scholarly journals CONDITIONING FACTORS OF “TERRAS CAÍDAS” IN LOWER SOLIMÕES RIVER - BRAZIL

2021 ◽  
Vol 22 (80) ◽  
pp. 220-233
Author(s):  
Matheus Silveira De Queiroz ◽  
Neiliane de Sousa Alves
Keyword(s):  
Wind Direction ◽  
Water Discharge ◽  
Suspended Sediments ◽  
Unconsolidated Sediments ◽  
Mass Movements ◽  
Causal Process ◽  
Conditioning Factors ◽  
The Stability ◽  
Moderate Scale ◽  
Solimões River

The term “Terras Caídas” is used in Amazon to refer to processes of fluvial erosion and mass movements of large and moderate scale. It is a dynamic and complex multi-causal process that involves hydrodynamic, hydrostatic, climatic, neotectonic, lithological and anthropic factors, occurring together or separately. The objective of this work is to understand the conditioning factors of the phenomenon "Terras Caídas" in lower Solimões River - Brazil. For this purpose, the study area was monitored for 2 years (2017-2018) and data from satellite images; water discharge; flow velocity; suspended sediments; water level; precipitation; wind direction; seismic activity were obtained. The hydrodynamic factors and the rain influence the “Terras Caídas” more intensely during the river flood, the processes influenced by the wind direction occur throughout the hydrological year, but with greater intensity during storms. Hydrostatic pressure occurs more frequently in ebb causing landslides. The lithology influences the stability of the banks due to unconsolidated sediments, providing erosion and mass movements. It is observed that neotectonics was not important in increasing the intensity of the "Terras Caídas" in the study area in recent years. Human activity influences destroying riparian forests and the basal erosion caused by waves formed by boats the region.

A new approach to the stability analysis of thawing slopes

1980 ◽  
Vol 17 (4) ◽  
pp. 607-612 ◽  
Author(s):  
Luis E. Vallejo
Keyword(s):  
Stability Analysis ◽  
Water Content ◽  
Pore Water ◽  
Active Layer ◽  
Necessary Conditions ◽  
Mass Movements ◽  
New Approach ◽  
Pore Water Pressures ◽  
The Stability ◽  
Excess Pore

A new approach to the stability analysis of thawing slopes at shallow depths, taking into consideration their structure (this being a mixture of hard crumbs of soil and a fluid matrix), is presented. The new approach explains shallow mass movements such as skin flows and tongues of bimodal flows, which usually take place on very low slope inclinations independently of excess pore water pressures or increased water content in the active layer, which are necessary conditions in the methods available to date to explain these movements.

scholarly journals Condicionantes geomorfológicos e da cobertura da terra na ocorrência de movimentos de massa na região serrana do Rio de Janeiro / Geomorphological and cover land conditioning factors of the mass movements in the mountainous region of Rio de Janeiro

2019 ◽  
Vol 29 (56) ◽  
pp. 27 ◽  
Author(s):  
Cristiane Nunes Francisco ◽  
Raquel Conceição Carvalho ◽  
Carla Maciel Salgado
Keyword(s):  
Land Cover ◽  
Rio De Janeiro ◽  
Landscape Evolution ◽  
Southeastern Brazil ◽  
Economic Losses ◽  
Mass Movements ◽  
Mountainous Region ◽  
Conditioning Factors ◽  
Different Types ◽  
Morphological Variables

Movimentos de massa são processos de evolução da paisagem condicionados por fatores geológicos, geomorfológicos, hidrológicos, climáticos e da cobertura vegetal. A região Sudeste do Brasil destaca-se pela ocorrência de eventos catastróficos, pois combina a ocupação das encostas com as características fisiográficas que a deixam altamente suscetível a diferentes tipos de movimentos de massa, destacando-se os escorregamentos translacionais. Embora tenham um importante papel na evolução da paisagem, a ocorrência de movimentos de massa em áreas ocupadas por atividades antrópicas tem gerado inúmeras perdas humanas e prejuízos econômicos. Foi o que ocorreu em janeiro de 2011 na região serrana do Rio de Janeiro, atingida por fortes chuvas que desencadearam eventos de extrema magnitude, e provocaram, além de destruição e morte, marcas profundas (cicatrizes) na paisagem que podem auxiliar no estudo dos processos de movimentos de massa. Este trabalho, assim, tem como objetivo analisar as relações espaciais entre a morfologia das encostas e a cobertura da terra com a ocorrência dos movimentos de massa em janeiro de 2011 na região serrana fluminense. Para tanto, foi realizado um estudo na bacia do rio Roncador, Nova Friburgo (Estado do Rio de Janeiro), com a sobreposição entre o mapeamento das cicatrizes, das variáveis morfológicas das encostas e das classes de cobertura da terra. Os resultados mostram que as cicatrizes predominaram em encostas de forma côncava e íngremes, além de cobertas por vegetação densa, corroborando com a literatura que aponta a declividade e a forma da encosta como fatores condicionantes significativos à ocorrência de movimentos de massa, em especial, dos escorregamentos translacionais.Palavras–chave: escorregamentos translacionais, corridas de lama, sistema de informação geográfica, desastre natural.Abstract Mass movements are landscape evolution processes conditioned by geological, geomorphological, hydrological, climatological and land cover factors. Southeastern Brazil is distinguished by the occurrence of catastrophic landslides events, due to the association of land use and physiographic factors which cause high susceptibility to the occurrence of different types of mass movements, mainly translational slides. Although mass movements have an important role in landscape evolution, their occurrence in areas occupied by human activities has generated numerous life human and economic losses. The mountainous region of Rio de Janeiro, in January 2011, was affected by rainstorms that caused the occurrence of extreme magnitude landslide events, which caused destruction and death as well as deep scars in the landscape, which can contribute to the study of mass movements processes. This paper aims to analyse the spatial relationships between the morphology of the slopes, the land cover and the occurrence of mass movements in January 2011 in the mountainous region of Rio de Janeiro. The study was performed in the Roncador river basin, Nova Friburgo municipality, by overlaying the spatial distribution of landslide scars with morphological variables of the slopes and land cover classes. The results show that the scars predominated on steep and concave slopes covered by dense vegetation, which corroborates the literature that indicates the slope and the curvature as a significant conditioning factor to the occurrence of mass movements, in particular, the translational slides.Keywords: translational slides, mudflows, geographic information system, natural disaster.

scholarly journals Automatic Monitoring System Designed for Controlling the Stability of Underground Excavation

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Piotr MAŁKOWSKI ◽  
Zbigniew NIEDBALSKI ◽  
Łukasz BEDNAREK
Keyword(s):  
Rock Mass ◽  
Underground Mining ◽  
Automatic Monitoring ◽  
Mass Movements ◽  
Support Design ◽  
Automatic Monitoring System ◽  
Underground Workings ◽  
The Stability ◽  
Technical Solutions ◽  
The Given

Ensuring the stability of mining excavations is a crucial aspect of underground mining. For thispurpose, appropriate shapes, dimensions, and support of workings are designed for the given mining andgeological conditions. However, for the proper assessment of the adequacy of the used technical solutions,and the calibration of the models used in the support design, it is necessary to monitor the behavior of theexcavation. It should apply to the rock mass and the support. The paper presents the automatic systemdesigned for underground workings monitoring, and the example of its use in the heading. Electronicdevices that measure the rock mass movements in the roof, the load on the standing support, and on bolts,the stress in the rock mass, are connected to the datalogger and can collect data for a long of time withoutany maintenance, also in hard-to-reach places. This feature enables the system to be widely used, inparticular, in excavations in the vicinity of exploitation, goafs, or in the area of a liquidated exploitationfield.

scholarly journals Suspended Sediment Variability at the Solimões and Negro Confluence between May 2013 and February 2014

Geosciences ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 265 ◽  
Author(s):  
Thiago Marinho ◽  
Naziano Filizola ◽  
Jean-Michel Martinez ◽  
Elisa Armijos ◽  
André Nascimento
Keyword(s):  
Suspended Sediment ◽  
Satellite Images ◽  
Suspended Sediments ◽  
Left Bank ◽  
Sediment Samples ◽  
Negro River ◽  
The World ◽  
The Right ◽  
Sediment Variability ◽  
Solimões River

This study focuses on the confluence of two major rivers of the world, the Solimões River (white waters) and Negro River (black waters). Surface suspended sediment samples (SSC) and spectroradiometer taken along transverse profiles at 500 m intervals over a distance of 10 km, as well as satellite images (MODIS) during the hydrological year, were used to follow suspended sediment variability. In January and February, the confluence is dominated by white waters from the Solimões River in the two banks, and in June and July in the right bank by black waters from the Negro River and in the left bank by clear waters from the Solimões River. We found that indirect tools, such as reflectance obtained by spectrometer or MODIS images, can be used to determine surface suspended sediments in a contrasting zone.

Theme lecture: Periglacial and slope processes

1991 ◽  
Vol 7 (1) ◽  
pp. 283-331 ◽  
Author(s):  
J. N. Hutchinson
Keyword(s):  
Ground Water ◽  
Late Quaternary ◽  
Water Discharge ◽  
Frost Heave ◽  
Mass Movements ◽  
Thaw Consolidation

AbstractFollowing a palaeoclimatic outline of the Late Quaternary, the paper reviews the periglacial and slope processes which have most effect on engineering works, particulary with regard to relic forms of such features in Britain. The first topics covered are; frost heave and thaw consolidation, thermokarst and periglacial mass movements, with particular attention to periglacial solifluction and slope development. Ground water discharge features, comprising pingos, anomalous depressions in the London Basin and perforated clay feather edges, are then discussed, as are superficial valley disturbances in various geological settings. The paper concludes by exploring theoretical and geological approaches to the determination of the former depths of permafrost in Britain.

Experimental Research on the Stability of Airflow in Diagonal Network during Fire

2013 ◽  
Vol 807-809 ◽  
pp. 2345-2350
Author(s):  
Wen Cai Wang ◽  
Bo Zhang ◽  
Wen Bin Wei ◽  
Yu Hong Jiang ◽  
Ya Chen Li ◽  
...  
Keyword(s):  
Wind Direction ◽  
Experimental Simulation ◽  
Diagonal Branch ◽  
Mine Fire ◽  
Tunnel Fire ◽  
Air Volume ◽  
Working Face ◽  
Air Supply ◽  
The Stability ◽  
Angle Connection

In order to study the influence of tunnel fire on the airflow stability in diagonal network of single diagonal network ventilation, according to the principle of similitude air supply system of 4101 working face of Huhewusu was taken for research object. In a proportion of 1:20, simulation device for angle connection roadway was established. By means of this simulation device and the method of experimental simulation, change law of the air volume and wind direction of diagonal branch in single diagonal network was studied. The results showed that in a particular period of mine fire, air volume decreased in fire roadway and windage increased; air volume in diagonal branch decreased and with the process of fire the wind direction would change. After the change of wind direction, with the changing of fire scale the reverse air volume would show the same changing process.

scholarly journals DESAIN SABO DAM TIPE CONDUIT SEBAGAI PENGENDALI DAYA RUSAK ALIRAN DEBRIS

2020 ◽  
Vol 16 (2) ◽  
pp. 105-116
Author(s):  
Yuli Fajarwati ◽  
Teuku Faisal Fathani ◽  
Fikri Faris ◽  
Wahyu Wilopo
Keyword(s):  
Rock Mass ◽  
Debris Flow ◽  
Return Period ◽  
Mass Movements ◽  
Flow Depth ◽  
Overturning Stability ◽  
Sediment Flow ◽  
The Stability ◽  
Building Stability ◽  
Flood Condition

ABSTRAKSungai Air Kotok di Kabupaten Lebong, Bengkulu memiliki litologi batuan yang rapuh akibat pengaruh panas bumi, kondisi tersebut menyebabkan rentan mengalami pergerakan massa tanah/batuan. Oleh karena itu, diperlukan upaya mitigasi untuk mengurangi risiko bencana dengan perencanaan bangunan pengendali aliran debris berupa sabo dam. Penelitian ini bertujuan untuk merencanakan desain sabo dam tipe conduit yang dirancang secara seri dan mengevaluasi stabilitas sabo dam berdasar SNI 2851:2015. Hasil perhitungan menunjukkan debit puncak untuk kala ulang 100 tahun sebesar 171,21 m3/detik. Empat seri sabo dam memiliki dimensi lebar pelimpah rerata ± 40 m, kedalaman aliran debris sebesar 1 m, dan tinggi pelimpah ialah 2,4 m. Stabilitas sabo dam saat banjir diperoleh faktor aman untuk stabilitas geser dan guling sebesar 3,46 ; 1,62. Adapun faktor aman terhadap pengaruh aliran debris untuk stabilitas geser dan guling adalah 3,30 ; 1,58. Berdasarkan hasil analisis, empat seri sabo dam tipe conduit yang dirancang mampu mengendalikan daya rusak banjir maupun aliran debris.Kata kunci: Hidraulika sungai, aliran sedimen, bangunan sabo, stabilitas sabo ABSTRACTAir Kotok River in Lebong Regency, Bengkulu Province has the lithology of weathered rock which is a result of geothermal process, this condition causes to be susceptible to land / rock mass movements. Therefore, the mitigation efforts are needed to reduce the risk from disaster by design debris flow control such as sabo dam. This study aims to design series of conduit type sabo dam and evaluate the stability based on SNI 2851: 2015. The calculation shows that the peak discharge for the 100-year return period is 171.21 m3 / sec. The four sabo dam series have dimensions of spill width of ± 40 m, debris flow depth of 1 m, and overflow height of 2.4 m. The stability of sabo dam has safety factor in flood condition for shear and overturning stability are 3.46; 1.62, while in a debris flow condition for shear and overturning stability are 3.30; 1.58. Based on the results, the four series of conduit sabo dam are able to control the destructive power of floods and debris flows.Key word: River hydraulic, sediment flow, sabo building, stability of sabo

Hydraulic Modelling of Suspended Sediment Deposition in an Inundated Floodplain of the Nemunas Delta

2003 ◽  
Vol 34 (5) ◽  
pp. 519-530 ◽  
Author(s):  
Saulius Vaikasas ◽  
Alfonsas Rimkus
Keyword(s):  
Suspended Sediment ◽  
Water Discharge ◽  
Alluvial Soil ◽  
Measurement Data ◽  
Thick Layer ◽  
Soil Surface ◽  
Suspended Sediments ◽  
Sediment Deposition ◽  
Curonian Lagoon ◽  
River Bank

Floods of meadows in the delta of the river Nemunas contribute to the deposition and retention of sediments and nutrient that would otherwise deposit in the Curonian Lagoon. In grassland area of the Nemunas delta the formation of alluvial soil occurs according to the flood dynamic rules: water discharging into the valley leaves suspended sediments on the soil surface. By mathematical modelling it was established that about 35% of suspended sediments inflow deposited there. Due to sand particles deposited during the study period (1950-1991), the natural river bank levee rose by 0.3 m. Fine clay and silt particles deposited uniformly within the entire model area and formed a 4-6 mm thick layer there. It contained about 50-60 t/ha of silt deposits. The valley soils were naturally fertilized with 250 t of potassium, 950 t of phosphorus, 38,000 t of calcium, and even 147,000 t of organic matter saturated with nitrogen. Certain amount of heavy metals also deposited there. The deposition process has not yet been adequately investigated under the conditions of flow bed covered by grass. It was established that grass cover intensified the sediment deposition in the floodplain. Considering calculation results and measurement data, the process of suspended sediment deposition was analysed and new formulas were derived. It was established that in order to increase sedimentation in the valley, it would be necessary to increase water discharge overflowing from river bed into the delta valley.

scholarly journals Vulnerability to geomorphological hazards of an Arctic cliff-nesting raptor, the rough-legged hawk

2017 ◽  
Vol 3 (2) ◽  
pp. 203-219 ◽  
Author(s):  
Andréanne Beardsell ◽  
Gilles Gauthier ◽  
Daniel Fortier ◽  
Jean-François Therrien ◽  
Joël Bêty
Keyword(s):  
Climate Change ◽  
Sedimentary Rocks ◽  
Unconsolidated Sediments ◽  
Mass Movements ◽  
Factors Associated ◽  
Temperature And Precipitation ◽  
Bylot Island ◽  
Geomorphological Processes ◽  
Steep Slopes ◽  
Buteo Lagopus

Increase in temperature and precipitation associated with climate change may enhance the risk of destruction by geomorphological processes of nests or dens used by Arctic wildlife. We assessed nest vulnerability to mass movements and identified environmental factors associated with the persistence of nesting structures of rough-legged hawks (Buteo lagopus), a species that typically nests on steep slopes or cliffs. The study was conducted on Bylot Island (Nunavut) where 82 permanent hawk nesting structures, built mainly on sedimentary rocks, were monitored from 2007 to 2015. More than a quarter of known nests were destroyed during the course of the study and among those still intact, more than half were associated with a moderate to high risk of being destroyed. Nest survival analysis suggested a relatively short persistence of rough-legged hawk nesting structures on Bylot Island compared to other Arctic cliff-nesting species. Nest destruction probability increased for nests built on unconsolidated sediments, with heavy rainfall and temperature during the summer. The anticipated increase in precipitation and temperature due to climate change is likely to augment the exposure of hawk nests to mass movements, which could ultimately reduce the availability of suitable sites for the reproduction of this Arctic-nesting raptor.

scholarly journals Decline of Fine Suspended Sediments in the Madeira River Basin (2003–2017)

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 514 ◽  
Author(s):  
Irma Ayes Rivera ◽  
Elisa Armijos Cardenas ◽  
Raúl Espinoza-Villar ◽  
Jhan Espinoza ◽  
Jorge Molina-Carpio ◽  
...  
Keyword(s):  
Suspended Sediment Concentration ◽  
Sediment Load ◽  
Water Discharge ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Hydropower Potential ◽  
Madeira River ◽  
Fine Suspended Sediment ◽  
Porto Velho ◽  
Madeira River Basin

The Madeira River is the second largest Amazon tributary, contributing up to 50% of the Amazon River’s sediment load. The Madeira has significant hydropower potential, which has started to be used by the Madeira Hydroelectric Complex (MHC), with two large dams along the middle stretch of the river. In this study, fine suspended sediment concentration (FSC) data were assessed downstream of the MHC at the Porto Velho gauging station and at the outlet of each tributary (Beni and Mamoré Rivers, upstream from the MHC), from 2003 to 2017. When comparing the pre-MHC (2003–2008) and post-MHC (2015–2017) periods, a 36% decrease in FSC was observed in the Beni River during the peak months of sediment load (December–March). At Porto Velho, a reduction of 30% was found, which responds to the Upper Madeira Basin and hydroelectric regulation. Concerning water discharge, no significant change occurred, indicating that a lower peak FSC cannot be explained by changes in the peak discharge months. However, lower FSCs are associated with a downward break in the overall time series registered at the outlet of the major sediment supplier—the Beni River—during 2010.

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