• 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.
41

Suscetibilidade a movimentos de massa na microbacia do Ribeirão Máximo, município de Luis Alves / Mass Movements susceptibility in the micro basin of ribeirão Máximo, Luis Alves Municipality, SC

Santos, Elisa Volker dos 02 July 2012 (has links)
Made available in DSpace on 2016-12-08T16:55:41Z (GMT). No. of bitstreams: 1 elisa.pdf: 11036235 bytes, checksum: 94721d4ef4f11108675ebd447aa2c20e (MD5) Previous issue date: 2012-07-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This dissertation aims to analyze the mass movements susceptibility in the micro basin of ribeirão Máximo, which is located at the southwest of Luis Alves municipality, in the low Itajaí Valley, northeastern Santa Catarina State, with coordinates 26°43 23.22 and 26°47 17.83 S and 48°53 16.02 and 48°57 27.96 W. The mass movements are phenomena of the earth natural morphodynamics and work in sculpture and evolution of the relief, through the detachment and transport of soil and/or rock material downward slope, by gravity action. However, the great focus on these processes takes place due to the increase of occurrences involving occupied areas with big social and environmental losses. The environmental disaster occurred in 2008 in Santa Catarina State, which affected mainly Itajaí Valley, has joined forces of the scientific community (GTC, FAPESC) in the search for understanding these phenomena that have caused so much damage and losses. In this context, Luis Alves municipality was one of the most affected, motivating the development of this research. Only in the micro basin of ribeirão Máximo were mapped 18 mass movements scars resulting from this period of intense precipitation. The work method proposed is based on the systemic analysis, adopting the watershed as the unit of analysis, with the use of theoretical work, field and lab methods, through the study and integration of local environmental specificities, climatology, geology, geomorphology, pedology, land use, in the quest for the conditioners involved in the mass movements occurrences in the micro basin of ribeirão Máximo. The environmental characteristics of the micro basin of ribeirão Máximo, humid subtropical climate with high precipitation indexes, high grade metamorphic lithologies of the Granulitic Complex of Santa Catarina State with structural lineaments and marked discontinuity plans, rugged and sloping relief with steep hillsides and deep valleys, and thick soils, added to inadequate antropic actions in hillsides, as cuts for construction of houses and roads, predispose the development of erosion and destabilizing processes. The results point the structural lineaments, the geomorphologic features, the slope and the land use as the main conditioners involved in the mass movements occurrences in the micro basin of ribeirão Máximo. The integration of these conditioners in SIG environment enabled the generation of the mass movements susceptibility map of the micro basin of ribeirão Máximo, with the hierarchization of the area in five susceptibility classes: very low, low, medium, high and very high. The detailed study of one of the 18 mass movements scars mapped in the micro basin of ribeirão Máximo allowed a wider understanding of the actuation of the conditioners involved in the occurrences of mass movements, mainly the soil behavior, confirming the low resistance of C horizon and indicating that the ruptures occur mainly in this horizon
42

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
43

Genesis, conservation and deformation of ice-rich mountain permafrost:

Kenner, Robert 30 May 2018 (has links) (PDF)
This thesis analyses ice-rich mountain permafrost with regard to its genesis, distribution, deformation and interaction with other environmental factors. The processes influencing ground ice formation in ice-rich and ice-poor mountain permafrost are highlighted. Factors influencing the presence of ice-rich permafrost are identified and their individual or combined effect on frozen ground is determined. Based on these findings, a new permafrost distribution map of Switzerland was created, which specifies permafrost temperature and ice contents and considers rock glacier creep paths. The deformation of rock glaciers is investigated with newly developed monitoring systems and concepts. This enables a better understanding of the processes leading to rock glacier acceleration at different time scales.
44

Genesis, conservation and deformation of ice-rich mountain permafrost:: Driving factors, mapping and geodetic monitoring

Kenner, Robert 29 January 2018 (has links)
This thesis analyses ice-rich mountain permafrost with regard to its genesis, distribution, deformation and interaction with other environmental factors. The processes influencing ground ice formation in ice-rich and ice-poor mountain permafrost are highlighted. Factors influencing the presence of ice-rich permafrost are identified and their individual or combined effect on frozen ground is determined. Based on these findings, a new permafrost distribution map of Switzerland was created, which specifies permafrost temperature and ice contents and considers rock glacier creep paths. The deformation of rock glaciers is investigated with newly developed monitoring systems and concepts. This enables a better understanding of the processes leading to rock glacier acceleration at different time scales.

Page generated in 0.087 seconds