Orientador: Fabiano Tomazini da Conceição / Resumo: O processo de denudação continental é controlado por fatores exógenos como intemperismo químico e erosão dos solos. Nesse processo, os sistemas fluviais desempenham um papel fundamental ao transportar os materiais sólidos e dissolvidos de seu local origem até atingir os oceanos. Visando investigar o balanço de denudação no Planalto Alcalino de Poços de Caldas – MG, adotou-se o método de balanço de massa geoquímico aplicado em escala de bacia hidrográfica, cuja análise quantitativa foi baseada nos fluxos de entrada e saída de elementos/compostos químicos em duas pequenas bacias hidrográficas situadas na borda noroeste do planalto. A média da descarga fluvial de sólidos dissolvidos foi estimada em 32,5 t km-2 ano-1 sendo que cerca de 40 % desse fluxo foi atribuído à deposição atmosférica (14,0 t km-2 ano-1) enquanto o restante foi associado ao intemperismo químico das rochas (18,5 t km2 ano-1), enquanto a descarga sólida, estimada em 5,4 t km-2 ano-1, demostra um sistema fluvial de baixo fluxo de sedimento. A taxa de intemperismo químico de fonólitos, tinguaítos e nefelina sienito de Poços de Caldas (2,1 m Ma) foi inferior à taxa de remoção dos solos do planalto (4,0 m Ma), revelando uma tendência de exumação das rochas do maciço a uma velocidade de 1,9 m Ma. A taxa de denudação do Planalto de Poços de Caldas foi reduzida com o passar do tempo geológico e sob o clima atual o relevo de Poços de Caldas tende a se manter na paisagem com pouca alteração em sua forma em um lento pro... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The continental denudation process is controlled by exogenous factors such as chemical weathering and soil erosion. In this process, river systems play a key role in transporting solid and dissolved materials from their source site to the oceans. In order to investigate the denudation balance in the Poços de Caldas Alkaline Plateau - MG, the geochemical mass balance method applied in a watershed scale was adopted, whose quantitative analysis was based on the input and output flows of chemical elements / compounds in two small watersheds situated on the northwest edge of the plateau. The average fluvial discharge of dissolved solids was estimated at 32.5 t km-2 year-1 and about 40% of this flow was attributed to atmospheric deposition (14.0 t km-2 year-1) while the remainder was associated with the chemical weathering of the rocks (18.5 t km-2 year-1), while the solid discharge estimated at 5.4 t km-2 year-1 demonstrates a low sediment flow river system. The chemical weathering rate of phonolites, tinguaites and nepheline syenite from Poços de Caldas (2.1 m Ma) was lower than the removal rate from the plateau soils (4.0 m Ma), revealing a tendency for rock mass exhumation at a speed of 1.9 m Ma. The denudation rate of the Poços de Caldas Plateau has been reduced over time and under current weather the relief of Poços de Caldas tends to remain in the landscape with little change in its form in a slow process of exhumation of the rocks. / Doutor

The present study comprised an intensive investigation of the two newly proposed parameterisation forms for the wind input source term S[subscript]in (Donelan et a1., 2006) and the wave dissipation source term S[subscript]ds (Young and Babanin, 2006) proposed on the basis of the recent experimental findings at Lake George, New South Wales, Australia in 1997-2000. The main objective of this study was to obtain advanced spectral forms for the wind input source function S[subscript]in and wave spectral dissipation source function S[subscript]ds, which satisfy important physical constraints. A new approach was developed to achieve the objectives of this study, within the strong physical framework. This approach resulted in a new balance scheme between the energy source terms in the wave model, mentioned before as the split balance scheme (Badulin, 2006). The wave-induced stress was defined as the main physical constraint for a new wave model including recently suggested source functions for the wind input and wave dissipation source terms. Within this approach, a new methodology was developed for correction of the wind input source function S[subscript]in. Another important physical constraint was the consistency between the wave dissipation and the wind energy input to the waves. The new parameter, the dissipation rate, R, was introduced in this study, as the ratio of the wave dissipation energy to the wind input energy. The parameterisation form of the dissipation rate is presented as a function of the inverse wave age U ₁₀ / c[subscript]p Some aspects of wave spectral modelling regarding the shape of the wave spectrum and spectral saturation were revised. The two-phase behaviour of the spectral dissipation function was investigated in terms of the functional dependency of the coefficients a for the inherent wave breaking term and b for the forced dissipation term. The present study found that the both coefficients have functional dependence on the inverse wave age U ₁₀ / c[subscript]p and the spectral frequency. Based on the experimental data by Young and Babanin (2006), a new directional spreading function of bimodal shape was developed for the wave dissipation source term. The performance of the new spectral functions of the wind input S[subscript]in(f) and the wave dissipation S[subscript]ds(f) source terms was assessed using a new third-generation two-dimensional research wave model WAVETIME-I. The model incorporating the corrected source functions was able to reproduce the existing experimental data. / Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2009

The present study comprised an intensive investigation of the two newly proposed parameterisation forms for the wind input source term S[subscript]in (Donelan et a1., 2006) and the wave dissipation source term S[subscript]ds (Young and Babanin, 2006) proposed on the basis of the recent experimental findings at Lake George, New South Wales, Australia in 1997-2000. The main objective of this study was to obtain advanced spectral forms for the wind input source function S[subscript]in and wave spectral dissipation source function S[subscript]ds, which satisfy important physical constraints. A new approach was developed to achieve the objectives of this study, within the strong physical framework. This approach resulted in a new balance scheme between the energy source terms in the wave model, mentioned before as the split balance scheme (Badulin, 2006). The wave-induced stress was defined as the main physical constraint for a new wave model including recently suggested source functions for the wind input and wave dissipation source terms. Within this approach, a new methodology was developed for correction of the wind input source function S[subscript]in. Another important physical constraint was the consistency between the wave dissipation and the wind energy input to the waves. The new parameter, the dissipation rate, R, was introduced in this study, as the ratio of the wave dissipation energy to the wind input energy. The parameterisation form of the dissipation rate is presented as a function of the inverse wave age U ₁₀ / c[subscript]p Some aspects of wave spectral modelling regarding the shape of the wave spectrum and spectral saturation were revised. The two-phase behaviour of the spectral dissipation function was investigated in terms of the functional dependency of the coefficients a for the inherent wave breaking term and b for the forced dissipation term. The present study found that the both coefficients have functional dependence on the inverse wave age U ₁₀ / c[subscript]p and the spectral frequency. Based on the experimental data by Young and Babanin (2006), a new directional spreading function of bimodal shape was developed for the wave dissipation source term. The performance of the new spectral functions of the wind input S[subscript]in(f) and the wave dissipation S[subscript]ds(f) source terms was assessed using a new third-generation two-dimensional research wave model WAVETIME-I. The model incorporating the corrected source functions was able to reproduce the existing experimental data. / Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2009

The present study comprised an intensive investigation of the two newly proposed parameterisation forms for the wind input source term S[subscript]in (Donelan et a1., 2006) and the wave dissipation source term S[subscript]ds (Young and Babanin, 2006) proposed on the basis of the recent experimental findings at Lake George, New South Wales, Australia in 1997-2000. The main objective of this study was to obtain advanced spectral forms for the wind input source function S[subscript]in and wave spectral dissipation source function S[subscript]ds, which satisfy important physical constraints. A new approach was developed to achieve the objectives of this study, within the strong physical framework. This approach resulted in a new balance scheme between the energy source terms in the wave model, mentioned before as the split balance scheme (Badulin, 2006). The wave-induced stress was defined as the main physical constraint for a new wave model including recently suggested source functions for the wind input and wave dissipation source terms. Within this approach, a new methodology was developed for correction of the wind input source function S[subscript]in. Another important physical constraint was the consistency between the wave dissipation and the wind energy input to the waves. The new parameter, the dissipation rate, R, was introduced in this study, as the ratio of the wave dissipation energy to the wind input energy. The parameterisation form of the dissipation rate is presented as a function of the inverse wave age U ₁₀ / c[subscript]p Some aspects of wave spectral modelling regarding the shape of the wave spectrum and spectral saturation were revised. The two-phase behaviour of the spectral dissipation function was investigated in terms of the functional dependency of the coefficients a for the inherent wave breaking term and b for the forced dissipation term. The present study found that the both coefficients have functional dependence on the inverse wave age U ₁₀ / c[subscript]p and the spectral frequency. Based on the experimental data by Young and Babanin (2006), a new directional spreading function of bimodal shape was developed for the wave dissipation source term. The performance of the new spectral functions of the wind input S[subscript]in(f) and the wave dissipation S[subscript]ds(f) source terms was assessed using a new third-generation two-dimensional research wave model WAVETIME-I. The model incorporating the corrected source functions was able to reproduce the existing experimental data. / Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2009