• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 31
  • 8
  • 2
  • 2
  • Tagged with
  • 44
  • 44
  • 27
  • 27
  • 11
  • 8
  • 7
  • 7
  • 7
  • 7
  • 6
  • 6
  • 6
  • 6
  • 6
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Estudos de movimentos de massa gravitacionais, processos erosivos e áreas sujeitas a inundações na área urbana de Antonina, Litoral do Paraná - Escala 1:10.000 / Studies of gravitational mass movements, erosive processes and flooded areas in the urban area of Antonina, coast of Paraná - Brazil

Rosângela Mara Tapia Lima 03 December 2001 (has links)
Apresentam-se neste trabalho os resultados obtidos no estudo de movimentos de massa gravitacionais, processos erosivos e áreas sujeitas a inundações na área urbana de Antonina, litoral do Paraná. Inicialmente são apresentadas as principais classificações e metodologias para a identificação dos processos de movimentos de massa gravitacionais, processos erosivos e áreas sujeitas a inundações e elaboração de documentos. Na área foram mapeadas 85 feições, entre movimentos de massa gravitacionais e feições erosivas com características geológico-geotécnicas diversas e também foram selecionadas áreas sujeitas a inundações. Os documentos cartográficos elaborados foram os seguintes: mapa altimétrico, mapa de documentação, mapa de bacias hidrográficas, mapa litológico, mapa de materiais inconsolidados, mapa de landforms, mapa de uso e ocupação do solo, mapa de feições de movimentos de massa gravitacionais e processos erosivos (inventário), carta de declividade, carta de direção preferencial de fluxo de águas superficiais. E por fim, a carta das áreas com alta predisposição aos movimentos de massa gravitacionais, aos processos erosivos e inundação, que apresenta a distribuição dos processos na área. Todos estes documentos foram elaborados na escala 1:10.000. / This research focuses on the gravitational mass movements, erosive processes and flooded areas in the urban area of Antonina, coast of Paraná, BraziI. The main classifications for the identification of gravitational mass movements and erosive processes as well as areas subject to floods and elaboration of documents are presented initially. In the area 85 features of erosion and gravitational mass movements with different geological-geotechnical characteristics were mapped and flooded zones were delimited. The cartographic documents elaborated are: topographical map, documentation map, hydrographic basin map, lithologic map, unconsolidated materials map, landform map, soil use and occupation map, gravitational mass movements and erosive processes features map (inventory map), slope chart and surface water flow chart. Finally the gravitational-mass movements, erosive processes and flooded predisposition zone high chart are presented with the distribution of the processes in the area studied. All these documents were elaborated at scale 1:10,000.
32

As características físicas, químicas, mineralógicas e hidráulicas do solo e sua susceptibilidade ao processo de terras caídas: Comunidade do Divino Espírito Santo Iranduba/AM

Magalhães, Regiane Campos 20 December 2011 (has links)
Made available in DSpace on 2015-04-11T13:57:30Z (GMT). No. of bitstreams: 1 DISSERTACAO REGIANE CAMPOS.pdf: 3390691 bytes, checksum: 83f083078c542a41b426ac59f8cb7b7c (MD5) Previous issue date: 2011-12-20 / Fundação de Amparo à Pesquisa do Estado do Amazonas / Large part of the soil is, constantly, mobilized from the margins to the inside of the Solimões River, actuated by the natural process of and involves physical and hydrological factors, coming to cause changes in the relief of the community Divino Espírito Santo, in Iranduba - AM. This work was aimed not only to analyze the process of earth falls in this community, through the extensive scars during the period July 2010 to September 2011, as well as describe variables physics, chemistry, mineralogical and soil hydraulic and monitor the fluviometry and pluviometry in the area. The methodology was based on a systemic approach, based on the following methodology: monitoring the scars lifting by ordenadas, piezometry, pluviometry, fluviometry, tests of infiltration, physical analysis, chemical, mineralogical and hydraulic soil (granulometric, organic matter, apparent density, real density, microporosity, macroporosity, total porosity, macronutrients, micronutrients, carbon and difratometry X-rays). The results of the study have led to the conclusion that earth falls, besides being a regional terminology, is a natural process that corresponds to different mass movements, mainly the rotational slip and block fall, acting in different periods of the river (flood and ebb). The occurrence of this process does not depend on the shape of the margins of the river and the type of geomorphological unit, because the main factor in determining the Earth Falls is the susceptibility of the soil, whose variables verified commanding the stability of ravine, thus generating different mass movements. / Grande parte dos solos é, constantemente, mobilizada das margens para dentro do rio Solimões, acionada pelo processo natural de Terras Caídas e envolve fatores físicos e hidrológicos, vindo a provocar mudanças no relevo da comunidade Divino Espírito Santo, em Iranduba AM. Esse trabalho teve por objetivo não somente analisar o processo de Terras Caídas desta comunidade, através das extensas cicatrizes durante o período de julho de 2010 a setembro de 2011, como também descrever as variáveis física, química, mineralógica e hidráulica do solo e monitorar a fluviometria e pluviometria da área. A metodologia fundamentou-se em uma abordagem sistêmica, baseada nos seguintes procedimentos metodológicos: monitoramento das cicatrizes - Levantamento por Ordenadas, piezometria, pluviometria, fluviometria, testes de infiltração, análises física, química, mineralógica e hidráulica do solo (granulométrica, matéria orgânica, densidade aparente, densidade real, microporosidade, macroporosidade, porosidade total, macronutrientes, micronutrientes, carbono e difratometria de Raios-X). Os resultados do estudo realizado permitiram concluir que a Terra Caída, além de ser uma terminologia regional, é um processo natural que corresponde a distintos movimentos de massa, principalmente o escorregamento rotacional e a queda em bloco, agindo em diferentes períodos do rio (cheia e vazante). A ocorrência desse processo independe da forma das margens do rio e do tipo de unidade geomorfológica, pois o principal fator para determinar as Terras Caídas é a susceptibilidade do solo, cujas variáveis verificadas comandam a estabilidade do barranco, gerando assim, distintos movimentos de massa.
33

Estudo dos movimentos gravitacionais de massa e processos erosivos com aplicação na área urbana de Ouro Preto (MG): escala 1:10.000 / not available

Teresinha de Jesus Bonuccelli 16 July 1999 (has links)
Apresenta-se nesse trabalho os resultados obtidos no estudo dos movimentos gravitacionais de massa e processos correlatos na área urbana de Ouro Preto - MG, na escala 1:10.000. Executou-se um levantamento e discussão dos diferentes tipos de processos que atuam em áreas urbanas e os atributos que podem influenciar na sua ocorrência; o inventário dos processos e levantamento dos atributos para Ouro Preto, assim como o cadastro das ocorrências atendidas pelo Corpo de Bombeiros relacionadas a esses fenômenos para o período de 1988 a 1998. As análises das relações atributos versus ocorrência de processos foi desenvolvida com utilização de técnicas semi-estatísticas e o emprego do sistema de informação geográfica ILWIS v.2.1. Concluiu-se que os principais tipos de processos que ocorrem na área urbana de Ouro Preto são classificados como complexos, escorregamentos e erosões, que se apresentam predominantemente ativos, com profundidades inferiores a 10 m. Os atributos predisponentes são principalmente a declividade e o substrato rochoso, sendo que o tipo de uso do solo e a pluviosidade são os principais fatores modificadores e deflagradores. / A study, and their results, of gravitational mass movements and related processes in Ouro Preto\'s urban area is presented at 1:10,000 scale. A research and discussion of processes types and intluential attributes is carried out. A inventory and a characterization of processes and attributes are executed for Ouro Preto, and also a survey of Civil Defense ocurrences during 1988-1998 period is elaborated. The relationships between attributes and processes types are analysed using semi-estatistcal techniques and geographic information system ILWIS v.2.1. The main processes types remarked are: complexes, landslides related, erosions related. The more frequently events are classifyed as active processes. The main depths noted are: shallow and medium, i e, below 10 meters. The main predisponent attributes are: declivity and bedrock, and the modifying and triggering attributes are: land use and pluviosity.
34

Zoneamento da susceptibilidade à ocorrência de escorregamentos na Bacia Hidrográfica do Córrego do Yung

Faria, Rosana Lino de 30 October 2013 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-20T20:17:35Z No. of bitstreams: 1 rosanalinodefaria.pdf: 11924423 bytes, checksum: 9bf208a80f5b796b7750aa9fa55c35d8 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-24T16:53:54Z (GMT) No. of bitstreams: 1 rosanalinodefaria.pdf: 11924423 bytes, checksum: 9bf208a80f5b796b7750aa9fa55c35d8 (MD5) / Made available in DSpace on 2017-04-24T16:53:54Z (GMT). No. of bitstreams: 1 rosanalinodefaria.pdf: 11924423 bytes, checksum: 9bf208a80f5b796b7750aa9fa55c35d8 (MD5) Previous issue date: 2013-10-30 / No Brasil, o estudo dos processos relacionados a movimentos de massa em áreas urbanas tem crescido devido ao elevado número de ocorrências e, muitas delas com vítimas fatais. Na cidade de Juiz de Fora, e em seu contexto a Bacia do Córrego do Yung, o crescimento do número de ocorrências de movimentos de massa está relacionado às características físicoambientais e à ocupação irregular das encostas. Para a predição desse tipo de processo inúmeras metodologias têm sido propostas no mundo científico, e dentre muitas, o modelo matemático determinístico SHALSTAB (Shallow Stability), tem se sobressaído por apresentar resultados muito bons em várias regiões do mundo, como EUA, Itália, Canadá, Brasil, dentre outros. A partir disso, o objetivo desse trabalho foi criar um Mapeamento de Risco a Movimentos de Massa na Bacia do Córrego do Yung através da análise da instabilidade à movimentos de massa e da análise do tipo de cobertura e uso da terra. Para isso foi necessário gerar um modelo digital de elevação, para obter os parâmetros geomorfológicos (declividade e área de contribuição), base para o mapeamento da susceptibilidade à movimentos de massa. Para o mapeamento da cobertura e uso da terra foi utilizada a cobertura aerofotogramétrica da área, fornecido pela Defesa Civil/PJF, onde se destacaram 6 classes de uso, dentre elas as áreas edificadas, as áreas com cobertura vegetal e as áreas referentes à corpos d’água. Os resultados apontaram que a Bacia do Córrego do Yung ainda se encontra em processo de urbanização, uma vez que apenas 12,2% da sua área se encontra edificada e outros 58,5% se encontra ocupada apenas por vegetação rasteira ou pastagem. Em relação à análise da instabilidade da bacia percebeu-se que grande parte das áreas classificadas com algum grau de instabilidade está localizada na porção sul e sudeste da bacia, região com alto índice de ocupação. Nesta análise verificou-se que 0,25 km2 ou 0,55% da área da bacia é considerada Instável pelo modelo SHALSTAB, dentro das quais foram mapeadas 47 das cicatrizes. Em relação ao Zoneamento de Risco a Movimentos de Massa percebeu-se que 0,02 km2 ou 0,10% da área total da bacia é considerada de altíssimo risco e que apenas 25,25% é considerada de baixo risco. Com base nesses resultados percebeu-se que o uso de modelos matemáticos para a previsão de movimentos de massa associado ao conhecimento da cobertura e uso da terra é uma ferramental fundamental para se mapear as condições de risco em áreas ocupadas em bacias hidrográficas. Espera-se que este estudo possa orientar pesquisas posteriores e auxiliar os diversos órgãos competentes na gestão de áreas de risco na cidade de Juiz de Fora. / In Brazil, the study of the processes related to the mass movements in urban areas has increased due to the high number of occurrences with fatal victims. In city of Juiz de Fora which belongs the Stream of Yung Basin, the growth of the occurrences of mass movements is related to the physical-environmental features and with the inappropriate occupancy of slopes. For the prediction of such type of process, several methods have been proposed in the scientific context. Among these, the determinist mathematical model SHALSTAB (Shallow Stability) deserves attention since it produces good results in several parts of world, like EUA, Italy, Canadian and Brazil. The aim of this work was to create a mapping of risk to mass movements in the Stream of Yung Basin by means an analysis of instability to the mass movements and an analysis of the type of coverage and use of earth. To obtain the mapping of risk, it was necessary to generate a digital model of elevation to get the geomorphologic parameters (declivity and area of contribution) which are the base of the mapping of susceptibility to the mass movements. For the mapping of coverage and use of earth, was used the aerophotogrammetric coverage of the area furnished by the Civil Defense/PJF highlighting six classes of use e.g., built-up areas, vegetal coverage area and areas related to water bodies. The results show that the Stream of Yung Basin is still in urbanization process, since only 12,2% of its area contains buildings, and 58,5% is occupied only by underwood or pasture. With respect to the analysis of instability of the basin, an extensive part of the areas classified with some grade of instability are located in the south and southeast of the basin, a region with a high index of occupation. The analysis show that 0,25 km2 or 0,55% of the basin area is considered unstable by the model SHALSTAB. It were mapped 47 of the scars.With respect to the risk zoning to the mass movements, 0,02 km2 or 0,10% of the total area of the basin is considered of very high risk to occupancy, and only 25,25% is considered as low risk. These results permit to conclude that the use of mathematical models associated to the knowing of the coverage and use of earth for predicting the mass movements is an important method to map the risk conditions in occupied areas in hydrographic basins. It is expected that this present work may serve as guidance for further researches as well as to help several competent public agents on management of areas of risk in the city of Juiz de Fora.
35

[pt] ANÁLISE DINÂMICA DE FLUXOS DE DETRITOS EM REGIÕES TROPICAIS / [en] DYNAMIC ANALYSIS OF DEBRIS FLOWS IN TROPICAL REGIONS

ANA MARÍA VALVERDE SANCHO 31 October 2016 (has links)
[pt] Os fluxos de detritos são perigosos riscos naturais, que afetam países com intensas precipitações e terrenos montanhosos. Tais eventos configuram alto perigo para a vida humana e danificação de infraestrutura, resultando em importantes perdas econômicas. O estudo de fluxos de detritos envolve um mecânismo complexo e suas técnicas de previsão são baseadas na calibração de modelos, que devem ser delimitados por tentativa e erro de eventos anteriores. Tais previsões são ferramentas valiosas para delimitar as potenciais áreas de risco e, dessa forma, projetar medidas de mitigação e convivência. O principal objetivo deste trabalho foi analisar o comportamento de quatro fluxos de detritos deflagrados por precipitações de alta intensidade em regiões tropicais utilizando modelagem numérica em 2D e 3D. Foram analisados os casos de Lajas e Llano de la Piedra na Costa Rica e os casos de Córrego D Antas e Hospital São Lucas no Rio de Janeiro. Os principais parâmetros utilizados, na avaliação do risco deste tipo de movimentos de massa, são: a distância percorrida, a área de impacto, a velocidade e profundidade do fluxo. Os casos foram calibrados utilizando a reologia de Voellmy. A definição dos parametros na calibração é vital, pois oferece a possibilidade de previsões de primeira ordem, feita sobre escorregamentos acontecendo em condições semelhantes. Os resultados da análise dinâmica mostram valores consistentes entre os valores observados e as modelagens numéricas em 2D e 3D para os principais parâmetros avaliados, corroborando o uso destas ferramentas para análises de risco e projeção de medidas de mitigação e convivência. / [en] Debris flows are dangerous natural hazards affecting countries with steep terrains and heavy rainfall. They are associated with serious risks to human lives and infrastructure leading to important economic losses and fatalities. Debris flows involve complex mechanics and prediction techniques that are based on the calibration of models that must be constrained by trial-and-error back-analysis of previous landslides. Such predictions are a valuable tool for outlining potential hazard areas and the development of mitigation strategies and design of protective structures. The main goal of this work was to analyze the behavior of four debris flows triggered by heavy rainfall in tropical regions with numerical modelling. The Voellmy rheology was used to calibrate the cases occurred in Lajas and Llano de la Piedra in Costa Rica, and Córrego D Antas and Hospital São Lucas in Rio de Janeiro. The main parameters used for landslide risk assessment are runout distance, potential impact area, flow velocity and flow depth. The definition of appropriate calibrating parameters is important because it provides the possibility of first order predictions to be made about the motion of future landslides happening under similar conditions. The results of the dynamic analysis showed that consistent values were obtained for the main parameters evaluated in the 2D and 3D runout models, verifying the usefulness of these tools for landslide risk assessment and the project of protection structures.
36

Ωκεανογραφικές - γεωμορφολογικές έρευνες στον κεντρικό Κορινθιακό κόλπο σε σχέση με την διασπορά μεταλλευτικών αποβλήτων ερυθράς ιλύος

Ιατρού, Μαργαρίτα 30 April 2014 (has links)
Ο Κορινθιακός κόλπος αποτελεί ένα φυσικό εργαστήριο για την παρακολούθηση ιζηματολογικών διεργασιών μεταφοράς ιζημάτων από το περιβάλλον της υφαλοκρηπίδα σε αυτό της λεκάνης. Η μορφολογία και η δομή του Κορινθιακού κόλπου φέρουν τα χαρακτηριστικά ενός ενεργού ηπειρωτικού περιθωρίου με βάθη από 100 μέχρι ~850 m όπου αναπτύσσονται ένα πλήθος διεργασιών που δρουν μεταβάλλοντας το ανάγλυφο και διαμορφώνουν το ιζηματογενές κάλυμμα. Στο βόρειο περιθώριο του Κεντρικού Κορινθιακού Κόλπου πραγματοποιείται από το 1970, η υποθαλάσσια έκχυση μεταλλευτικών απόβλητων που σχηματίζονται κατά την επεξεργασίας βωξίτη για την παραγωγή αλουμίνας. Τα μεταλλευτικά απόβλητα, γνωστά και ως ερυθρά ιλύς, απορρίπτονται στην υφαλοκρηπίδα του κόλπου της Αντίκυρας, στην βόρια ακτή του Κορινθιακού Κόλπου. Η παρούσα διδακτορική διατριβή διαπραγματεύεται το σημαντικό, για τον ελληνικό θαλάσσιο χώρο, περιβαλλοντικό θέμα της εξάπλωσης της βωξιτικής ερυθράς ιλύος στον Κεντρικό Κορινθιακό κόλπο. Ιδιαίτερη έμφαση δόθηκε στις διεργασίες διασποράς και μεταφοράς της ερυθράς ιλύος στην περιοχή έρευνας. Η μελέτη του θέματος της διατριβής στηρίχθηκε σε ένα ευρύ φάσμα πρωτογενών δεδομένων που συλλέχθηκαν από το Εργαστήριο Θαλάσσιας Γεωλογίας & Φυσικής Ωκεανογραφίας του Τμήματος Γεωλογίας, Πανεπιστήμιο Πατρών. Η συλλογή των δεδομένων πραγματοποιήθηκε σε τέσσερις χρονικές περιόδους από το 1994-2007. Κατά την διάρκεια των ωκεανογραφικών αποστολών εκτελέσθηκαν θαλάσσιες γεωφυσικές έρευνες με χρήση τομογράφου υποδομής πυθμένα και ηχοβολιστή πλευρικής σάρωσης, οπτικές παρατηρήσεις του πυθμένα με χρήση κατευθυνόμενου υποβρύχιου οχήματος και συλλέχθηκε ένας μεγάλος αριθμός δειγμάτων ιζήματος. Κατά την εκπόνηση της παρούσας διδακτορικής διατριβής εκτελέστηκαν μία σειρά αναλύσεων για τις φυσικές, χημικές και ορυκτολογικές ιδιότητες των δειγμάτων. Η επεξεργασία των γεωφυσικών δεδομένων οδήγησε στην λεπτομερή αποτύπωση της βαθυμετρίας και μορφολογίας της περιοχής έρευνας. Η κατωφέρεια του βόρειου περιθωρίου του Κορινθιακού Κόλπου διασχίζεται από πολυάριθμες χαραδρώσεις. Συνολικά αναγνωρίστηκαν είκοσι οκτώ (28) χαραδρώσεις. Δεκαεφτά (17) από αυτές αναπτύσσονται στην κατωφέρεια του Κόλπου της Αντίκυρας. Η ερυθρά ιλύς εκχύνεται στην υφαλοκρηπίδα του Κόλπου της Αντίκυρας διαμέσου ενός συστήματος υποβρύχιων αγωγών οι οποίοι τερματίζουν σε βάθος νερού 100-120 m. Το μεταλλευτικά απόβλητα αποτελούν ένα μείγμα λεπτόκοκκων υποπροϊόντων (ιλύς και λεπτόκοκκη άμμος) με θαλασσινό νερό που απορρίπτεται σε μορφή λάσπης στον πυθμένα της υφαλοκρηπίδας. Στην περιοχή εξόδου των αγωγών, στην υφαλοκρηπίδα, η ερυθρά ιλύς σχημάτισε συγκεντρώσεις σημαντικού πάχους. Μέχρι το 1994 σχηματίστηκαν τρεις υποθαλάσσιοι λοβοί. Ο λοβός Α, στα δυτικά, έχει μέγιστο ύψος 14 m. Ο κεντρικός λοβός Β έχει μέγιστο ύψος 27 m. Ο ανατολικός λοβός Γ έχει μέγιστο ύψος 23 m. Οι τρεις λοβοί συνενώνονται σε μία ενιαία λοβοειδή κύρια απόθεση. Η ερυθρά ιλύς διασπείρεται από την κύρια λοβοειδή απόθεση. Η οπτική διασκόπηση του πυθμένα έδειξε ότι προς τα ανάντη των λοβών οι υποβρύχιοι αγωγοί έχουν θαφτεί από ερυθρά ιλύ σε βάθος νερού ~53 m. Προς τα κατάντη η ερυθρά ιλύς διασπείρεται σε Ν-ΝΔ διεύθυνση. Δημιουργείται έτσι ένα επιφανειακό στρώμα ερυθράς ιλύος πάχους 27 έως 1 m, το οποίο αποτελεί την ευρύτερη απόθεση ερυθράς ιλύος. Δείγματα ιζήματος από την υφαλοκρηπίδα παρουσίασαν ότι ο πυθμένας καλύπτεται από ένα επιφανειακό στρώμα ερυθράς ιλύος ελάχιστου πάχους ενός εκατοστού. Επιπλέον υποβρύχιες εικόνες επιβεβαίωσαν την κάλυψη του φυσικού πυθμένα της υφαλοκρηπίδας από ένα λεπτό επίχρισμα ερυθράς ιλύος σε βάθος νερού 265 m, στο υφαλόριο. Στην λεκάνη του κεντρικού Κορινθιακού Κόλπου η ερυθρά ιλύς σχημάτισε επάλληλα επιφανειακά και υπο-επιφανειακά στρώματα τα οποία εναλλάσσονται με φυσικά ιζήματα. Τη δεκαετία του 1990 η μέση ετήσια παραγωγή ερυθράς ιλύος ήταν 640,000 τόνοι. Μέχρι το 1994 οι αποθέσεις της ερυθράς ιλύος στον πυθμένα της υφαλοκρηπίδας εκτείνονται σε 36.5 km2, και ανέρχονται σε όγκο που εκτιμάται στους 40.8 εκατ. τόνους. Η οπτική διασκόπηση έδειξε ότι ένα λεπτό επιφανειακό στρώμα ερυθράς ιλύος να καλύπτει τον φυσικό πυθμένα της υφαλοκρηπίδας μέχρι το υφαλόριο, σε βάθος νερού 265 m. Στην κεντρική λεκάνη του Κορινθιακού κόλπου οι αποθέσεις της ερυθράς ιλύος συνολικά καλύπτουν 288 km2 του πυθμένα. O όγκος των αποθέσεων της ερυθράς ιλύος στη λεκάνη εκτιμήθηκε στους 1.96 εκατ. τόνους. Ο συνολικός όγκος της ερυθράς ιλύος που έχει απορριφθεί από το 1970-1994 στο βόρειο περιθώριο του Κορινθιακού Κόλπου αγγίζει τους 43 εκατ. τόνους. Από αυτό το υλικό μόλις το 4.5 % μεταφέρεται στην κεντρική λεκάνη του Κορινθιακού Κόλπου, ενώ το 95.5 % παραμένει στην υφαλοκρηπίδα του Κόλπου της Αντίκυρας. Δύο μηχανισμοί κυρίως ευθύνονται για τη διασπορά της ερυθράς ιλύος από την κύρια απόθεση στην υφαλοκρηπίδα. Ο υψηλός ρυθμός ιζηματογένεσης στους λοβούς εξαιτίας της μεγάλης ποσότητας υλικού που απορρίπτεται από τους αγωγούς, προκαλεί αύξηση στους πόρους των ιζημάτων και οδηγεί σε αστοχίες στα πρανή των λοβών. Ο έτερος μηχανισμός, οποίος είναι και ο πιο σημαντικός, αφορά στην έντονη σεισμικότητα της περιοχής έρευνας. Ένας αριθμός σεισμών που έχουν εκδηλωθεί στην ευρύτερη περιοχή του Κόλπου της Αντίκυρας, για την χρονική περίοδο που μελετήθηκε η ερυθρά ιλύς (1994-2007), είχαν μέγεθος (Ms>5) ικανό να προκαλέσει υποθαλάσσιες βαρυτικές μετακινήσεις μαζών. Επιπλέον το σεισμικό τους επίκεντρο βρισκόταν σε απόσταση μικρότερη των 60 km από την περιοχή της απόθεσης της ερυθράς ιλύος. Οι σεισμοί αυτοί δυνητικά έπληξαν τους λοβούς της ερυθράς ιλύος και πυροδότησαν υποθαλάσσιες κατολισθήσεις. Οι κατολισθήσεις από τα πρανή των λοβών μετασχηματίζονται σε ροή μάζας που διασπείρουν την ερυθρά ιλύ στον πυθμένα της υφαλοκρηπίδας, μέχρι το υφαλόριο. Στο υφαλόριο η αύξηση της κλίσης του πρανούς μετασχηματίζει τις ροές μάζας σε τουρβιδιτικά ρεύματα που μεταφέρουν την ερυθρά ιλύ στην κεντρική λεκάνη του Κορινθιακού Κόλπου. Στα ανώτερα 20 cm των επιφανειακών ιζημάτων της κεντρικής λεκάνης του Κορινθιακού Κόλπου, αναγνωρίστηκαν οκτώ (8) ιζηματολογικές ενότητες οι οποίες αποτελούν αποθέσεις λεπτόκοκκων τουρβιδιτών. Οι ενότητες σχηματίστηκαν από ισάριθμα τουρβιδιτικά ρεύματα που διέσχισαν την κατωφέρεια και μετάφεραν ερυθρά ιλύ, φυσικά ιζήματα ή και τα δύο. Διαπιστώθηκε μάλιστα ότι τα τουρβιδικά ρεύματα που σχημάτισαν τις επιφανειακές αποθέσεις της λεκάνης, διέσχισαν διαφορετικές χαραδρώσεις κάθε φορά, αλλά περισσότερες από μία χαράδρωση ενεργοποιήθηκαν σε κάθε τουρβιδιτικό γεγονός. Ο ρυθμός ιζηματογένεσης για τα ανώτερα 20 cm των ιζημάτων της κεντρικής λεκάνης υπολογίστηκε στην παρούσα εργασία και εκτιμάται από 0.8 έως 3.3 mm/yr. Είναι σημαντικά υψηλότερος από το ρυθμό ημιπελαγικής ιζηματογένεσης κατά τη διάρκεια του Ολοκαίνου στο Ιόνιο και το Αιγαίο αλλά κοντά στο μέσο ρυθμό ιζηματογένεσης που προέκυψε από τις πρόσφατες ενστρωμένες ακολουθίες τουρβιδιτών στη λεκάνη του Κορινθιακού Κόλπου, όπως αναφέρεται από προηγούμενες έρευνες. Η ερυθρά ιλύς εξαιτίας του μητρικού πετρώματος και της διεργασίας παραγωγής αποτελεί ένα ίζημα εμπλουτισμένο σε βαρέα μέταλλα καθώς χαρακτηρίζεται από υψηλές συγκεντρώσεις των βαρέων μετάλλων: Ag, Cd, Co, Cr, Cu, Hg, Ni, Pb, V, Al, Fe, Ti. Οι συγκεντρώσεις αυτές είναι πολύ υψηλότερες από τις αντίστοιχες του υποβάθρου (δείκτες εμπλουτισμού >>1). Παρατηρήθηκε ωστόσο αραίωση των συγκεντρώσεων των παραπάνω μετάλλων στις αποθέσεις της υφαλοκρηπίδας και της λεκάνης σε σχέση με την ερυθρά ιλύ στις επίγειες δεξαμενές στο εργοστάσιο επεξεργασίας (δείκτες αραίωσης <1). Πιθανώς η ανάμειξη της ερυθράς ιλύος με το θαλασσινό νερό κατά την απόρριψη από τους αγωγούς να προκαλεί μείωση των συγκεντρώσεων των μετάλλων. Οι βαρυτικές διεργασίες που λαμβάνουν χώρα στην περιοχή του Κορινθιακού Κόλπου και ευθύνονται για τη μεταφορά της ερυθράς ιλύος από τους λοβούς προς τα κατάντη επιδρούν στη σύσταση του μεταλλοφόρου ιζήματος. Κατά την μεταφορά προκαλείται ανάμειξη της ερυθράς ιλύος με το φυσικό ίζημα του πυθμένα. Αυτό έχει ως αποτέλεσμα να μειώνονται οι συγκεντρώσεις των βαρέων μετάλλων και η ερυθρά ιλύς να εμπλουτίζεται σε στοιχεία που αφθονούν στα φυσικά ιζήματα. / Corinth Gulf constitutes a natural laboratory for the study of sedimentary processes that control the sediment transport from the shelf to the deep basin floor. The gulf comprises an active continental margin which reaches a maximum depth of about 870 m and hosts a number of processes that alter the seafloor morphology and form the sedimentation regime. On the northern coast of the central Gulf of Corinth operates since 1970, a Submarine Tailings Disposal System. The tailings, also known as red mud, are the by-product of the bauxite processing for the aluminum production. Red mud is discharged on the shelf of the Antikyra Gulf. The present PhD research thesis studies the important environmental issue of the red mud tailings distribution and dispersion in the central Corinth Gulf. The study was based on a wide spectrum of primordial and original data collected by the Laboratory of Marine Geology & Physical Oceanography, in Department of Geology, University of Patras. Data collection was performed in four marine surveys from 1994 to 2007. The surveys comprised of marine geophysical exploration using Sub-bottom Profiler, Echo-sounder and Side Scan Sonar systems and visual inspection of the seafloor using an remotely operated vehicle (ROV). Furthermore, a dense grid of sediment samples using Day grab and also a gravity core, were collected. A series of laboratory analyses were performed for the physical, chemical and mineralogical characterization of the marine sample sediments. The geophysical dataset presented the detailed bathometry and morphology of the study area. The slope of the northern coast of the Corinth Gulf is incised by numerous of submarine canyons. Twenty eight canyons were identified and measured in terms of dimensions, dip of the walls and thickness of sediment cover. Seventeen of these are developed on the slope southwards from Antikyra Gulf. Red mud is being discharged on the shelf floor of Antikyra Gulf, at a water depth of 100-120 m through a submarine pipeline system. Red mud is a sludge which consists of fine-grained sediment particles (mud and sand) mixed with sea water. At the pipeline outfall site, on the shelf, red mud has formed a surface layer of significant thickness. By 1994 three submarine sediment lobes were formed. Lobe A, on the west, has maximum height of 14 m. Lobe B, in the center, rises 27 m above the seafloor. Lobe C, on the east has maximum elevation of 23 m. The three lobes merge into a common lobe-shape main red mud deposit. Red mud is dispersed from the main lobe-shape deposition. Visual inspection of the shelf seafloor has shown that the submarine pipelines are buried under a layer of red mud northwards from the lobes, in a water depth of about 53 m. Downhill from the lobes red mud disperse in a S-SW direction. Thus, a surface layer of red mud with minimum thickness of 1 m has formed and constitutes the wider red mud deposit, which encompass the main red mud deposit. Sediment samples presented that the shelf floor is covered by a thin surface layer of red mud with minimum thickness of few to 1 cm. Furthermore visual inspection showed a thin veneer of red mud covers the natural seafloor at the water depth of 265 m, at the shelf break. On the basin floor red mud has formed surface and sub-surface layers that intercalate with the natural sediments. During the '90s the mean annual red mud production was 640,000 tones. In 1994 the red mud deposits on the shelf floor cover 36.5 km2 and the total volume was estimated at 40.8 million tones. On the basin floor red mud layers cover 288 km2. The volume of the materials was estimated to be 1.96 million tones. The total volume of red mud that has been discharged from 1970 to 1994 is estimated to be 43 million tones. 4.5 % of the total volume of this material is being transported to the basin floor while the majority (95.5 %) lays on the shelf floor. The dispersion of red mud from the main deposition is attributed mainly to two processes. The high sedimentation rate at the lobes due to the ample supply of red mud from the pipelines, can cause excess sediment pore pressure and induce sediment failures from the lobes. The other process is associated with the high seismicity of the Corinth Gulf. During the period of the data collection (1994-2007) a number of earthquakes shocked the study area and had magnitudes (Ms>5) that were able to cause submarine sediment failures. Also the epicentral area laid in a distance of less than 60 km from the area of red mud deposits on the shelf. These earthquakes potentially stroke the lobe-shape deposit of the red mud and caused submarine sediment failures and landslides. The initial landslides at the lobes are transformed into mass flows that disperse the red mud on the shelf, floor as far as the shelf break. At the shelf break due to the dip increase, turbidity currents are triggered, cross the slope and carry the red mud at the central basin of the Corinth Gulf, where they finally deposit. In the upper 20 cm of the sedimentary cover of the basin floor were recognized eight discrete sedimentary units. These units bear characteristics of fine-grained turbidites and have been formed by different tourbidity currents that crossed the slope. The currents curried either red mud, or natural sediments or both. Each turbidity current that formed the sedimentary units on the basin floor, crossed more than one canyon on the slope each time. However each tourbiditic event crosses different canyons each time. The sedimentation rate for the upper sedimentary cover of the basin floor which consist of the red mud layers and the intercalating natural sediments, is estimated for the present study and ranges from 0.8 to 3.3 mm/y. This rate is higher than the hemipelagic sedimentation rate during the Holocene in Ionian and Aegean Sea. However is close to the mean sedimentation rate that has been estimated by the recent tourbiditic sequences in the central Corinth Gulf basin by previous works. Red mud due to the parental material and the production process is highly enriched in heavy metals such as Ag, Cd, Co, Cr, Cu, Hg, Ni, Pb, V, Al, Fe, Ti. The concentrations of these metals are extremely higher than the background values. However red mud deposits on the shelf and the basin floor are depleted in the heavy metal concentration comparing to the red mud in a onshore pool, prior to the submarine discharge. Mixing of red mud with seawater during the discharge from the pipelines decreases the levels of heavy metals. Also a depletion in metal concentration is observed in the basin floor red mud deposits comparing to the main red mud deposition at the lobes and this may be attributed to the gravitational processes that come about and transport the red mud from the source (lobes) to the sink (basin floor). During the transport takes place mixing between the red mud and the natural sediments. On the basin floor the red mud has decreased concentrations of metals and shows elevated concentrations in elements that abound in natural sediments.
37

Análise da influência das propriedades físicas do solo na deflagração dos escorregamentos translacionais rasos na Serra do Mar (SP) / Analysis of the influence of soil physical properties in the initiation of shallow landslides in the Serra do Mar (SP)

Ferreira, Fabiana Souza 17 January 2013 (has links)
Os movimentos de massa fazem parte da dinâmica da paisagem e se destacam como um dos principais processos geomorfológicos responsáveis pela evolução do relevo. Estes são condicionados por uma relação complexa de fatores naturais: geomorfológicos, geológicos e geotécnicos e hidrológicos. Tais tipos de movimentos de massa ficaram registrados em 17 e 18 de março de 1967 nas encostas da escarpa da Serra do Mar no município de Caraguatatuba, quando ocorreram de modo generalizado, causando um grande impacto ambiental, culminando em 120 mortes e 400 casas destruídas, mais concentrados em uma área de aproximadamente 180km2 em torno do município. Sendo assim, o objetivo deste trabalho é investigar algumas propriedades físicas do solo a fim de analisar a influência destas na distribuição e na deflagração dos escorregamentos translacionais rasos. As amostras de solo foram coletadas em três pontos, em diferentes profundidades (lateral, superior e interior) de três cicatrizes de escorregamentos rasos de 1967. As seguintes propriedades foram analisadas: distribuição granulométrica, limites de Atterberg, porosidade, densidade, curvas de retenção de água e resistência ao cisalhamento. As amostras apresentaram valores altos para as frações de areia, cerca de 80%, com uma composição granulométrica variável, destacando a existência de areias siltosas e pouco argilosas e siltes pouco argilosos, com os horizontes de solos mais profundos formados predominantemente por materiais siltosos e/ou arenosos, enquanto os horizontes superficiais apresentaram-se mais argilosos. Ainda que com baixos índices de atividade e por muitas vezes inatividades, não apresentaram significativa variabilidade quanto aos índices físicos onde os corpos de prova não atingiram a saturação total, alcançando uma média percentual de 70% de umidade e valores para densidade e índices de vazios muito próximos, de 2,55 g/cm3 e 1,151 g/cm3, respectivamente quanto aos parâmetros de resistência. Os ângulos de atrito foram menores para os horizontes superficiais (29,1º e 25,8º) em detrimento das camadas subjacentes, 1,75m e 2,00m, (31,9º e 36,8º). É importante ressaltar que boa parte dos estudos já desenvolvidos sobre a temática Serra do Mar Paulista focam o mapeamento destes processos na paisagem e o papel dos parâmetros topográficos, sobretudo da declividade, na distribuição dos mesmos. Entretanto, são escassas as informações sobre a tipologia e as propriedades dos solos, em escala de detalhe que possam efetivamente influenciar a estabilidade das encostas da Serra do Mar. Espera-se, portanto, que este estudo possa subsidiar em melhor entendimento dos mecanismos de ruptura dos escorregamentos rasos neste compartimento geomorfológico. / Mass movements are part of the landscape dynamics and stand out as major geomorphological processes responsible for the evolution of relief. These are determined by a complex of natural factors: geomorphological, geological and geotechnical and hydrological. These types of mass movements were recorded on 17 and 18 March 1967 on the slopes of the escarpment of the Serra do Mar in the city of Caraguatatuba, when there were so widespread, causing a major environmental impact, resulting in 120 deaths and 400 homes destroyed more concentrated in an area of approximately 180km2 around the county. Therefore, the objective of this work is to investigate some physical properties of the soil in order to analyze their influence on the distribution and outbreak of shallow translational landsliding. Soil samples were collected at three points at different depths (side, top and interior) of three shallow landslide scars from 1967. The following properties were analyzed: size distribution, Atterberg limits, porosity, density, water retention curves and shear strength. The samples had high values for the sand fractions, about 80%, with a variable grain size composition, highlighting the existence of silty sands and silts and clay little bit clay, with deeper soil horizons formed predominantly silty materials and / or sandy, while the surface horizons were more clay. Even with low levels of activity and often outages, showed no significant variation between the physical indexes where the samples have not reached full saturation, reaching an average percentage of 70% moisture content and density values for indices and very empty next, at 2.55 g/cm3 and 1.151 g/cm3, respectively for the parameters of resistance. The friction angles were smaller in surface horizons (29.1 º and 25.8 º) over the underlying layers, 1.75 m and 2.00 m (31.9 º and 36.8 º). Importantly, many of the studies already undertaken on the subject Serra do Mar Paulista focus on the mapping of these processes in the landscape and the role of topographic parameters, especially the slope in their distribution. However, there is little information about the types and properties of soils in detail scale that can effectively influence the stability of the slopes of the Serra do Mar. It is hoped, therefore, that this study may support better understanding of failure mechanisms of shallow landslides in geomorphological compartment.
38

Niveles de peligro de inestabilidad de las laderas de un sector del flanco norandino venezolano: Monte Carmelo, estado de Trujillo / Niveles de peligro de inestabilidad de las laderas de un sector del flanco norandino venezolano: Monte Carmelo, estado de Trujillo

Montiel A., Katty, Seco H., Ricardo 10 April 2018 (has links)
A zonation of slope instability hazard levels of the Mount Carmelo region was carried out based on an analysis of the geographical conditions using the Van Westen (2003) heuristic method and GIS. Three levels of instability hazard were established: low hazard areas (no actual harmful phenomena is recorded, although it might occur over the next years), moderate hazard (medium probability that harmful processes might appear over next years) and high hazard (high probability of harmful processes over the next years.) Zonation maps showing hazard areas will be very useful for physical planning and population protection, taking into· consideration   that  these  maps  may  reduce  economic  losses  and  human  casualties due to the above mentioned natural hazards. / Con la intención de establecer una zonificación de los niveles de peligro de inestabilidad  de laderas  de la región  de Monte  Carmelo,  se efectuó  un  análisis de las condiciones geográficas mediante la aplicación del método heurístico de Van Westen (2003) y de un SIG. Los resultados  obtenidos arrojaron tres niveles de peligro  de inestabilidad: peligro  bajo (no se presentan fenómenos dañinos, aunque se podrían presentar en los próximos años), peligro  moderado (moderada probabilidad de que aparezcan  fenómenos  dañinos  que  ocasionen  algún  tipo  de impacto  negativo  en los próximos años) y peligro alto (probabilidad alta de ocurrencia de un fenómeno dañino  para  la población  en  los  próximos  años). Los  mapas  de  zonificación  de áreas de peligro serán de gran utilidad para la planificación de los territorios y para la defensa civil, al contribuir a la reducción  de pérdidas  materiales y humanas que puedan  producirse  ante la ocurrencia  de estos  fenómenos.
39

Análise da influência das propriedades físicas do solo na deflagração dos escorregamentos translacionais rasos na Serra do Mar (SP) / Analysis of the influence of soil physical properties in the initiation of shallow landslides in the Serra do Mar (SP)

Fabiana Souza Ferreira 17 January 2013 (has links)
Os movimentos de massa fazem parte da dinâmica da paisagem e se destacam como um dos principais processos geomorfológicos responsáveis pela evolução do relevo. Estes são condicionados por uma relação complexa de fatores naturais: geomorfológicos, geológicos e geotécnicos e hidrológicos. Tais tipos de movimentos de massa ficaram registrados em 17 e 18 de março de 1967 nas encostas da escarpa da Serra do Mar no município de Caraguatatuba, quando ocorreram de modo generalizado, causando um grande impacto ambiental, culminando em 120 mortes e 400 casas destruídas, mais concentrados em uma área de aproximadamente 180km2 em torno do município. Sendo assim, o objetivo deste trabalho é investigar algumas propriedades físicas do solo a fim de analisar a influência destas na distribuição e na deflagração dos escorregamentos translacionais rasos. As amostras de solo foram coletadas em três pontos, em diferentes profundidades (lateral, superior e interior) de três cicatrizes de escorregamentos rasos de 1967. As seguintes propriedades foram analisadas: distribuição granulométrica, limites de Atterberg, porosidade, densidade, curvas de retenção de água e resistência ao cisalhamento. As amostras apresentaram valores altos para as frações de areia, cerca de 80%, com uma composição granulométrica variável, destacando a existência de areias siltosas e pouco argilosas e siltes pouco argilosos, com os horizontes de solos mais profundos formados predominantemente por materiais siltosos e/ou arenosos, enquanto os horizontes superficiais apresentaram-se mais argilosos. Ainda que com baixos índices de atividade e por muitas vezes inatividades, não apresentaram significativa variabilidade quanto aos índices físicos onde os corpos de prova não atingiram a saturação total, alcançando uma média percentual de 70% de umidade e valores para densidade e índices de vazios muito próximos, de 2,55 g/cm3 e 1,151 g/cm3, respectivamente quanto aos parâmetros de resistência. Os ângulos de atrito foram menores para os horizontes superficiais (29,1º e 25,8º) em detrimento das camadas subjacentes, 1,75m e 2,00m, (31,9º e 36,8º). É importante ressaltar que boa parte dos estudos já desenvolvidos sobre a temática Serra do Mar Paulista focam o mapeamento destes processos na paisagem e o papel dos parâmetros topográficos, sobretudo da declividade, na distribuição dos mesmos. Entretanto, são escassas as informações sobre a tipologia e as propriedades dos solos, em escala de detalhe que possam efetivamente influenciar a estabilidade das encostas da Serra do Mar. Espera-se, portanto, que este estudo possa subsidiar em melhor entendimento dos mecanismos de ruptura dos escorregamentos rasos neste compartimento geomorfológico. / Mass movements are part of the landscape dynamics and stand out as major geomorphological processes responsible for the evolution of relief. These are determined by a complex of natural factors: geomorphological, geological and geotechnical and hydrological. These types of mass movements were recorded on 17 and 18 March 1967 on the slopes of the escarpment of the Serra do Mar in the city of Caraguatatuba, when there were so widespread, causing a major environmental impact, resulting in 120 deaths and 400 homes destroyed more concentrated in an area of approximately 180km2 around the county. Therefore, the objective of this work is to investigate some physical properties of the soil in order to analyze their influence on the distribution and outbreak of shallow translational landsliding. Soil samples were collected at three points at different depths (side, top and interior) of three shallow landslide scars from 1967. The following properties were analyzed: size distribution, Atterberg limits, porosity, density, water retention curves and shear strength. The samples had high values for the sand fractions, about 80%, with a variable grain size composition, highlighting the existence of silty sands and silts and clay little bit clay, with deeper soil horizons formed predominantly silty materials and / or sandy, while the surface horizons were more clay. Even with low levels of activity and often outages, showed no significant variation between the physical indexes where the samples have not reached full saturation, reaching an average percentage of 70% moisture content and density values for indices and very empty next, at 2.55 g/cm3 and 1.151 g/cm3, respectively for the parameters of resistance. The friction angles were smaller in surface horizons (29.1 º and 25.8 º) over the underlying layers, 1.75 m and 2.00 m (31.9 º and 36.8 º). Importantly, many of the studies already undertaken on the subject Serra do Mar Paulista focus on the mapping of these processes in the landscape and the role of topographic parameters, especially the slope in their distribution. However, there is little information about the types and properties of soils in detail scale that can effectively influence the stability of the slopes of the Serra do Mar. It is hoped, therefore, that this study may support better understanding of failure mechanisms of shallow landslides in geomorphological compartment.
40

Interações sobre a pluviosidade em encostas de clima tropical úmido e os movimentos de massa: o caso de sub-bacias do Alto Rio São João - RJ / Interactions on rainfall in areas of moist tropical slopes and mass movements: the case of sub basins of the Upper St. John River - RJ

Sandro Castanho Parracho 30 August 2012 (has links)
Cada vez são mais comuns problemas relacionados a movimentos de massa nas encostas de clima tropical no Estado do Rio de Janeiro, especialmente na Serra do Mar, provocados por acumulados pluviométricos intensos. A ocupação humana desordenada de áreas sensíveis a tais processos geomorfológicos, bem como as condicionantes geológicas, geomorfológicas, pedológicas e de uso e cobertura do solo são apontadas como fatores cruciais na explicação desses processos. O maior conhecimento da dinâmica pluviométrica bem como suas interações com tais aspectos físicos ligados ao relevo parece ser a chave dessa maior compreensão desses fenômenos. Assim foram realizadas pesquisas relacionadas aos volumes e intensidades das chuvas na região do Alto Curso do Rio São João, bem como uma análise dos movimentos de massa identificados através de imagens de satélite e in loco, como forma de fornecer subsídios à melhor gestão do espaço dessas regiões montanhosa estão vulneráveis a movimentos de massa. A correlação entre os acumulados e a intensidade pluviométrica com fenômenos climáticos de escala global, como El Niño e La Niña também foi contemplada nessa pesquisa, mostrando uma relação mais alta com relação à intensidade da chuva mensal para anos de El Niño e para anos de La Niña uma reduzida ocorrência dessas intensidades pluviométricas. Os estudos revelaram que os tipos de solos e sua cobertura e uso têm uma grande influência na deflagração de movimentos de massa. Foram observados um número reduzido de movimentos de massa em áreas naturais e uma maior proporção desses movimentos em áreas utilizadas para a atividade da pecuária na região. Grande parte dos movimentos de massa ocorreram em áreas de Cambissolos (áreas mais elevadas) e Latossolos (áreas de encostas em menores altitudes). Ambos os solos são mais espessos do que os encontrados em áreas mais declivosas, apresentando maior acúmulo de materiais a serem mobilizados durante grandes acumulados pluviométricos, gerando movimentos de massa. A análise mostrou também que áreas mais chuvosas e com maior ocorrência de acumulados pluviométricos extremos, acima de 100 mm/dia e acima de 30mm/mês concentraram um número maior de movimentos de massa, como a região mais próxima da estação de Quartéis (porção leste). Por outro lado áreas bastante elevadas, com altas declividades, porém com predomínio de Mata Atlântica e áreas com solos menos espessos, como os Neossolos Litólicos, se mostraram com um número reduzido desses processos. Enfim esse estudo mostrou a necessidade de se gerir melhor os espaços dessas áreas sensíveis sob o ponto de vista geomorfológico, até por que são áreas na periferia de regiões densamente habitadas e cujas demandas tendem a se tornar cada vez mais marcantes, o que pode gerar problemas locais, atingindo sua população e economia, com sérias conseqüências para o ambiente. / Are increasingly common problems related to mass movements on the slopes of tropical climate in the State of Rio de Janeiro, especially in the Serra do Mar, caused by intense rainfall accumulated. The disorganized human occupation of sensitive areas such geomorphological processes and the geological conditions, geomorphology, soil and use and land cover are cited as crucial factors in explaining these processes. The understanding of rainfall dynamics as well as their interactions with such physical aspects related to the relief seems to be the key to this greater understanding of these phenomena. So were performed research related to volume and intensity of rainfall in the Upper St. John River Course, as well as an analysis of mass movements identified through satellite imagery and on-site as a way to provide subsidies to better management of these space mountainous regions as vulnerable to mass movements. The correlation between rainfall intensity and accumulated with global-scale climatic phenomena like El Niño and La Niña was also considered in this study, showing a higher ratio with respect to the intensity of monthly rainfall for El Niño years and La Niña years a reduced occurrence of rainfall intensities. Studies have shown that the types of soils and their cover and land use have a great influence on outbreaks of mass movements. We observed a small number of mass movements in natural areas and a higher proportion of these movements in areas used for livestock activity in the region. Most mass movements occurred in areas of Cambisols (higher areas) and Oxisols (slopes in areas of lower altitudes). Both soils are thicker than those found in hilly areas, with higher accumulation of materials to be deployed during large accumulated rainfall, generating mass movements. The analysis also showed that areas with increased wet and accumulated occurrence of precipitation extreme excess of 100 mm/day and above 30mm/month concentrated a larger number of mass movements, as the region closest to the station Quartéis (East portion).On the other hand very high areas with steep slopes, but with a predominance of Atlantic Forest and areas with thinner soils, such as Entisols, were with a small number of these processes. Finally this study showed the need to better manage these areas, sensitive areas under the geomorphological point of view, even for areas that are on the outskirts of densely populated and whose demands tend to become increasingly salient, which can cause problems locations, reaching its population and economy, with serious consequences for the environment

Page generated in 0.3343 seconds