well as on the basis of detailed geomorphological mapping. The research made it possible to determine the locations of former mills mentioned in written historical sources and also changes in the course of river channels related to mill construction. It was found that some reaches of the River Liswarta channel and the estuary reach of its tributary River Bieszcza were in fact old mill races. These mill races account for around 31% of the length of the river channel reaches analysed. Analysis of old maps indicated that in the 19th century, the River Liswarta near Krzepice had multiple channels. This development of the River Liswarta channel was not only the result of natural geological, geomorphological and climate conditions, but also the product of watermill construction, since some channels within this network were artificial canals, including mill races. As a result of the construction of mill races, river channel reaches ranging from 1 to 2.5 km in length were shifted. Of the mills studied, as many as 80% ceased to exist in different parts of the period covered by the research. Traces of some of them can still be found in the form of ruins of foundations or of a water system with the remains of hydraulic structures, while some have only left their mark on the river channel pattern.
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Gudmundsson, Snaevarr, and Helgi Björnsson. "Channels of the glacial river Jökulsá á Breiðamerkursandi." JOKULL 70 (April 15, 2021): 119–28. http://dx.doi.org/10.33799/jokull2020.70.119.
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The glacial river Jökulsá á Breiðamerkursandi drains the Jökulsárlón tidal lagoon (27 km2), in Southeast Iceland. Despite being the shortest glacial outlet (0.6 km), it is among the most voluminous rivers in Iceland, with an estimated average drainage of 250–300 m3/s and has doubled its volume at peak runoff. Until a bridge was established, this was one of Iceland’s most infamous river and for travellers, cruising on horseback, the greatest obstacle to cross on the main road. The river began shaping its present channel in the late 19th century but was not permanently settled until the mid-20th century. Before that it used to wander around the fan, occasionally in several branches, or as a single heavy moving water. In this paper we present a map of its known runoffs and channels that were formed in the 19th and 20th centuries. Few channels were digitized from old maps, but several of those were identified and recorded by the late Flosi Björnsson (1906–1993), a farmer from the Kvísker, who guided travellers across the river before the bridge was built. The Breiðamerkurjökull outlet glacier of Vatnajökull, Southeast Iceland, advanced 10–15 km during the Little Ice Age. During the LIA advance the wide fan shaped shore in front of Breiðamerkurjökull gradually extended outward by >1 km, mainly due to sediment deposition by the Jökulsá river and few other temporal glacial river branches. At the turn of the 20th century the outlet glacier started to retreat slowly and in the 1930s terminal lakes were formed. With the formation of the Jökulsárlón tidal lagoon river dumping at the shore terminated and was replaced by a progressive coastal erosion. Currently ca. 0.9 km has eroded off the coast since the 1930s. A 0.65 km wide strip now remains between the coast and Jökulsárlón tidal lagoon, where the Jökulsá river and the remains of its former runway channels are located.
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Bolaños, Rodolfo, Jennifer M. Brown, Laurent O. Amoudry, and Alejandro J. Souza. "Tidal, Riverine, and Wind Influences on the Circulation of a Macrotidal Estuary." Journal of Physical Oceanography 43, no. 1 (January 1, 2013): 29–50. http://dx.doi.org/10.1175/jpo-d-11-0156.1.
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Abstract The effect of tides, river, wind and Earth’s rotation on the three-dimensional circulation in the Dee, a macrotidal estuary, are investigated using a fine-resolution model. The interactions of the large tidal amplitude, currents, river, and wind-generated circulation require baroclinic and unsteady studies to properly understand the estuarine dynamics. Assessment of the model skill has been carried out by model–observation comparisons for salinity, which is the main control for density, surface elevation, current, and turbulence. Stationary nondimensional numbers were only partially able to characterize the dynamics in this (real) complex macrotidal estuary. At low water, tidal straining and constrained river flow cause stratification. Large spatial variability occurs in the current and residual patterns, with flood-dominated maximum values occurring within the tidal channels. The tides control residual circulation by modulating stratification through tidal straining and bathymetric constraint on river flow. Tide–stratification–river interaction causes an unsteady pattern of residual circulation and tidal pulses. River-induced pulses are enhanced near low tide–inducing density-driven circulation. Wind effects are concentrated near the surface, mainly occurring at high tide because of increased fetch. Even though Coriolis has, overall, a small contribution it produces tidal pulses modifying the current and salinity distribution.
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Ji, Xiaomin, Youpeng Xu, Longfei Han, and Liu Yang. "Impacts of urbanization on river system structure: a case study on Qinhuai River Basin, Yangtze River Delta." Water Science and Technology 70, no. 4 (June 18, 2014): 671–77. http://dx.doi.org/10.2166/wst.2014.278.
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Stream structure is usually dominated by various human activities over a short term. An analysis of variation in stream structure from 1979 to 2009 in the Qinhuai River Basin, China, was performed based on remote sensing images and topographic maps by using ArcGIS. A series of river parameters derived from river geomorphology are listed to describe the status of river structure in the past and present. Results showed that urbanization caused a huge increase in the impervious area. The number of rivers in the study area has decreased and length of rivers has shortened. Over the 30 years, there was a 41.03% decrease in river length. Complexity and stability of streams have also changed and consequently the storage capacities of river channels in intensively urbanized areas are much lower than in moderately urbanized areas, indicating a greater risk of floods. Therefore, more attention should be paid to the urban disturbance to rivers.
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Schenker, André, and Markus Zumsteg. "Flusskorridore und Auenstrukturen im schweizerischen Mittelland (nördliches Alpenvorland) | River corridors and alluvial structures in Central Switzerland (northern sub-alpine area)." Schweizerische Zeitschrift fur Forstwesen 152, no. 9 (September 1, 2001): 394–99. http://dx.doi.org/10.3188/szf.2001.0394.
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Long-term spatial variation of river channel distribution in this alluvial valley zone is described for two examples by analysing historical maps covering a period of over 300 years. Such a time series enables the identification of the occupied river corridor or«Pendelband». Two river sections in northern Switzerland were chosen, one of the Aare river and one of the Reuss river to analyse the spatial evolution of the river channels over time, as well as alluvial structures. Knowledge of the river corridor as an historical reference give us an important guideline when developing appropriate regional measures for river restoration projects.
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Kargapolova, I. "River channel response to runoff variability." Advances in Geosciences 14 (May 6, 2008): 309–16. http://dx.doi.org/10.5194/adgeo-14-309-2008.
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Abstract. The focus of this study was to determine river runoff impacts on channel evolution during the last centuries. Comparing a number of maps from the 18th–21th centuries and space images in concert with hydrological data we estimated natural trends, cycles and the intensity of channel formation for periods of high and low runoff. Our analysis for a long period of time enable us assessing mean and maximum rates of erosion and accumulation of river channels and bank dynamics under different conditions. Using links between runoff values and meander size we predict and reconstruct these for several Russian rivers. For forecast validation we use cases of high scale runoff change – water transfer from one basin to another.
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Hu, Kelin, Ehab Meselhe, and J. Andrew Nyman. "The Effect of Phragmites australis Dieback on Channel Sedimentation in the Mississippi River Delta: A Conceptual Modeling Study." Water 13, no. 10 (May 18, 2021): 1407. http://dx.doi.org/10.3390/w13101407.
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Phragmites australis is a globally distributed wetland plant. At the mouth of the Mississippi River, P. australis on natural levees of the network of distributary channels appears to increase the flow in the deep draft navigation channel, which, in turn, may reduce the sedimentation and benefit the navigation dredging. For several years, P. australis has been dying in the Mississippi River’s Bird’s Foot Delta, which appears to be shortening the distributary channels and increasing the lateral flow from the remaining portions. A conceptual model based on D-FLOW FM was applied to calculate channel sedimentation in a series of idealized deltaic systems to predict the consequences of P. australis dieback and other factors that diminish the delta complexity, such as sea-level rise and subsidence, on sedimentation in the distributary channels. Channel complexity in each system, which was quantified with an index ranging from 0 to 10 that we developed. Model results indicate that sedimentation was insensitive to the channel complexity in simple deltas but was sensitive to the channel complexity in complex deltas, such as the current Mississippi River Delta with extensive P. australis. Channel sedimentation remains stable from 0 until the channel complexity index reaches 6. In more complex deltas, the sedimentation decreases rapidly as the channel complexity increases. The sedimentation is also affected by waves, river discharge, sediment concentration, grain sizes, and bed level. River managers in Louisiana may benefit from new models based on bathymetric data throughout the Bird’s Foot Delta; data on the effects of the P. australis belowground biomass on bank erodibility across a range of current velocities; and data on the effects of P. australis stem density, diameter, and height on the lateral flow across a range of river stages and tidal stages to help them decide how much to respond to Phragmites dieback. Options include increased navigation dredging, increased restoration of the channel complexity via a thin layer of sediment deposition on natural levees and the planting of more salt-tolerant vegetation on natural levees.
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Mahdade, Mounir, Nicolas Le Moine, Roger Moussa, Oldrich Navratil, and Pierre Ribstein. "Automatic identification of alternating morphological units in river channels using wavelet analysis and ridge extraction." Hydrology and Earth System Sciences 24, no. 7 (July 14, 2020): 3513–37. http://dx.doi.org/10.5194/hess-24-3513-2020.
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Abstract. The accuracy of hydraulic models depends on the quality of the bathymetric data they are based on, whatever the scale at which they are applied. The along-stream (longitudinal) and cross-sectional geometry of natural rivers is known to vary at the scale of the hydrographic network (e.g., generally decreasing slope, increasing width in the downstream direction), allowing parameterizations of main cross-sectional parameters with large-scale proxies such as drainage area or bankfull discharge (an approach coined downstream hydraulic geometry, DHG). However, higher-frequency morphological variability (i.e., at river reach scale) is known to occur for many stream types, associated with varying flow conditions along a given reach, such as the alternate bars or the pool–riffle sequences and meanders. To consider this high-frequency variability of the geometry in the hydraulic models, a first step is to design robust methods to characterize the scales at which it occurs. In this paper, we introduce new wavelet analysis tools in the field of geomorphic analysis (namely, wavelet ridge extraction) to identify the pseudo-periodicity of alternating morphological units from a general point of view (focusing on pool–riffle sequences) for six small French rivers. This analysis can be performed on a single variable (univariate case) but also on multiple variables (multivariate case). In this study, we choose a set of four variables describing the flow degrees of freedom: velocity, hydraulic radius, bed shear stress, and a planform descriptor that quantifies the local deviation of the channel from its mean direction. Finally, this method is compared with the bedform differencing technique (BDT), by computing the mean, median, and standard deviation of their longitudinal spacings. The two methods show agreement in the estimation of the wavelength in all reaches except one. The method aims to extract a pseudo-periodicity of the alternating bedforms that allow objective identification of morphological units in a continuous approach with the maintenance of correlations between variables (i.e., at many station hydraulic geometry, AMHG) without the need to define a prior threshold for each variable to characterize the transition from one unit to another.
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Wierzbicki, Grzegorz, Piotr Ostrowski, and Tomasz Falkowski. "Applying floodplain geomorphology to flood management (The Lower Vistula River upstream from Plock, Poland)." Open Geosciences 12, no. 1 (October 14, 2020): 1003–16. http://dx.doi.org/10.1515/geo-2020-0102.
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AbstractUsing remote sensing extended on geological and topographical maps and verified by the field work, we present the flood management and study the geomorphic features of the floodplain of a large, sand bed, untrained but embanked river in order to determine the flood hazard and to predict future flood scenarios. In geomorphological mapping, we focus on the landforms: crevasse channels and splays, flood basin, chute channels, side arms, floodplain channels, dunes and fields of aeolian sand. We base the flood risk assessment on consultations with environmental engineers who design new technical structures that control inundation (cut-off walls and lattice levees). We describe a levee breach as a result of piping (inner erosion) in a high hydraulic gradient condition and its effect (scour hole) as an erosional landform consistent with the repetitive pattern of erosion and deposition formed by an overbank flow on a floodplain. We reveal an existence of homogenous morphodynamic reaches in the river valley.
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Malik, Ireneusz, Małgorzata Wistuba, Agnieszka Czajka, Katarzyna Łuszczyńska, and Stanisław Czaja. "The destruction of natural river reaches due to improper land development - an example of the valleys of Czadeczka and Krężelka rivers (Beskid Śląski Mts) / Niszczenie naturalnych odcinków koryt rzecznych na skutek niewłaściwej zabudowy – przykład dolin Czadeczki i Krężelki (Beskid Śląski)." Ochrona Srodowiska i Zasobów Naturalnych 26, no. 3 (September 1, 2015): 36–41. http://dx.doi.org/10.1515/oszn-2015-0010.
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Abstract Channels of Czadeczka and Krężelka rivers (Beskidzie Śląski Mts) are at present subjected to regulation because of which these rivers have lost their natural character, partially still preserved. The reasons for the river regulation have been analysed. Using archival maps, the buildings erection time has been analysed on valley floors, in the immediate vicinity of river channels for the period 1790-2012. Next, the distribution of existing buildings has been compared with hydraulic structures in the channels developed in order to regulate the Czadeczka and the Krężelka reaches, such as: concrete and stone embankments reinforcing the channel banks, check dams on channel bottoms. Results indicate a strong correlation between the number of buildings on valley floors in the 20th century and channel regulation. The mechanism of destroying rare, preserved natural river reaches is based on irrational permission allowing construction of buildings in areas threatened by floods and lateral erosion of rivers. Consequently, the inhabitants, in fear of floods and erosion of land or house foundations, seek river regulation that gives them a false sense of security. Natural river reaches are destroyed though efficient protection against floods and lateral erosion is still not provided and the range of possible losses increases even more due to continued building erection.
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Ivanov, Eugen. "THE PRECONDITIONS OF MODERN LANDSCAPES FORMING BETWEEN WESTERN BUG, RATA AND SOLOKIA RIVERS (Part 2)." PROBLEMS OF GEOMORPHOLOGY AND PALEOGEOGRAPHY OF THE UKRANIAN CARPATHIANS AND ADJACENT AREAS, no. 09 (01) (September 25, 2019): 49–61. http://dx.doi.org/10.30970/gpc.2019.1.2801.
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Actual problems of origin, formation, anthropogenic transformation and disappearance modern geosystems between Western Bug, Rata and Solokiya rivers are considered. Special attention devoted to formation conditions research of Yastrubetska Delta as uncharacteristic for region of the Western Bug river valley. Based on retrospective-geographic analysis of literature and cartographic sources of the XVIII–XX centuries are traced stages of the Yastrubetska delta geosystems development and surrounding landscapes of between-river basin. In the second part of article analyzes the large-scale (1 : 25,000) cartographic works, in particular, the Austrian maps of the Third Topographic Survey (1869–1887), the Polish maps of the Military Geographical Institute (1929–1939) and the USSR Soviet General Staff maps (1968–1989). An overview of last three of five historical and geographical stages topographic maps made it possible to investigate and interpret conditions of Small-Polissya landscapes functioning and development in second half of XIX-th – second half of XX-th centuries. Maps of scale 1 : 50,000 – 1 : 300,000 used for clarifying geographical and landscape-ecological situation. The main tendencies of Western Bug, Rata and Solokiya rivers interfluve landscapes transformation for the last 240 years was analyzed. The best indicator for natural conditions transformation are changes in river network, forestation and territory bogging. The analysis of cartographic materials shows that the majority of channels and distributaries of Western Bug and its tributaries, especially within limits of Yastrubetska Delta and a significant reduction of forested areas and wetlands. Key words: landscape; geosystem; river valley; channel; delta; rivers interfluve.
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Gilbert, Robert, and John Shaw. "Glacial and early postglacial lacustrine environment of a portion of northeastern Lake Ontario." Canadian Journal of Earth Sciences 29, no. 1 (January 1, 1992): 63–75. http://dx.doi.org/10.1139/e92-008.
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A deep channel in bedrock extending to more than 25 m below sea level occurs along the north shore of the otherwise uniformly shallow Kingston basin of Lake Ontario. Bathymetric and subbottom acoustic data are used to map the topography of the channel and to reconstruct its late glacial and postglacial sedimentary history. The results are interpreted as showing that the large channel and smaller channels nearby were created by high-velocity subglacial meltwater flow. Acoustic facies assemblages of sediments deposited in the channels record patchy deposition, or deposition followed by partial erosion, of glacial sediments on the bedrock of the channel floor, followed by deposition and episodic erosion of glaciolacustrine sediment in a high-energy, ice-proximal lake. Palaeoslope analysis confirms that the early Holocene low-water phase of Lake Ontario resulted in the development of a fluvial system in part of the channel. Water level was controlled by a sill at Kingston. Kingston basin, the Bay of Quinte, and possibly, for a short time, a much larger area of the upper Great Lakes drained through the channel. However, for most of the period, until it was flooded by the rising waters of Lake Ontario, the channel was occupied by a small river on a wide floodplain or it was flanked by broad marshes.
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Srebro, Haim. "Historical cartographic materials as a source for international and cadastral boundary management in rivers." Proceedings of the ICA 1 (May 16, 2018): 1–18. http://dx.doi.org/10.5194/ica-proc-1-104-2018.
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International and cadastral boundaries are important for ensuring stable legal territorial matters.<br> This article deals with the long-term location and management of boundaries in rivers and the depiction of the rivers on cartographic materials. A few countries have agreed that the boundary will not follow changes in the river (like in the Mongolia-China Border Treaty), whereas most agree that the boundary will follow slow, natural and gradual changes in the river (like is stated in the Israel-Jordan Peace Treaty). The international boundary under the British Mandate between Palestine and Trans-Jordan in the Jordan and Yarmuk rivers was defined in 1922. The cadastral boundaries were defined in these rivers in the 1930s along the international boundary.<br> For more than 70 years, until the Israel-Jordan 1994 Peace Treaty, the rivers have changed their channels east and westward to distances up to hundreds of meters. During that period the mandatory boundaries in these rivers changed their political status to the armistice lines, the cease-fire lines, and to international boundaries between sovereign states.<br> These lines were usually delineated on topographic maps in the rivers, drawn by cartographers following contemporary map revision. During that entire period the cadastral boundaries were not changed in order to adapt them to the actual position of the rivers and to the delineated international boundaries.<br> Owing to large water works on both rivers, including the construction of dams and diversion channels in order to meet the increasing needs of the population on both sides, the water flow of the rivers decreased dramatically to less than one tenth of the original natural flow. The population today is more than ten times than it used to be under the British Mandate. The changes in the water channels during the last 20 years since the 1994 peace treaty are in the magnitude of 10 meters versus hundreds of meters in the past. In addition, intensive land cultivation adjacent to the river banks has stabilized them.<br> In 2000, due to the construction of a dam on the Yarmuk River, both sides jointly fixed coordinates of the relevant boundary line in the river according to the boundary delineation in the peace treaty.<br> The accumulated artificial changes along both rivers have cancelled their natural behavior and have influenced the changes in the river channels. This may justify an initiative to fix the boundary lines in both rivers by coordinates according to the peace treaty delimitation, enabling the cadastral boundaries to be fixed according to the fixed international boundary line.<br> The article analyzes boundary line management in changing rivers in light of development of the legal approach and practice from the time of the Romans until today. It analyzes the special case of the boundary line in the Jordan and Yarmuk rivers, and introduces a proposal for stabilizing this boundary line.<br> The research of the changes of these rivers is based on changes in the depiction of their channels on various kinds of maps and cartographic sources, produced through the last century by many producers. They include British, German, ANZAC, Israeli and Jordanian maps and charts. The cartographic materials include large scale field survey sheets and engineering charts from the 1920s, cadastral charts from the 1930s, topographic maps produced through the last century and orthophoto maps produced since the 1990s, including joint Israeli-Jordanian orthophoto and charts produced by the Joint Boundary Commission as part of the peace agreement and its implementation. The article includes a variety of cartographic examples.
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van der Deijl, Eveline Christien, Marcel van der Perk, and Hans Middelkoop. "Establishing a sediment budget in the newly created “Kleine Noordwaard” wetland area in the Rhine–Meuse delta." Earth Surface Dynamics 6, no. 1 (March 7, 2018): 187–201. http://dx.doi.org/10.5194/esurf-6-187-2018.
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Abstract. Many deltas are threatened by accelerated soil subsidence, sea-level rise, increasing river discharge, and sediment starvation. Effective delta restoration and effective river management require a thorough understanding of the mechanisms of sediment deposition, erosion, and their controls. Sediment dynamics has been studied at floodplains and marshes, but little is known about the sediment dynamics and budget of newly created wetlands. Here we take advantage of a recently opened tidal freshwater system to study both the mechanisms and controls of sediment deposition and erosion in newly created wetlands. We quantified both the magnitude and spatial patterns of sedimentation and erosion in a former polder area in which water and sediment have been reintroduced since 2008. Based on terrestrial and bathymetric elevation data, supplemented with field observations of the location and height of cut banks and the thickness of the newly deposited layer of sediment, we determined the sediment budget of the study area for the period 2008–2015. Deposition primarily took place in channels in the central part of the former polder area, whereas channels near the inlet and outlet of the area experienced considerable erosion. In the intertidal area, sand deposition especially takes place at low-lying locations close to the channels. Mud deposition typically occurs further away from the channels, but sediment is in general uniformly distributed over the intertidal area, due to the presence of topographic irregularities and micro-topographic flow paths. Marsh erosion does not significantly contribute to the total sediment budget, because wind wave formation is limited by the length of the fetch. Consecutive measurements of channel bathymetry show a decrease in erosion and deposition rates over time, but the overall results of this study indicate that the area functions as a sediment trap. The total contemporary sediment budget of the study area amounts to 35.7×103 m3 year−1, which corresponds to a net area-averaged deposition rate of 6.1 mm year−1. This is enough to compensate for the actual rates of sea-level rise and soil subsidence in the Netherlands.
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Clausen, Eric. "Interpreting Topographic Map Evidence Related to Northeast Nebraska Barbed Tributaries and Drainage Routes, USA." Journal of Geography and Geology 10, no. 2 (May 29, 2018): 66. http://dx.doi.org/10.5539/jgg.v10n2p66.
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Northeast Nebraska barbed tributaries include north-oriented streams flowing to the south-oriented Missouri River and south-oriented streams flowing to the north-oriented Missouri River tributaries. Detailed topographic maps were used to determine how these northeast Nebraska drainage routes originated. A giant south-oriented supra-glacial melt water river is interpreted to have sliced an ice-walled and bedrock-floored canyon into a decaying ice sheet’s surface where eastern South Dakota’s east-facing Missouri Escarpment and west-facing Prairie Coteau escarpment are now located and to have flowed from that canyon’s mouth across northeast Nebraska while South Dakota’s north-facing Pine Ridge Escarpment is interpreted to be the south wall of a large east-oriented valley that was eroded headward across immense southeast-oriented ice-marginal melt water floods which had originally flowed across northeast Nebraska. Prior to Missouri River valley headward erosion these two different immense melt water floods created and then flowed across a low relief and low gradient northeast Nebraska topographic surface. Present day northeast Nebraska topography developed when the deep south-oriented Missouri River valley and its south-oriented tributary valleys eroded headward into this low relief and low gradient topographic surface. As the deep Missouri River valley eroded headward it beheaded shallow south-oriented flood flow channels supplying water to new and actively eroding south-oriented Missouri River tributary valleys and water on north ends of the beheaded channels reversed flow direction to move toward the much deeper Missouri River valley. Water still moving in south directions adjacent to these reversed flow channels was then captured leading to development of south-oriented tributaries to the north-oriented streams.
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Laskowski, Jerzy. "The Elizabeth and Klebarski (Victoria) canals. The history and origin of the names – analysis of the sources." Masuro-Warmian Bulletin 296, no. 2 (July 5, 2017): 329–47. http://dx.doi.org/10.51974/kmw-134978.
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In the locality of Silice, there is an intersection of two channels. Such an original hydrotechnical object became a touristic peculiarity and is often mentioned on websites. From this information and data included in the tourist guidebook of the Purda municipality, it is indicated that two channels –Elizabeth and Victoria – cross each other. In relation to the sources mentioned, the channels’ names are derived from the names of daughters of Emperor William II. In relation to the fact that William II had six sons and only one daughter, the real derivation of these names should be explained. The reasons of the appearance of the channels in the region of Kośnia river. The article describes the circumstances of building channels in the years 1843-1846. Furthermore, the origin of the name of “Elizabeth Channel” has been revealed. Maps and source materials have been investigated to introduce the history of channels’ names as far as German and English administration are concerned.
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Varenov, Aleksandr, Anna Tarbeeva, Dmitriy Botavin, Nadezhda Mikhaylova, Leonid Turykin, and Aleksandra Chalova. "Channel processes of a small river heavily modified by human activities." E3S Web of Conferences 163 (2020): 06011. http://dx.doi.org/10.1051/e3sconf/202016306011.
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Widely-spread small rivers are very poorly studied in relation to channel processes. The influence of local factors, high sensitivity to human impact, close connection with basin processes, and relatively low rates of channel changes distinguish them from medium and large ones and make it necessary to form a special approach to studies. Based on collection of long-term maps and local residents’ interviews, we reconstructed the transformation of channels in the Kudma River basin (the Volga Upland) for the last 200 years. Based on the bank erosion monitoring during 2011-2019 the modern rates of channel changes were revealed. We found that significant human impact is associated with the artificial channels cutoffs and draining of ponds which led to channel incision of the Kudma and Ozerka Rivers in the middle reaches and the transformation of floodplain into terrace. Agriculture development caused siltation of the upper reaches of rivers. The rivers of the forested part of the basin experienced the least human changes. From 2011 to 2019 the maximum rates of bank erosion were found to be within range of 0.3 to 2.7 m/year and supposed to be driven by peak water discharge.
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Prieto, M. R., and F. Rojas. "Documentary evidence for changing climatic and anthropogenic influences on the Bermejo Wetland in Mendoza, Argentina, during the 16th–20th century." Climate of the Past 8, no. 3 (May 30, 2012): 951–61. http://dx.doi.org/10.5194/cp-8-951-2012.
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Abstract. This paper examines the processes underlying changes to the once-extensive Bermejo Wetland, east of the city of Mendoza, Argentina (32°55' S, 68°51' W). Historical documents and maps from the 16th to 20th century are used to reconstruct environmental shifts. Historical documents indicate periods of increased snowfall in the adjacent Andes mountains, as well as high flow volumes in the Mendoza River. Data from georeferenced maps, the first from 1802 and the last from 1903, reflect the changes in the surface area of the wetland. The combined data sets show pulses of growth and retraction, in which major expansions coincided with more intense snowstorms and increased flow in the Mendoza River, which in turn influenced socio-economic activities. The wetland became progressively drier during the 19th century, before drying up completely around 1930, due in part to the construction of drainages and channels.
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Clausen, Eric. "Using Map Interpretation Techniques for Relative Dating to Determine a Western North Dakota and South Dakota Drainage Basin Formation Sequence, Missouri River Drainage Basin, USA." Journal of Geography and Geology 9, no. 4 (November 8, 2017): 1. http://dx.doi.org/10.5539/jgg.v9n4p1.
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Map interpretation techniques are used to determine the sequence in which western North and South Dakota erosion events occurred. The map interpretation techniques apply the principle of cross cutting relationships by studying asymmetric drainage divides, barbed tributaries, elbows of capture, drainage divide crossings, abandoned headcuts, and similar features on detailed topographic maps to determine the sequence in which drainage basins and valleys within those drainage basins formed. Detailed topographic maps covering western North and South Dakota show numerous closely spaced divide crossings along drainage divides separating the White, Bad, Cheyenne, Moreau, Grand, Cannonball, Heart, Knife, and Little Missouri Rivers. These divide crossings often form links between opposing northwest- and southeast-oriented tributary stream valleys and provide evidence of multiple closely spaced southeast-oriented flow channels that existed prior to formation of the deeper present day east-, northeast-, and north-oriented river valleys. Numerous barbed tributaries in the form of northwest-oriented tributaries to east- and northeast-oriented rivers (and major tributaries to the mentioned rivers) and southeast-oriented tributaries to the northeast- and north-oriented rivers (and tributaries to the mentioned rivers) suggest the deeper river (and tributary) valleys eroded headward across the southeast-oriented flow channels. Asymmetric drainage divides, barbed tributaries, abandoned headcuts, and elbows of capture demonstrate the southeast-oriented flow, which was most likely in the form of floods of ice-marginal melt water moving between the Black Hills uplift and a continental ice sheet’s southwest margin, was captured in sequence by headward erosion of the White, Bad, Cheyenne, Moreau, Grand, Cannonball, Heart, Knife, and Little Missouri River valleys. This erosion event sequence and its probable cause, determined from the map evidence, has major implications related to what is commonly considered to have been a much larger pre-glacial Bell River system, which included segments of each of the studied river valleys, and for all geologic and glacial history interpretations based on a Bell River system pre-glacial age interpretation.
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Silva, Sérgio Rui, Sérgio Cunha, Aníbal Matos, and Nuno Cruz. "Shallow Water Surveying Using Experimental Interferometric Synthetic Aperture Sonar." Marine Technology Society Journal 43, no. 1 (March 1, 2009): 50–63. http://dx.doi.org/10.4031/mtsj.43.1.4.
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AbstractThis paper describes an interferometric synthetic aperture sonar system based on an unmanned surface vehicle customized for shallow water environments. Synthetic aperture sonar enables imagery of high resolution that is independent of range by using the displacement of the sonar platform to create a large virtual array. If two geometrically displaced images are obtained, the construction of three-dimensional topographic maps is possible through the use of interferometric techniques. The use of an unmanned surface vehicle presents several advantages that alleviate some problems related to the formation of synthetic aperture images, which are mainly related to the fact that a precise navigation system can be used for the boat control and sonar imagery motion compensation. Also, a small unmanned surface vehicle is advantageous in terms of cost of operation, maintenance and ease of deployment. Mapping of shallow water areas is an important task for many commercial and scientific applications like river navigability, infrastructure maintenance and natural resource monitoring. These tasks can be done efficiently with this system. Sample data obtained during test trials illustrate how synthetic aperture can be used to generate underwater imagery and bathymetric data.
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Leuven, Jasper R. F. W., Sanja Selaković, and Maarten G. Kleinhans. "Morphology of bar-built estuaries: empirical relation between planform shape and depth distribution." Earth Surface Dynamics 6, no. 3 (September 11, 2018): 763–78. http://dx.doi.org/10.5194/esurf-6-763-2018.
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Abstract. Fluvial–tidal transitions in estuaries are used as major shipping fairways and are characterised by complex bar and channel patterns with a large biodiversity. Habitat suitability assessment and the study of interactions between morphology and ecology therefore require bathymetric data. While imagery offers data of planform estuary dimensions, only for a few natural estuaries are bathymetries available. Here we study the empirical relation between along-channel planform geometry, obtained as the outline from imagery, and hypsometry, which characterises the distribution of along-channel and cross-channel bed levels. We fitted the original function of Strahler (1952) to bathymetric data along four natural estuaries. Comparison to planform estuary shape shows that hypsometry is concave at narrow sections with large channels, while complex bar morphology results in more convex hypsometry. We found an empirical relation between the hypsometric function shape and the degree to which the estuary width deviates from an ideal convergent estuary, which is calculated from river width and mouth width. This implies that the occurring bed-level distributions depend on inherited Holocene topography and lithology. Our new empirical function predicts hypsometry and along-channel variation in intertidal and subtidal width. A combination with the tidal amplitude allows for an estimate of inundation duration. The validation of the results on available bathymetry shows that predictions of intertidal and subtidal area are accurate within a factor of 2 for estuaries of different size and character. Locations with major human influence deviate from the general trends because dredging, dumping, land reclamation and other engineering measures cause local deviations from the expected bed-level distributions. The bathymetry predictor can be used to characterise and predict estuarine subtidal and intertidal morphology in data-poor environments.
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Chen, Peng Xiao, Shao Hong Shen, and Xiong Fei Wen. "Remote Sensing Dynamic Monitoring on Illegal Capacity Occupation of Reservoir." Advanced Materials Research 718-720 (July 2013): 1124–28. http://dx.doi.org/10.4028/www.scientific.net/amr.718-720.1124.
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Monitoring the illegally occupied channels is very important for the management and regulations of reservoirs. This paper proposes an automatic and efficient approach to identify the changes in the river course with geographic information system and global position system using multi-temporal remote sensing images. Unlike the traditional river course monitoring system, this approach is mainly based on the change detection information extracting from multi-temporal high spatial resolution remote sensing images. Firstly, change detection from different information of multi-temporal remote sensing images are applied to obtain the change information thematic maps which can be used as working maps for on-site investigation are extracted. Secondly, GPS-RTK measurement technology is used to obtain 3-D position information of the terrain features points in those channel occupied areas. Then, an approach for calculating the volume of the channel occupied area is designed and developed by ArcGIS software using multi-temporal remote sensing images, 3-D position information and historical digital terrain date of channel occupied area. Finally, channel occupied area volume data and thematic maps are acquired by ArcGIS software. The data of reservoir is selected as experimental area, and the experiments have confirmed the high efficiency and accuracy of this approach proposed in this paper.
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Magliulo, Paolo, and Alessio Valente. "GIS-Based Geomorphological Map of the Calore River Floodplain Near Benevento (Southern Italy) Overflooded by the 15th October 2015 Event." Water 12, no. 1 (January 3, 2020): 148. http://dx.doi.org/10.3390/w12010148.
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On 15 October 2015, the floodplain of the Calore River underwent a destructive flood, with a stream stage increase up to 10 m. In this paper, we describe the GIS-based, object-oriented geomorphological map of the overflooded sectors of the Calore River floodplain near Benevento. The map graphically represents the field-checked results of a detailed geomorphological study carried out by means of GIS analysis of historical and topographic maps and orthophotos. Particular attention was devoted to the analysis of the channel adjustments experienced by the Calore River since the end of the 19th century, which shaped most of the landforms in the floodplain. The results showed that the investigated floodplain is characterized by abandoned channels, anthropogenic landforms, and five orders of recent river terraces separated by gently-sloping inactive fluvial scarps, less than 2 m high. On the oldest and/or more distal sectors of the floodplain, landforms are badly preserved, probably due to the more prolonged reshaping by natural erosional processes and anthropogenic activities, and to the high erodibility of the loose sediments in which they are shaped. The proposed map could be a key tool for a correct flood hazard assessment in the Benevento area, permitting thematic maps that avoid or reduce the negative effects of events similar to the 15 October 2015 flood.
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Daniell, James, Thomas Manoy, Robin J. Beaman, Jody M. Webster, and Ángel Puga-Bernabéu. "Shelf-edge delta and reef development on a mixed siliciclastic–carbonate margin, central Great Barrier Reef." Journal of Sedimentary Research 90, no. 10 (October 1, 2020): 1286–304. http://dx.doi.org/10.2110/jsr.2020.61.
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ABSTRACT The Great Barrier Reef (GBR) is the world's largest extant mixed silicilastic–carbonate margin. Previous research on the Great Barrier Reef has suggested that the extensive barrier reef system may act as an impermeable barrier and limit the development of delta systems during lowstands, but sufficient geophysical data to support this hypothesis are lacking. We use dense sparker seismic and sub-bottom profiler data to better understand the structure of a large lobe-shaped feature (∼ 10 km × 10 km) on the shelf edge of the central GBR and the interactions between siliciclastic and carbonate sedimentary systems. Interpreted sparker seismic contains prograding clinoforms and suggest that the lobe-shaped feature was a river-dominated shelf-edge delta. A delta on the shelf edge implies that the presence of an exposed barrier reef was not a major impediment to deposition and that other adjacent lobe-shaped features are also deltaic deposits. The shelf-edge deltas were deposited onto a broad upper-slope terrace that allowed continued progradation and limited incision when sea level fell below the shelf edge. Delta foresets are commonly colonized by coral reefs, but the spatial and temporal relationship between reefs and some deltaic units remains unclear. The presence of multiple shelf-edge deltas that link to previously mapped Burdekin River paleo-channels indicates a complex history of sedimentation, with the Burdekin River delta migrating up to 100 km along the GBR margin during the late Quaternary. Regional bathymetric data suggest that large modern or recent shelf-edge deltas are rare on the GBR and that there was a broad range of sedimentary processes operating along the margin of the GBR during periods of low sea level.
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Pour, A. B., and M. Hashim. "GEOLOGICAL FEATURES MAPPING USING PALSAR-2 DATA IN KELANTAN RIVER BASIN, PENINSULAR MALAYSIA." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W1 (September 29, 2016): 65–70. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w1-65-2016.
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In this study, the recently launched Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) onboard the Advanced Land Observing Satellite-2 (ALOS-2), remote sensing data were used to map geologic structural and topographical features in the Kelantan river basin for identification of high potential risk and susceptible zones for landslides and flooding areas. A ScanSAR and two fine mode dual polarization level 3.1 images cover Kelantan state were processed for comprehensive analysis of major geological structures and detailed characterizations of lineaments, drainage patterns and lithology at both regional and district scales. Red-Green-Blue (RGB) colour-composite was applied to different polarization channels of PALSAR-2 data to extract variety of geological information. Directional convolution filters were applied to the data for identifying linear features in particular directions and edge enhancement in the spatial domain. Results derived from ScanSAR image indicate that lineament occurrence at regional scale was mainly linked to the N-S trending of the Bentong-Raub Suture Zone (BRSZ) in the west and Lebir Fault Zone in the east of the Kelantan state. Combination of different polarization channels produced image maps contain important information related to water bodies, wetlands and lithological units for the Kelantan state using fine mode observation data. The N-S, NE-SW and NNE-SSW lineament trends were identified in the study area using directional filtering. Dendritic, sub-dendritic and rectangular drainage patterns were detected in the Kelantan river basin. The analysis of field investigations data indicate that many of flooded areas were associated with high potential risk zones for hydro-geological hazards such as wetlands, urban areas, floodplain scroll, meander bend, dendritic and sub-dendritic drainage patterns, which are located in flat topograghy regions. Numerous landslide points were located in rectangular drainage system that associated with topographic slope of metamorphic and Quaternary rock units. Some large landslides were associated with N-S, NNE-SSW and NE-SW trending fault zones. Consequently, structural and topographical geology maps were produced for Kelantan river basin using PALSAR-2 data, which could be broadly applicable for landslide hazard mapping and identification of high potential risk zone for hydro-geological hazards.
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Hutorowicz, Andrzej. "A Retrospective Ecological Status Assessment of the Lakes Based on Historical and Current Maps of Submerged Vegetation—A Case Study from Five Stratified Lakes in Poland." Water 12, no. 9 (September 18, 2020): 2607. http://dx.doi.org/10.3390/w12092607.
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This article presents and tests a new method for the retrospective assessment of ecological status assessment of the lakes in accordance with the Ecological State Macophyte Index (ESMI), which is formally used in biological monitoring in Poland. The proposed method is based on three metrics, the Z colonization index, the average maximum depth of lake vegetation Cmax, and the Secchi disk depth. Mathematical functions of ecological class were developed on the basis of the mean values of these three indicators in summer for different ecological status classes in 88 stratified lakes in northern Poland and the Łęczyńsko-Włodawskie Lake District and five lakes in the catchment area of the Wel River (published data). The new metrics were validated on the basis of literature data—ESMI, Cmax, Z and SD values from 11 lakes near Olsztyn (Poland). The obtained results are similar to those calculated based on macrophyte field surveys and can be an alternative of the Ecological State Macophyte Index (ESMI), which is formally used in biological monitoring in Poland. The proposed method makes it possible to compare long-term changes in the ecological state of lakes, because it enables an analogous assessment on the basis of data calculated from historical bathymetric maps showing the distribution of hydro macrophytes (parameters Z and Cmax) as well as contemporary data, collected, among others, during hydroacoustic research.
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Hanief, Aslam, and Andrew Laursen. "Modeling the Natural Drainage Network of the Grand River in Southern Ontario: Agriculture May Increase Total Channel Length of Low-Order Streams." Geosciences 9, no. 1 (January 17, 2019): 46. http://dx.doi.org/10.3390/geosciences9010046.
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The Grand River watershed is an important agricultural area in southern Ontario, with several large and growing municipalities. Based on digital elevation models (DEMs), the natural drainage network was modelled to predict flow paths. Channel lengths and locations of the predicted network were compared with a ground-truthed channel network to determine efficacy of the models. Approximately 5% of predicted channels lay >40 m from actual channel locations. This amounted to 388 km of channel that had no corresponding channels in reality. The model was unable to predict, based on topography, 2535 km of actual channel present in the watershed. Channels not anticipated by topography were mostly first-order, with low sinuosity, were most common in areas with high agricultural land use, and are likely excavated extensions to headwater streams to facilitate drainage. In addition, this study showed that Soil and Water Assessment Tool (SWAT) models produced using different DEM resolutions did not predict significantly different stream flows, even when resolution was as low as 200 m. However, these low resolution DEMs did result in under-prediction of sediment export entering Lake Erie, most likely because the low resolution maps failed to account for small localized areas of high slope that would have relatively higher rates of erosion.
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Laguta, Andrey, and Anatoly Pogorelov. "Analysis of silting and hydrodynamic processes in the degrading floodplain-valley reservoir (on the example of the Krasnodar Reservoir)." InterCarto. InterGIS 26, no. 2 (2020): 335–48. http://dx.doi.org/10.35595/2414-9179-2020-2-26-335-348.
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Based on the data of bathymetric surveys, topographic maps, and satellite images, the article analyzes sediment deposition processes in the bowl of the floodplain-valley Krasnodar Reservoir in connection with the circulation of water masses. Over the period of operation since 1973, the area of the Krasnodar reservoir decreased by 35 % with a significant decrease in usable volume. Particular attention is paid to the analysis of water circulation — the most important factor in the formation of the siltation body, processing of coasts and distribution of sediments. The average annual siltation of the Krasnodar Reservoir for 2005–2016 estimated at 6.9 mn m3. The greatest increase in the thickness of the siltation body (4–8 m or more) was recorded in the estuarine areas of the largest rivers flowing into the reservoir — within the estuary of the Kuban river and the Belaya river delta. In general, the formation of deltas plays a key role in the transformation of the reservoir. The upcoming Kuban delta from 1977–2018 occupied an area of 41.41 km2 in the water area of the reservoir, and the extension deltas formed by the Belaya river currently have a total area of 25.22 km2. The circulation of water masses was studied using an acoustic Doppler profilograph. Bowl transformation mechanisms and sediment deposition features are considered in the aspect of the movement of water masses in connection with the river flow and wind components of the circulation, as well as hydrodynamics at the mouth of the Kuban. It has been established that in the transverse profile in the reservoir there are two multidirectional flows. The main one is the right flow, formed under the influence of the Kuban runoff and the discharge of water from the reservoir, with a direction to the south-west (along the northern coast) and an average speed of 0.04 m/s; the left flow at an average speed of 0.01 m/s is directed east. Flow rates decrease with approach to the circulation axis.
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Hocini, Nabil, Olivier Payrastre, François Bourgin, Eric Gaume, Philippe Davy, Dimitri Lague, Lea Poinsignon, and Frederic Pons. "Performance of automated methods for flash flood inundation mapping: a comparison of a digital terrain model (DTM) filling and two hydrodynamic methods." Hydrology and Earth System Sciences 25, no. 6 (June 3, 2021): 2979–95. http://dx.doi.org/10.5194/hess-25-2979-2021.
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Abstract. Flash floods observed in headwater catchments often cause catastrophic material and human damage worldwide. Considering the large number of small watercourses possibly affected, the use of automated methods for flood inundation mapping at a regional scale can be of great help for the identification of threatened areas and the prediction of potential impacts of these floods. An application of three mapping methods of increasing level of complexity is presented herein, including a digital terrain model (DTM) filling approach (height above nearest drainage/Manning–Strickler or HAND/MS) and two hydrodynamic methods (caRtino 1D and Floodos 2D). These methods are used to estimate the flooded areas of three major flash floods observed during the last 10 years in southeastern France, i.e., the 15 June 2010 flooding of the Argens river and its tributaries (585 km of river reaches), the 3 October 2015 flooding of small coastal rivers of the French Riviera (131 km of river reaches) and the 15 October 2018 flooding of the Aude river and its tributaries (561 km of river reaches). The common features of the three mapping approaches are their high level of automation, their application based on a high-resolution (5 m) DTM, and their reasonable computation times. Hydraulic simulations are run in steady-state regime, based on peak discharges estimated using a rainfall–runoff model preliminarily adjusted for each event. The simulation results are compared with the reported flood extent maps and the high water level marks. A clear grading of the tested methods is revealed, illustrating some limits of the HAND/MS approach and an overall better performance of hydraulic models which solve the shallow water equations. With these methods, a good retrieval of the inundated areas is illustrated by critical success index (CSI) median values close to 80 %, and the errors on water levels remain mostly below 80 cm for the 2D Floodos approach. The most important remaining errors are related to limits of the DTM, such as the lack of bathymetric information, uncertainties on embankment elevation, and possible bridge blockages not accounted for in the models.
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O'Grady, D., M. Leblanc, and D. Gillieson. "Use of ENVISAT ASAR Global Monitoring Mode to complement optical data in the mapping of rapid broad-scale flooding in Pakistan." Hydrology and Earth System Sciences 15, no. 11 (November 17, 2011): 3475–94. http://dx.doi.org/10.5194/hess-15-3475-2011.
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Abstract. Envisat ASAR Global Monitoring Mode (GM) data are used to produce maps of the extent of the flooding in Pakistan which are made available to the rapid response effort within 24 h of acquisition. The high temporal frequency and independence of the data from cloud-free skies makes GM data a viable tool for mapping flood waters during those periods where optical satellite data are unavailable, which may be crucial to rapid response disaster planning, where thousands of lives are affected. Image differencing techniques are used, with pre-flood baseline image backscatter values being deducted from target values to eliminate regions with a permanent flood-like radar response due to volume scattering and attenuation, and to highlight the low response caused by specular reflection by open flood water. The effect of local incidence angle on the received signal is mitigated by ensuring that the deducted image is acquired from the same orbit track as the target image. Poor separability of the water class with land in areas beyond the river channels is tackled using a region-growing algorithm which seeks threshold-conformance from seed pixels at the center of the river channels. The resultant mapped extents are tested against MODIS SWIR data where available, with encouraging results.
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O'Grady, D., M. Leblanc, and D. Gillieson. "Use of ENVISAT ASAR Global Monitoring Mode to complement optical data in the mapping of rapid broad-scale flooding in Pakistan." Hydrology and Earth System Sciences Discussions 8, no. 3 (June 20, 2011): 5769–809. http://dx.doi.org/10.5194/hessd-8-5769-2011.
Full textAbstract:
Abstract. Envisat ASAR Global Monitoring Mode (GM) data are used to produce maps of the extent of the flooding in Pakistan which are made available to the rapid response effort within 24 h of acquisition. The high temporal frequency and independence of the data from cloud-free skies makes GM data a viable tool for mapping flood waters during those periods where optical satellite data is unavailable, which may be crucial to rapid response disaster planning, where thousands of lives are affected. Image differencing techniques are used, with pre-flood baseline image backscatter values being deducted from target values to eliminate regions with a permanent flood-like radar response due to volume scattering and attenuation, and to highlight the low response caused by specular reflection by open flood water. The effect of local incidence angle on the received signal is mitigated by ensuring that the deducted image is acquired from the same orbit track as the target image. Poor separability of the water class with land in areas beyond the river channels is tackled using a region-growing algorithm which seeks threshold-conformance from seed pixels at the center of the river channels. The resultant mapped extents are tested against MODIS SWIR data where available, with encouraging results.