Debris flows occur frequently in remote areas of Great Smoky Mountains National Park, Tennessee. Rainfall gauges are not adequate for modeling infiltration required for triggering debris flows. Weather radar, providing frequently updated, continuous coverage, is a valuable tool for estimating rainfall intensity, duration, runoff, and infiltration. Daily rainfall from a sole gauge was compared with hourly rainfall from the Digital Precipitation Array weather radar product to model infiltration on August 5, 2012, the day before a debris flow was known to have occurred in the 91-km2West Prong Little Pigeon River watershed. Additionally, both gauge and radar data were used for rainfall-runoff-infiltration modeling for a 42-day period in July and August 2012. Runoff and infiltration were simulated using the conventional semi-distributed hydrological model HEC-HMS. A local bias correction of radar rainfall at the gauge location improved correlation between the radar rainfall and the gauge data. Peak daily rainfall for the August 5 storm was 93 mm (gauge) and 98 mm (radar), whereas average daily rainfall for the 42-day period was 10 mm and 7.75 mm, respectively. Over the study period, simulated daily infiltration declined from 28 mm to 0.5 mm for the gauge and from 15 mm to 0.14 mm for radar, indicating essentially saturated conditions on the day of the debris flow.

No description available.

Climate change is leading to in an increase in frequency and severity of wildfires, which in turn can result in the formation of runoff-initiated post-wildfire debris flows. This type of debris flows is, like most debris flows, triggered by heavy precipitation events. Debris flows have the potential to cause much damage, and therefore it is important to analyse when and where the risk of these flows exists. This study aims to identify shared characteristics of basins that experienced post-wildfire debris flows in order to improve future risk analyses regarding such flows. These characteristics were studied through the analysis of 42 basins in 10 burned areas across western North America, which experienced a total of 67 post-wildfire debris flows between 2000 and 2018. Literature research and existing databases revealed the bedrock, soil texture and the timing of the flows compared to the wildfires. Spatial analysis using ArcMap allowed for the analysis of the burn severity of the basins, the hypsometry of the basins, and the mean slope of the basins. Analysis of these characteristics revealed the importance of the hypsometric integral, the soil texture, and the mean slope angle of the basins. In general, the hypsometric integral tends to fall between 0.50 and 0.60 and only soils with a coarse texture were identified for the basins. The mean slope angle of the basins is commonly between 25-30o, with a wider range of slopes being able to generate debris flows shortly after the fire. If multiple basins in a small area are burned, those with steeper slope angles have a higher potential to generate debris flows, while basins with steeper slopes do not have a higher risk on large regional scales. In order to generate post-wildfire debris flows the basin also needs to be burned at a large extent at low to medium severity, resulting in an extensive and strong water-repellent layer required to generate the runoff that is needed to generate a debris flow. Seasonal wetting during winters and drying of the soil during summers can reduce or enhance runoff respectively as well. As a result, post-wildfire debris flows occur mostly during the late summer months shortly after a wildfire when precipitation is increasing through summer storms, or a year later when the soil is dried and primed during the summer followed by such a summer storm. Fires during winter and thus outside the traditional wildfire season can lead to post-wildfire debris flows during winter as well due to the strength of the fresh water-repellent layer. Climate change which will lead to more fires during late autumn and winter months can thereby result in post-wildfire debris flows during winter, rather than only during the summer months following wildfires in the traditional fire season. / Jordskred uppstår när en sammanhängande jordmassa kommer i snabb rörelse. Det är en typ av naturolyckor som kan skada både infrastruktur och människor. Sannolikheten att ett jordskred inträffar ökar efter skogsbränder. Samtidigt kan klimatförändringar leda till en ökning av skogsbränder vilket i sin tur kan leda till en ökad risk för jordskred i framtiden. Syftet med det här projektet är att bidra till bedömningen av risken av jordskred till följd av skogsbänder i västra Nordamerika och att identifiera andra områden som också har en stor risk att drabbs av skred efter skogsbränder genom att identifiera riskfaktorer. Under projektets gång skapades en databas med områden där jordskred inträffade efter skogsbränder i västra Nordamerika. Den vetenskapliga litteraturen visade några egenskaper av skred och områdena, t.ex. när branden och skredet hände, vilken berggrund finns i området och texturen av jordarten i området. Dessutom användandes GIS (Geographical Information System) med satellitbilder och DEM (Digital Elevation models), som visade information om brandskador samt de geomorfologiska karaktärerna av områden. Resultaten visade att formationen av jordskred kräver omfattande låga till måttliga brandskador som resulterar i ett starkt vattenavvisande jordlager. Detta jordlager minskar infiltrationskapaciteten av jorden och resulterar i mer ytavrinning vilket orsakar skred till följd av brand. Även en grov textur av jordlagret är viktig eftersom den också bidrar till ett starkt vattenavvisande jordlager. Dessutom kan askpartiklar bli fångade in i stora porer i jord med en grov textur vilket minskar infiltrationskapaciteten och ökar ytavrinningen. Det finns alltså två krav för att ett jordskred ska inträffa efter en skogsbrand: i) omfattande låga-måttliga brandskador, och ii) en grov textur av jorden. Vidare finns det några ytterligare egenskaper som ökar risken för skred efter skogsbränder om de två kraven är uppfyllda. Den hypsometriska integralen (ett sätt att uttrycka hypsometrin av en dal) ligger oftast mellan 0.50-0.60 vilket är normal för en geomorfologiskt sett mogna område. Dessutom hade de flesta områdena i projektet en medellutning mellan 25o och 30o. Dock fanns det även tillfällen där värdena låg utanför dessa intervaller. Därför kan dessa värden i sig inte användas som riskfaktorer, utan borde de även kombineras med de övriga egenskaperna som beskrivs i den här undersökningen. Det är också relevant att veta när jordskred inträffar till följd av skogsbränder. Resultaten visade att skred kan hända strax efter skogsbränder i slutet av sommaren när det finns kraftigt regn. Det är då som det vattenavvisande jordlagret är som starkast. Det vattenavvisande lagret minskar i styrkan under året, men det är också möjligt att det inträffar ett jordskred under sommaren året efter en skogsbrand. Då är jorden torr i slutet av sommaren när kraftigt regn inträffar efter torra månader. Torr jorden bidrar även till en minskad infiltrationskapacitet. Regn i vinter gör jorden blöt vilket ökar infiltrationskapaciteten av jorden. Dessutom sker det även skogsbränder utanför den traditionella skogsbrandsäsongen nuförtiden, t.ex. tidigt i vintern. I så fall kan jordskred också inträffa under samma vinter strax efter skogsbranden, därför att det vattenavvisande jordlagret som skapas i branden fortfarande är starkt då. Som nämnts tidigare finns det en riskprofil som kan användas för att identifiera områden som har en hög risk för jordskred efter skogsbränder, men möjligheten att ett jordskred inträffar under vintern istället för (slutet av) sommaren bör även iakttas. Risken växer nämligen i samband med klimatförändringar som leder till mer skogsbränder; inte bara under sommaren, utan även under vintern.

Esta pesquisa teve como hipótese que as corridas de detritos são os principais processos responsáveis pela evolução do relevo da Serra do Mar (SP), esperando-se, portanto, uma relação direta entre as taxas de denudação a longo-termo mais elevadas e a maior magnitude das corridas de detritos, sendo esta fortemente controlada pela morfometria das bacias de drenagem. Acredita-se que as características morfométricas das bacias, por serem determinantes na dinâmica hidrológica das bacias de drenagem, são fundamentais para a compreensão da geração e da propagação de corridas de detritos em ambiente tropical úmido. Desta forma, o objetivo principal desta pesquisa foi verificar as relações existentes entre a magnitude das corridas de detritos, a morfometria das bacias e as taxas de denudação a longo-termo em relevo escarpado de margem passiva em ambiente tropical úmido, como a Serra do Mar. Para tanto, foram definidos os seguintes objetivos específicos: (i) avaliar o potencial de geração de corridas de detritos das bacias de drenagem; (ii) avaliar a relação entre a morfometria das bacias e a magnitude das corridas de detritos; (iii) discutir a evolução a longo-termo do relevo a partir das taxas de denudação em escala de bacia de drenagem e; (iv) avaliar a importância das corridas de detritos como os principais processos exógenos para a evolução do relevo em margens passivas de ambiente tropical úmido. Os procedimentos adotados para desenvolvimento da pesquisa foram (i) seleção das bacias de drenagens; (ii) amostragem de sedimento aluvial; (iii) mapeamento dos depósitos de corridas de detritos; (iv) aplicação dos índices morfométricos; (v) aplicação dos Índices Adimensionais para determinação do potencial de geração de corridas de detritos; (vi) preparação das amostras e análise da concentração de 10Be e; (vii) análise integrada dos resultados obtidos. As bacias possuem características morfométricas que lhes confere alta capacidade erosiva, conforme o elevado Índice de Rugosidade e Relação de Relevo. A partir da aplicação dos índices Adimensionais, as bacias classificadas com maior potencial de geração de corridas foram a Rio Claro 1 e a Massaguaçu. A identificação dos depósitos de corridas em superfície e a dimensão dos blocos subsidiaram a classificação de cinco bacias com maior magnitude e cinco com menor magnitude. As taxas de denudação médias a longo-termo variaram entre 10,9 m/My e 35,2 m/My, com média de 25 m/My. Observou-se que as variações litológicas e a rede de lineamentos estruturais pôde explicar melhor a distribuição das taxas, em detrimento das características morfométricas das bacias de drenagem. Acredita-se que as taxas de denudação elevadas para algumas bacias com menor magnitude indicaram que estes processos seriam os processos responsáveis pelo maior trabalho geomorfológico e, consequentemente, pela evolução a longo-termo da Serra do Mar (SP). / This research has the hypothesis that debris flows are the major processes related to landforms evolution of the Serra do Mar (SP), and we expected therefore a direct relationship between long-term denudation rates and higher magnitude debris flows events, which is strongly controlled by drainage basin morphometry. We believe that morphometric characteristics, fundamental to drainage basins hydrological dynamics, are determinant to debris flows initiation and propagation in humid tropical environments. Thus this research aims to verify the relationships between debris flows magnitude, basin morphometry and long-term denudation rates in escarped reliefs such as Serra do Mar. Therefore, specific goals are: (i) evaluate the potential to debris flows generation; (ii) evaluate the relationship between drainage basin morphometry and debris flows magnitude; (iii) discuss long-term landforms evolution from denudation rates at drainage basin scale and; (iv) evaluate the importance of debris flows like the main exogenous processes to landforms evolution in passive margins in humid tropical environment. The procedures adopted to the research development were: (i) selection of drainage basins; (Ii) alluvial sediment sampling; (Iii) mapping debris flows deposits; (Iv) application of morphometric parameters; (V) application of Dimensionless Indices to measure the potential to debris flow generation; (Vi) sample preparation and analysis of 10Be concentration; (Vii) integrated analysis of the results. The basins have morphometric characteristics which gives them high erosive power, as the high Ruggedness Index and Relief Ratio. From the Dimensionless Indices application, the basins classified with higher potential to debris flows generation were Rio Claro 1 and Massaguaçu. The identification of superficial debris flows deposits and boulders size subsidized the classification of five basins with higher magnitude and five with lower magnitude. Long-term denudation rates ranged between 10.9 m/My and 35.2 m/My, averaging 25 m/My. We observed that lithological variations, fractures and folds could explain better rates distribution, instead of morphometrics characteristics of drainage basins. We believe that high long-term denudation rates for some basins with lower magnitude indicates that such processes would be the main processes for the geomorphological work and consequently for the long-term evolution of the Serra do Mar (SP).

As corridas de detritos são processos caracterizados por escoamentos rápidos associados a precipitações intensas e/ou acumuladas. A ocorrência destes processos está associada a diversas variáveis do meio físico e quando associadas a eventos extremos de precipitação podem gerar grande volume de sedimentos como aqueles observados em 1967 no município de Caraguatatuba (SP). Neste contexto, o objetivo desta pesquisa foi avaliar o potencial de geração de corridas de detritos a partir do emprego de parâmetros morfométricos para as bacias hidrográficas dos rios Santo Antônio, Guaxinduba e Mococa. Metodologicamente, o trabalho dividiu-se, em um primeiro momento, na identificação dos escorregamentos e das zonas de arraste e deposição das corridas de detritos. Posteriormente, foram extraídos os parâmetros e os índices morfométricos das bacias (área, amplitude, comprimento do canal, ângulo da encosta, índice de circularidade, densidade de drenagem e declividade média do canal), e analisados de forma qualitativa e quantitativa. A partir do reconhecimento dos processos foram selecionadas as sub-bacias para a aplicação de dois modelos empíricos considerando os valores de concentração de sólidos e de precipitação. Assim, por meio dos cenários propostos de 60 mm/h e 100 mm/h e concentração de sólidos de 50% foram obtidos os valores de vazão e de volume de sedimentos das corridas de detritos para cada sub-bacia selecionada. Os resultados obtidos na análise qualitativa mostraram similaridades entre as bacias dos rios Santo Antônio e Mococa, fato este não observado para a bacia do Guaxinduba. No entanto, a bacia do Guaxinduba apresentou maior potencial para a geração de corridas de detritos. Em 40 sub-bacias, observou-se que houve diferença de aproximadamente 60% da vazão e volume em relação aos cenários de 60 mm/h e 100 mm/h. Além disso, observou-se nas formulações empregadas que a inserção de variáveis geram valores distintos de vazão de pico e volume de sedimentos. Identificou-se que a bacia do Guaxinduba apresentou maior potência, porém com volumes inferiores aos observados nas bacias do Santo Antônio e Mococa. Acredita-se que a combinação destes métodos pode auxiliar na identificação de áreas suscetíveis à ocorrência das corridas de detritos em regiões serranas, como o Litoral Norte de São Paulo. / Debris flow processes are characterized by rapid runoff associated with heavy and/or accumulated rainfall. The occurrence of these processes is associated with several variables of the physical environment and when associated with extreme precipitation events can generate large amounts of sediment as those observed in 1967 in the city of Caraguatatuba (SP). In this context, the objective of this research was to evaluate the potential of generating debris flow from the use of morphometric parameters for the river basins of the Santo Antonio, Guaxinduba and Mococa. Methodologically, the work was divided, at first, the identification of landslides and areas of deposition of debris flow. Subsequently, the parameters and morphometric indices of the basins were extracted (area, basin relief, channel length, slope angle, circularity ratio, drainage density and average channel slope), and analyzed qualitatively and quantitatively. Based the recognition of the processes the sub-basins to the application of two empirical models considering the solid concentration values and precipitation were selected. Thus by the proposed scenarios of 60 mm / h and 100 mm/h solids concentration of 50% were obtained the values of peak discharges and magnitude of debris flow for each selected sub-basin. The results of the qualitative analysis showed similitarities between the rivers basins of the Santo Antônio and Mococa, which is not observed for the basin Guaxinduba. However, the basin Guaxinduba showed greater potential for the generation of debris flow. In sub-basin 40, it was observed that there was a difference of approximately 60% of peak discharges and magnitude in relation to the scenarios of 60 mm/h and 100 mm/h. Furthermore, it was observed that the formulations employed in the insertion variables generate different peak and magnitude values of sediment. It was identified that the Guaxinduba basin showed a higher power, but with magnitude lower than those observed in the basins of Santo Antônio and Mococa. It is believed that the combination of these methods can help identify areas susceptible to the occurrence of debris flow in mountainous regions such as the North Coast of São Paulo.

Esta pesquisa teve como hipótese que as corridas de detritos são os principais processos responsáveis pela evolução do relevo da Serra do Mar (SP), esperando-se, portanto, uma relação direta entre as taxas de denudação a longo-termo mais elevadas e a maior magnitude das corridas de detritos, sendo esta fortemente controlada pela morfometria das bacias de drenagem. Acredita-se que as características morfométricas das bacias, por serem determinantes na dinâmica hidrológica das bacias de drenagem, são fundamentais para a compreensão da geração e da propagação de corridas de detritos em ambiente tropical úmido. Desta forma, o objetivo principal desta pesquisa foi verificar as relações existentes entre a magnitude das corridas de detritos, a morfometria das bacias e as taxas de denudação a longo-termo em relevo escarpado de margem passiva em ambiente tropical úmido, como a Serra do Mar. Para tanto, foram definidos os seguintes objetivos específicos: (i) avaliar o potencial de geração de corridas de detritos das bacias de drenagem; (ii) avaliar a relação entre a morfometria das bacias e a magnitude das corridas de detritos; (iii) discutir a evolução a longo-termo do relevo a partir das taxas de denudação em escala de bacia de drenagem e; (iv) avaliar a importância das corridas de detritos como os principais processos exógenos para a evolução do relevo em margens passivas de ambiente tropical úmido. Os procedimentos adotados para desenvolvimento da pesquisa foram (i) seleção das bacias de drenagens; (ii) amostragem de sedimento aluvial; (iii) mapeamento dos depósitos de corridas de detritos; (iv) aplicação dos índices morfométricos; (v) aplicação dos Índices Adimensionais para determinação do potencial de geração de corridas de detritos; (vi) preparação das amostras e análise da concentração de 10Be e; (vii) análise integrada dos resultados obtidos. As bacias possuem características morfométricas que lhes confere alta capacidade erosiva, conforme o elevado Índice de Rugosidade e Relação de Relevo. A partir da aplicação dos índices Adimensionais, as bacias classificadas com maior potencial de geração de corridas foram a Rio Claro 1 e a Massaguaçu. A identificação dos depósitos de corridas em superfície e a dimensão dos blocos subsidiaram a classificação de cinco bacias com maior magnitude e cinco com menor magnitude. As taxas de denudação médias a longo-termo variaram entre 10,9 m/My e 35,2 m/My, com média de 25 m/My. Observou-se que as variações litológicas e a rede de lineamentos estruturais pôde explicar melhor a distribuição das taxas, em detrimento das características morfométricas das bacias de drenagem. Acredita-se que as taxas de denudação elevadas para algumas bacias com menor magnitude indicaram que estes processos seriam os processos responsáveis pelo maior trabalho geomorfológico e, consequentemente, pela evolução a longo-termo da Serra do Mar (SP). / This research has the hypothesis that debris flows are the major processes related to landforms evolution of the Serra do Mar (SP), and we expected therefore a direct relationship between long-term denudation rates and higher magnitude debris flows events, which is strongly controlled by drainage basin morphometry. We believe that morphometric characteristics, fundamental to drainage basins hydrological dynamics, are determinant to debris flows initiation and propagation in humid tropical environments. Thus this research aims to verify the relationships between debris flows magnitude, basin morphometry and long-term denudation rates in escarped reliefs such as Serra do Mar. Therefore, specific goals are: (i) evaluate the potential to debris flows generation; (ii) evaluate the relationship between drainage basin morphometry and debris flows magnitude; (iii) discuss long-term landforms evolution from denudation rates at drainage basin scale and; (iv) evaluate the importance of debris flows like the main exogenous processes to landforms evolution in passive margins in humid tropical environment. The procedures adopted to the research development were: (i) selection of drainage basins; (Ii) alluvial sediment sampling; (Iii) mapping debris flows deposits; (Iv) application of morphometric parameters; (V) application of Dimensionless Indices to measure the potential to debris flow generation; (Vi) sample preparation and analysis of 10Be concentration; (Vii) integrated analysis of the results. The basins have morphometric characteristics which gives them high erosive power, as the high Ruggedness Index and Relief Ratio. From the Dimensionless Indices application, the basins classified with higher potential to debris flows generation were Rio Claro 1 and Massaguaçu. The identification of superficial debris flows deposits and boulders size subsidized the classification of five basins with higher magnitude and five with lower magnitude. Long-term denudation rates ranged between 10.9 m/My and 35.2 m/My, averaging 25 m/My. We observed that lithological variations, fractures and folds could explain better rates distribution, instead of morphometrics characteristics of drainage basins. We believe that high long-term denudation rates for some basins with lower magnitude indicates that such processes would be the main processes for the geomorphological work and consequently for the long-term evolution of the Serra do Mar (SP).

Bryant and Eastern Canyon systems are located on the northwest Gulf of Mexico, and they are characterized by a very complex sedimentological history related to glacioeustatic cycles, river discharges, and interactions of depositional and halokinetic processes. Both canyon systems were active during the low sea-level stand of Oxygen Isotope Stage 6, and provided the pathways for the transport of enormous amounts of sediments on the continental slope and abyssal plain of the northwest Gulf of Mexico. Right after their abandonment, at the beginning of Stage 5, salt diapirs encroached into the canyons, and resulted in their transformation into a network of intraslope basins. The transformation of the canyons resulted in the generation of massive sediment failures. The mid-shelf (Stages 4 and 3) to shelf edge (Stage 2) lowering of the sea-level during the last glacial episode resulted in: 1) extensive river-sourced deposits on the outer shelf and/or upper continental slope that contributed in a seaward mobilization of the underlying salt masses, and 2) the generation of numerous gravity flows and turbidity currents on the outer shelf/upper continental slope. The seaward mobilization of the salt masses resulted in the oversteepening of the flanks of the basins, and consequently in the generation of numerous and massive sediment failures. The turbidity currents were confined on the intraslope basins of the upper continental slope, depositing their coarsest material. However, their most diluted upper and end members were able to continue their downslope propagation depositing characteristic fine-grained turbidites. The frequency of the turbidity currents was highly increased during the last glacial maximum (Stage 2), and three short melt-water pulses centered at 30.5, 36, and 52 ky B.P. The last deglaciation event is characterized by the development of a major melt water event that resulted in the deposition of distinct organic rich sediments, similar to the sapropels of the Eastern Mediterranean. At about 11 ky B.P. the melt water discharges of the North America switched from Mississippi River to St Lawrence Seaway, causing the domination of hemipelagic sedimentation on the continental slope of the northwest Gulf of Mexico.

Submitted by Claudia Vanessa dos Santos Corrêa (claudiageobrax@yahoo.com.br) on 2018-06-06T02:32:25Z No. of bitstreams: 1 VERSAO FINAL COMPLETA.pdf: 29221186 bytes, checksum: e01b175cba96e8af54b4c7995ec5262a (MD5) / Approved for entry into archive by Ana Paula Santulo Custódio de Medeiros null (asantulo@rc.unesp.br) on 2018-06-06T12:02:22Z (GMT) No. of bitstreams: 1 correa_cvs_dr_rcla.pdf: 29196738 bytes, checksum: 8314696946ba060a96b1d3d2775068a3 (MD5) / Made available in DSpace on 2018-06-06T12:02:23Z (GMT). No. of bitstreams: 1 correa_cvs_dr_rcla.pdf: 29196738 bytes, checksum: 8314696946ba060a96b1d3d2775068a3 (MD5) Previous issue date: 2018-03-12 / Outra / As corridas de detritos são movimentos de massa que se desenvolvem ao longo de redes de drenagem e envolvem fluidos densos, compostos por materiais de diferentes granulometrias e composições, bem como quantidades variáveis de água, identificados como processos naturais constituintes da dinâmica e da modelagem da paisagem. Caracterizam-se pelo extenso raio de alcance, altas velocidades, altas vazões de pico e elevada capacidade de erosão e força de impacto. As áreas mais susceptíveis a ocorrência desses processos no Brasil estão situadas no sopé da Serra do Mar, da Serra da Mantiqueira e da Serra Geral, e no litoral norte do Estado de São Paulo foi registrado um grande evento de escorregamentos e corridas de detritos generalizados em 1967 que afetou a região de Caraguatatuba e São Sebastião, onde se encontra uma malha dutoviária associada a Unidades de Tratamento da Petrobras, outros empreendimentos, estruturas e uma grande área urbana em crescimento. O objetivo geral desta pesquisa é propor uma metodologia para avaliação da potencialidade de bacias hidrográficas à ocorrência de corridas de detritos, através do emprego da compartimentação fisiográfica, de estudos de retroanálise e da simulação numérica do terreno com o software RAMMS. A compartimentação fisiográfica revelou que as unidades que possuem contato direto com planícies são aquelas que possuem maior potencialidade a corridas de detritos. Na retro-análise, foi estabelecido o Fator de Desproporcionalidade, que possibilitou a análise de incoerências de incidência de cicatrizes de escorregamento em bacias hidrográficas, unidades geológicas e classes de declividade. As bacias Camburu, Pau D’Alho, Canivetal e Santo Antônio foram consideradas como as mais afetadas por escorregamentos e corridas de detritos, sendo que a classe de declividade de 350 a 500 é a mais atingida nesses locais e não houve uma unidade geológica preferencial durante a mobilização desses processos. A simulação numérica revelou que as corridas de detritos da Serra do Mar apresentam um fluxo com caráter reológico predominantemente granular e as zonas de deposição das corridas dão-se preferencialmente em regiões de baixa declividade. O emprego desta metodologia pode auxiliar na identificação de locais com potencialidade a corrida de detritos, especialmente na Serra do Mar, e contribuir com a gestão do meio físico. / The debris flows are mass movements that develop along drainage networks and involve generally dense fluids, compose of materials of different granulometries and compositions, as well as variable amounts of water, identified as natural processes that constitute the dynamics and the modeling the landscape. They are characterized by the long range, high speeds, high peak flows, high erosion capacity and impact force. The areas most susceptible to the occurrence of these processes in Brazil are in the foothills of the Serra do Mar, Serra da Mantiqueira and Serra Geral, and on the north coast of São Paulo State there was a great event of landslides and debris flows in 1967 which affected the region of Caraguatatuba and São Sebastião, where there is a pipeline network associated with Petrobras Treatment Units, other enterprises, structures and a large urban area in growth. The general aim of this research is to propose a methodology to evaluate the potential of watersheds to the occurrence of debris flows, using physiographic compartmentalization, retro-analysis studies and numerical simulation of the terrain with Ramms software. The physiographic compartmentalization revealed that the units that have direct contact with lowlands are those that have greater susceptibility to debris flows. In the retro-analysis, the Disproportionality Factor was established, which made it possible to analyze inconsistencies in the incidence of landslide scars in watersheds, geological units and declivity classes. The Camburu, Pau D’Alho, Canivetal and Santo Antônio watersheds were the most affected by landslides and debris flows, and the slope class of 350 to 500 is the most affected in these areas and there was no preferential geological unit during the mobilization of these processes. The numerical simulation revealed that the Serra do Mar debris flows have a predominantly granular rheological flow and the deposition zones of the flows are given in regions of low slope. Thus, the use of this methodology can help in the identification of areas with potential for the debris flows, especially in Serra do Mar, and contribute to the management of the physical environment.

Les roches argileuses, très sensibles à la dégradation par les agents atmosphériques, se caractérisent par des mécanismes de glissement complexes, impliquant des glissements/éboulements de versants et la reprise ultérieure des matériaux argileux glissés et déstructurés par des laves torrentielles. Ce double mécanisme, très fréquent dans les Alpes, pose un problème aux responsables de l'aménagement du territoire, en raison de la soudaineté et de la dangerosité des éboulements et des laves torrentielles en cas de forte pluviométrie. Récemment, les méthodes de traitement du bruit sismique acquis en continu sur des mouvements de terrain rapides (éboulements et glissements coulées dans les sols argileux) ont montré qu'il était possible de mesurer des variations de paramètres sismiques (fréquences de résonance, vitesse de propagation des ondes S) de la zone instable. Dans deux cas d'étude (éboulement et coulée), le suivi temporel de ces paramètres à partir du bruit sismique a montré une variation significative avant le déclenchement d'un évènement gravitaire, pouvant être interprétée comme un signal précurseur. Le projet présenté vise à mettre au point une méthodologie de suivi temporel des mouvements complexes affectant les roches argileuses à partir de mesures de bruit sismique et d'acquisitions photogrammétriques. Des capteurs sismiques ont été implantés à la fois dans la zone de départ des éboulements et dans les ravines qui canalisent le matériau éboulé, afin d'étudier les variations de différents paramètres sismiques avant des instabilités de versant et le déclenchement de laves torrentielles. Ces mesures de bruit sismique ont été couplées à des campagnes d'acquisition photogrammétrique, ce qui a permis de déterminer les taux d'érosion des versants par éboulement et d'évaluer les volumes de matériaux déstabilisés susceptibles d'être affectés par des laves torrentielles. / Clay-rich rocks are very sensitive to weathering and are affected by complex sliding mechanisms, involving both slope sliding/falling and debris flows in a second stage. This double mechanism often occurs in the Alps and raise a problem for land managers, because of the suddenness of falls and flows. Recent studies have showed that continuous ambient vibration recordings could be used to infer seismic parameters (e.g. resonance frequency, shear wave velocity) that characterize the unstable mass. In both cases (falls and flows), the monitoring of these parameters evidences a significant variation before the triggering of gravitational movements, which has been interpreted as a precursory signal. We develop and test a monitoring methodology for such complex movements affecting clay-rich rocks, from ambient vibration measurements and photogrammetric acquisitions. We installed seismic sensors both in the scarp area and in the gullies, in which the material deposits, in order to study variations in seismic parameters before the triggering of movements. By combining these seismic measurements with regular photogrammetric acquisitions, we determine slope erosion rates and evaluate the material volumes likely to be affected by debris flows.

As corridas de detritos são processos caracterizados por escoamentos rápidos associados a precipitações intensas e/ou acumuladas. A ocorrência destes processos está associada a diversas variáveis do meio físico e quando associadas a eventos extremos de precipitação podem gerar grande volume de sedimentos como aqueles observados em 1967 no município de Caraguatatuba (SP). Neste contexto, o objetivo desta pesquisa foi avaliar o potencial de geração de corridas de detritos a partir do emprego de parâmetros morfométricos para as bacias hidrográficas dos rios Santo Antônio, Guaxinduba e Mococa. Metodologicamente, o trabalho dividiu-se, em um primeiro momento, na identificação dos escorregamentos e das zonas de arraste e deposição das corridas de detritos. Posteriormente, foram extraídos os parâmetros e os índices morfométricos das bacias (área, amplitude, comprimento do canal, ângulo da encosta, índice de circularidade, densidade de drenagem e declividade média do canal), e analisados de forma qualitativa e quantitativa. A partir do reconhecimento dos processos foram selecionadas as sub-bacias para a aplicação de dois modelos empíricos considerando os valores de concentração de sólidos e de precipitação. Assim, por meio dos cenários propostos de 60 mm/h e 100 mm/h e concentração de sólidos de 50% foram obtidos os valores de vazão e de volume de sedimentos das corridas de detritos para cada sub-bacia selecionada. Os resultados obtidos na análise qualitativa mostraram similaridades entre as bacias dos rios Santo Antônio e Mococa, fato este não observado para a bacia do Guaxinduba. No entanto, a bacia do Guaxinduba apresentou maior potencial para a geração de corridas de detritos. Em 40 sub-bacias, observou-se que houve diferença de aproximadamente 60% da vazão e volume em relação aos cenários de 60 mm/h e 100 mm/h. Além disso, observou-se nas formulações empregadas que a inserção de variáveis geram valores distintos de vazão de pico e volume de sedimentos. Identificou-se que a bacia do Guaxinduba apresentou maior potência, porém com volumes inferiores aos observados nas bacias do Santo Antônio e Mococa. Acredita-se que a combinação destes métodos pode auxiliar na identificação de áreas suscetíveis à ocorrência das corridas de detritos em regiões serranas, como o Litoral Norte de São Paulo. / Debris flow processes are characterized by rapid runoff associated with heavy and/or accumulated rainfall. The occurrence of these processes is associated with several variables of the physical environment and when associated with extreme precipitation events can generate large amounts of sediment as those observed in 1967 in the city of Caraguatatuba (SP). In this context, the objective of this research was to evaluate the potential of generating debris flow from the use of morphometric parameters for the river basins of the Santo Antonio, Guaxinduba and Mococa. Methodologically, the work was divided, at first, the identification of landslides and areas of deposition of debris flow. Subsequently, the parameters and morphometric indices of the basins were extracted (area, basin relief, channel length, slope angle, circularity ratio, drainage density and average channel slope), and analyzed qualitatively and quantitatively. Based the recognition of the processes the sub-basins to the application of two empirical models considering the solid concentration values and precipitation were selected. Thus by the proposed scenarios of 60 mm / h and 100 mm/h solids concentration of 50% were obtained the values of peak discharges and magnitude of debris flow for each selected sub-basin. The results of the qualitative analysis showed similitarities between the rivers basins of the Santo Antônio and Mococa, which is not observed for the basin Guaxinduba. However, the basin Guaxinduba showed greater potential for the generation of debris flow. In sub-basin 40, it was observed that there was a difference of approximately 60% of peak discharges and magnitude in relation to the scenarios of 60 mm/h and 100 mm/h. Furthermore, it was observed that the formulations employed in the insertion variables generate different peak and magnitude values of sediment. It was identified that the Guaxinduba basin showed a higher power, but with magnitude lower than those observed in the basins of Santo Antônio and Mococa. It is believed that the combination of these methods can help identify areas susceptible to the occurrence of debris flow in mountainous regions such as the North Coast of São Paulo.