This study extends the methodology for the delineation of capture zones to base flow contribution areas for stream reaches under the assumption of constant average annual base flow in the stream. The methodology is applied to the Alder Creek watershed in southwestern Ontario, using three different numerical models. The three numerical models chosen for this research were Visual Modflow, Watflow and HydroGeoSphere. Capture zones were delineated for three different stream segments with reverse particle tracking and reverse transport. The modelling results showed that capture zones delineated for streams are sensitive to the discretization scheme and the different processes considered (i.e. unsaturated zone, surface flow). It is impossible to predict the size, shape and direction of the capture zones delineated based on the model selected. Also, capture zones for different stream segments will reach steady-state at different times. In addition, capture zones are highly sensitive to differences in hydraulic conductivity due to calibration. It was found that finite element based integrated groundwater - surface water models such as HydroGeoSphere are advantageous for the delineation of capture zones for streams. Capture zones created for streams are subject to greater uncertainty than capture zones created for extraction wells. This is because the hydraulic gradients for natural features are very small compared to those for wells. Therefore, numerical and calibration errors can be the same order of magnitude as the gradients that are being modelled. Because of this greater uncertainty, it is recommended that particle tracking and reverse transport always be used together when delineating capture zones for stream reaches. It is uncertain which probability contour to choose when the capture zone is delineated by reverse transport alone. The reverse particle tracks help choose the appropriate probability contour to represent the stream capture zone.

This study extends the methodology for the delineation of capture zones to base flow contribution areas for stream reaches under the assumption of constant average annual base flow in the stream. The methodology is applied to the Alder Creek watershed in southwestern Ontario, using three different numerical models. The three numerical models chosen for this research were Visual Modflow, Watflow and HydroGeoSphere. Capture zones were delineated for three different stream segments with reverse particle tracking and reverse transport. The modelling results showed that capture zones delineated for streams are sensitive to the discretization scheme and the different processes considered (i.e. unsaturated zone, surface flow). It is impossible to predict the size, shape and direction of the capture zones delineated based on the model selected. Also, capture zones for different stream segments will reach steady-state at different times. In addition, capture zones are highly sensitive to differences in hydraulic conductivity due to calibration. It was found that finite element based integrated groundwater - surface water models such as HydroGeoSphere are advantageous for the delineation of capture zones for streams. Capture zones created for streams are subject to greater uncertainty than capture zones created for extraction wells. This is because the hydraulic gradients for natural features are very small compared to those for wells. Therefore, numerical and calibration errors can be the same order of magnitude as the gradients that are being modelled. Because of this greater uncertainty, it is recommended that particle tracking and reverse transport always be used together when delineating capture zones for stream reaches. It is uncertain which probability contour to choose when the capture zone is delineated by reverse transport alone. The reverse particle tracks help choose the appropriate probability contour to represent the stream capture zone.

The relatively rapid stream capture of the New River basin by the Roanoke River basin provides a unique example of topographic change within a tectonically inactive environment. A previous investigation of abandoned river deposits has shown the capture of ~225 km2 of New River basin area, which has caused approximately 250 m of incision by the Roanoke River (Prince et al., 2011). Difference in base level elevations between the lower Roanoke to the higher New River could be the source of potential energy driving rapid incision (Prince et al., 2011). Significant incongruities in base level elevations at the boundaries of an aquifer can steepen the gradient and shift the groundwater divide further toward the higher elevation boundary (Yechieli et al., 2009). If a steep groundwater gradient and expanded groundwater basin exists beneath the Roanoke River tributaries, this would suggest a groundwater control on incision and capture. In this investigation we incorporate average total head, measured from 18 domestic wells, and constant-head river boundary conditions into numerical models to calculate water levels and gradients between the rivers. We also utilized thermal patterns and particle tracking of spring locations to better understand flow paths in the region. Our results show the groundwater divide is shifted toward the higher elevation boundary, indicating that the groundwater basin is captured prior to surface capture. Flow pathways utilized by groundwater capture can be either diffuse or conduits, however further work should be done to better understand travel times and flow depths. / Master of Science

Stream capture is a major driver of the retreat of the Blue Ridge Escarpment, but timescales of capture are not well understood. This study examines stream sediment geochemistry to establish a set of sediment source fingerprints which can be used to identify and date the capture of the Tallulah River. Statistical analyses show significant differences in U, Th, and certain REE enrichment. These differences result from variations in bedrock along the lengths of each river and a shift in relative stream powers after capture to favor mobilization or deposition of heavy elements. The observed differences should be sufficient to identify where Tallulah sediment appears in floodplains of the capturing Tugaloo River, facilitating future dating of the capture event. Understanding the timing of river capture will provide insight into the ongoing reshaping and redistribution of river systems and interactions of geomorphic processes in the continuing evolution of the southern Appalachian Mountains.

The mechanism through which the Appalachian Mountains have maintained moderate relief some ~300 Myr after the cessation of mountain building has long puzzled geomorphologists. As recent studies have shown that Appalachian exhumation has occurred at slow rates consistent with isostatic rebound of thickened crust, the driving forces behind localized episodes of accelerated incision and the associated rugged topography have been difficult to explain given the absence of tectonic uplift. This study uses previously undocumented relict fluvial gravels and knickpoint location to confirm the role of drainage rearrangement in producing local base level drop and subsequent basin-scale transient incision in the southern Appalachians. This process is fundamentally driven by the high potential energy of streams flowing across the elevated, slowly eroding Blue Ridge Plateau relative to the present Atlantic and landward interior base levels. Gravel deposits confirm that repeated capture of landward-draining Plateau streams by Atlantic basin streams, whose immediate base level is 250-300 m lower, forces episodic rapid incision and overall erosional retreat of the Blue Ridge Escarpment along the Plateau margin. The distribution of knickpoints, bedrock gorges, and relict surfaces in the interior of the Plateau indicate that the New River, which drains to the continental interior, is actively incising the low-relief Plateau surface due to episodic drops in landward base level. The origin of landward base level perturbation is unclear, but it may be the result of glacially-driven shortening and steepening of the lower New River during the Pleistocene. Collectively, these data indicate that rapid base level drop through drainage reorganization can energize streams in otherwise stable landscapes and accelerate fluvial incision and relief production without uplift of the land surface. This process is likely quite significant in post-orogenic settings, where inherited drainage patterns may not reflect the most direct, and thus energetically appropriate, path to present base level. Passive margins may therefore never achieve a topographic steady-state, despite uniformly slow and constant uplift due to isostatic rebound. / Ph. D.

A pesquisa teve como objetivo compreender o papel dos rearranjos de drenagem à evolução do relevo e da drenagem na bacia hidrográfica do Rio Capivari, situada no reverso da Serra do Mar, em São Paulo-SP. Parte-se da hipótese de que esses fenômenos seriam responsáveis por inúmeras anomalias de drenagem observadas, como: inflexões em ângulos retos, padrões de drenagem anômalos, colos, rupturas em perfis longitudinais e subdimensionamento de cursos dágua em relação aos vales. Especial ênfase foi dada à inflexão do alto Rio Capivari, localizada na confluência com o Ribeirão Embura, possível remanescente de uma captura fluvial, o qual melhor preserva as evidências de um rearranjo em toda a bacia. Os principais fatores dos rearranjos de drenagem na área foram: o forte gradiente hipsométrico proporcionado pela Serra do Mar, a densa trama de foliações e fraturas presentes no embasamento geológico, movimentações tectônicas recentes e as oscilações paleoclimáticas do Quaternário tardio. Sob influência dessas forças, alguns tributários da drenagem litorânea teriam se aproveitado de sua vantagem erosiva frente aos rios de planalto, produzido uma marcha de erosão regressiva em direção ao interior, com interferências nos canais situados em níveis sucessivamente mais elevados. Com base nas propostas metodológicas de Small (1972), Bishop (1995), Zaprowski et al. (2002) e Oliveira (2003), buscou-se a identificação de elementos morfológicos e sedimentológicos sugestivos desses processos, por meio de: análise de Modelos Digitais do Terreno (MDE) por métodos geomorfométricos; observação de fotografias aéreas; trabalhos de campo para descrição e coleta de materiais sedimentológicos; análise granulométrica, morfoscópica e mineralógica de sedimentos fluviais; e datação de sedimentos fluviais por Luminescência Óptica Estimulada para se estimar a idade da captura do alto curso do Rio Capivari. Os dados apresentados corroboram a hipótese de que o alto curso desse rio sofreu uma captura há cerca de 8.000 anos, no máximo, e que diversos outros casos de rearranjos de drenagem, entre eles reversões de grandes sistemas fluviais, seriam responsáveis pelas anomalias de drenagem observadas no interior da bacia estudada. / The aim of this research was to understand the role of drainage rearrangements on the evolution of relief and drainage in the Capivari River basin, located on the reverse of Serra do Mar range, in the state of São Paulo, Brazil. It is assumed that these phenomena would be responsible for numerous drainage anomalies observed, such as: river inflections at right angles, anomalous drainage patterns, cols, knickpoints and river underfitting, considered as indicative for drainage rearrangements. Special emphasis will be given to the inflection of the Capivari River at the confluence with the Ribeirao Embura, a possible remnant of a stream capture, which best preserves the evidence of a rearrangement throughout the basin. The main factors of the drainage rearrangements in the area would be: the strong hypsometric gradient provided by Serra do Mar range, the set of foliations and fractures densely present in the geological basement, recent tectonic movements and climatic oscillations of the Quaternary. Under the influence of these forcings, some tributaries of the coastal drainage would have taken erosive advantage over the plateau upside rivers, producing a regressive erosion march towards the interior of the continent, leading to interferences in the river systems situated at successively higher levels. Based on the methodological proposals of Small (1972), Bishop (1995), Zaprowski et al. (2002) and Oliveira (2003), we seek the identification of morphological and sedimentological elements that are suggestive of these processes, by means of: Digital Elevation Models (DEM) analysis by geomorphometric methods; observation of aerial photographs; fieldwork for description and collection of sedimentological materials; granulometric, morphoscopic and mineralogical analysis of fluvial sediments; and dating of fluvial sediments by Optically Stimulated Luminescence to estimate the age of capture of the upper reaches of the Capivari River. The presented data corroborate the hypothesis that the high course of the Capivari river was captured at least 8,000 years ago and that several other cases of drainage rearrangements, including reversals of large river systems, would be responsible for the observed drainage anomalies.

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / O Rio do Paraíba do Sul está encaixado sobre rochas neoproterozóicas do Brasiliano possuindo uma direção principal ENE-WSW que companha o strike das camadas geológicas. Próximo à cidade de Sapucaia-RJ o vale deste rio apresenta um estrangulamento denominado aqui de Estreito de Sapucaia. Através da análise de mapa hipsométrico, de perfis topográficos e do perfil longitudinal do Rio Paraíba do Sul, foi constatado que a feição morfológica do Estreito de Sapucaia é um divisor de drenagem regional de direção NNW-SSE e um nível de base regional que dita o trabalho erosivo realizado pelo Paraíba do Sul e de parte de seus afluentes na área estudada. O mapa hidrológico apresenta canais com mudanças abruptas de direção, indicativos de capturas de drenagem, sendo que muitas vezes essa mesma direção continua nos canais de bacias hidrográficas contíguas formando lineamentos de vales separados por um divisor. Estas capturas de drenagem acontecem em afluentes do Rio Paraíba do Sul que possuem direções contrárias a ele, assim como o Rio Calçado que flui por cerca de 20 km na direção oposta até mudar de direção próximo a sua foz no próprio Rio Paraíba do Sul. Estes canais de direção contrária ao rio principal sugerem a existência de uma antiga direção principal para oeste, que foi modificada por capturas de drenagem originadas a partir do rebaixamento de um paleo-divisor que existia no local onde hoje é o Estreito de Sapucaia e que dividia o Paraíba do Sul em dois segmentos de direções distintas, ENE e WSW. Acredita-se que este fato ocorreu durante a reativação tectônica rúptil na transição Mesozóico/Cenozóico quando foram geradas estruturas que se sobrepuseram às antigas estruturas até então existentes, reorganizando, assim, a distribuição dos fluxos hidrológicos. A inversão da direção do fluxo hidrológico para ENE aumentou a área de influência do Paraíba do Sul incrementando a quantidade de sedimentos disponíveis para o preenchimento da Bacia de Campos. Desta forma, acredita-se que esta captura de drenagem teve como data o Meso-Eoceno que marca o momento em que a Bacia de Campos deixa de estar faminta para receber um grande aporte sedimentar / The Paraíba do Sul River flows over.Neoproterozoic rocks of Brasiliano, with preference direction ENE-WSW the same of the strike of geologic layers. In the Sapucaia-RJ city the valley of Paraíba do Sul river is strangle. This feature is called here Sapucaia Strait. Throught the analysis of the Hipsometric Map, the topographies profiles and the longitudinal profile of the Paraíba do Sul River, was verified that this morphological feature is a regional drainage divided with NNW-SSE direction and a regional Knickpoint thats commands the erosion realized by the Paraíba do Sul River and his tributaries. The Hidrologic Map shows streams with abrupt changing of direction. Sometimes this direction continuous in streams of hidrological basins contiguous, originating relief lineaments, indicating stream capture. These stream captures happen in the tributaries of the Paraíba do Sul River with different direction of him, like the Calçado River that flows 20 km in the opposite direction up to his outfall in the property Paraíba do Sul River. These channels with opposite direction of the leading river suggest the existence of archaic mainly direction to West, thats being modified by the streams captures originated by the degrade of one paleo-divider that exists in the place where today is the Sapucaia Strait and divided the Paraíba do Sul River in two segments, ENE e WSW. This research, believes that this fact occurred at the Mesozoic/Cenozoic tectonic when was created structures that overlapped the olds structures that exists, reorganizing the distribution of the hydrologic flows. The inversion of the hydrologic flows increased the area of the Paraíba do Sul River enlarging the quantity of sediments that fills the Campos Basin. We expect, that this stream capture occurred in Meso-Eoceno when the Campos Basin stop to be starving and passes to receive a lot of sediments

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / O Rio do Paraíba do Sul está encaixado sobre rochas neoproterozóicas do Brasiliano possuindo uma direção principal ENE-WSW que companha o strike das camadas geológicas. Próximo à cidade de Sapucaia-RJ o vale deste rio apresenta um estrangulamento denominado aqui de Estreito de Sapucaia. Através da análise de mapa hipsométrico, de perfis topográficos e do perfil longitudinal do Rio Paraíba do Sul, foi constatado que a feição morfológica do Estreito de Sapucaia é um divisor de drenagem regional de direção NNW-SSE e um nível de base regional que dita o trabalho erosivo realizado pelo Paraíba do Sul e de parte de seus afluentes na área estudada. O mapa hidrológico apresenta canais com mudanças abruptas de direção, indicativos de capturas de drenagem, sendo que muitas vezes essa mesma direção continua nos canais de bacias hidrográficas contíguas formando lineamentos de vales separados por um divisor. Estas capturas de drenagem acontecem em afluentes do Rio Paraíba do Sul que possuem direções contrárias a ele, assim como o Rio Calçado que flui por cerca de 20 km na direção oposta até mudar de direção próximo a sua foz no próprio Rio Paraíba do Sul. Estes canais de direção contrária ao rio principal sugerem a existência de uma antiga direção principal para oeste, que foi modificada por capturas de drenagem originadas a partir do rebaixamento de um paleo-divisor que existia no local onde hoje é o Estreito de Sapucaia e que dividia o Paraíba do Sul em dois segmentos de direções distintas, ENE e WSW. Acredita-se que este fato ocorreu durante a reativação tectônica rúptil na transição Mesozóico/Cenozóico quando foram geradas estruturas que se sobrepuseram às antigas estruturas até então existentes, reorganizando, assim, a distribuição dos fluxos hidrológicos. A inversão da direção do fluxo hidrológico para ENE aumentou a área de influência do Paraíba do Sul incrementando a quantidade de sedimentos disponíveis para o preenchimento da Bacia de Campos. Desta forma, acredita-se que esta captura de drenagem teve como data o Meso-Eoceno que marca o momento em que a Bacia de Campos deixa de estar faminta para receber um grande aporte sedimentar / The Paraíba do Sul River flows over.Neoproterozoic rocks of Brasiliano, with preference direction ENE-WSW the same of the strike of geologic layers. In the Sapucaia-RJ city the valley of Paraíba do Sul river is strangle. This feature is called here Sapucaia Strait. Throught the analysis of the Hipsometric Map, the topographies profiles and the longitudinal profile of the Paraíba do Sul River, was verified that this morphological feature is a regional drainage divided with NNW-SSE direction and a regional Knickpoint thats commands the erosion realized by the Paraíba do Sul River and his tributaries. The Hidrologic Map shows streams with abrupt changing of direction. Sometimes this direction continuous in streams of hidrological basins contiguous, originating relief lineaments, indicating stream capture. These stream captures happen in the tributaries of the Paraíba do Sul River with different direction of him, like the Calçado River that flows 20 km in the opposite direction up to his outfall in the property Paraíba do Sul River. These channels with opposite direction of the leading river suggest the existence of archaic mainly direction to West, thats being modified by the streams captures originated by the degrade of one paleo-divider that exists in the place where today is the Sapucaia Strait and divided the Paraíba do Sul River in two segments, ENE e WSW. This research, believes that this fact occurred at the Mesozoic/Cenozoic tectonic when was created structures that overlapped the olds structures that exists, reorganizing the distribution of the hydrologic flows. The inversion of the hydrologic flows increased the area of the Paraíba do Sul River enlarging the quantity of sediments that fills the Campos Basin. We expect, that this stream capture occurred in Meso-Eoceno when the Campos Basin stop to be starving and passes to receive a lot of sediments

A pesquisa teve como objetivo compreender o papel dos rearranjos de drenagem à evolução do relevo e da drenagem na bacia hidrográfica do Rio Capivari, situada no reverso da Serra do Mar, em São Paulo-SP. Parte-se da hipótese de que esses fenômenos seriam responsáveis por inúmeras anomalias de drenagem observadas, como: inflexões em ângulos retos, padrões de drenagem anômalos, colos, rupturas em perfis longitudinais e subdimensionamento de cursos dágua em relação aos vales. Especial ênfase foi dada à inflexão do alto Rio Capivari, localizada na confluência com o Ribeirão Embura, possível remanescente de uma captura fluvial, o qual melhor preserva as evidências de um rearranjo em toda a bacia. Os principais fatores dos rearranjos de drenagem na área foram: o forte gradiente hipsométrico proporcionado pela Serra do Mar, a densa trama de foliações e fraturas presentes no embasamento geológico, movimentações tectônicas recentes e as oscilações paleoclimáticas do Quaternário tardio. Sob influência dessas forças, alguns tributários da drenagem litorânea teriam se aproveitado de sua vantagem erosiva frente aos rios de planalto, produzido uma marcha de erosão regressiva em direção ao interior, com interferências nos canais situados em níveis sucessivamente mais elevados. Com base nas propostas metodológicas de Small (1972), Bishop (1995), Zaprowski et al. (2002) e Oliveira (2003), buscou-se a identificação de elementos morfológicos e sedimentológicos sugestivos desses processos, por meio de: análise de Modelos Digitais do Terreno (MDE) por métodos geomorfométricos; observação de fotografias aéreas; trabalhos de campo para descrição e coleta de materiais sedimentológicos; análise granulométrica, morfoscópica e mineralógica de sedimentos fluviais; e datação de sedimentos fluviais por Luminescência Óptica Estimulada para se estimar a idade da captura do alto curso do Rio Capivari. Os dados apresentados corroboram a hipótese de que o alto curso desse rio sofreu uma captura há cerca de 8.000 anos, no máximo, e que diversos outros casos de rearranjos de drenagem, entre eles reversões de grandes sistemas fluviais, seriam responsáveis pelas anomalias de drenagem observadas no interior da bacia estudada. / The aim of this research was to understand the role of drainage rearrangements on the evolution of relief and drainage in the Capivari River basin, located on the reverse of Serra do Mar range, in the state of São Paulo, Brazil. It is assumed that these phenomena would be responsible for numerous drainage anomalies observed, such as: river inflections at right angles, anomalous drainage patterns, cols, knickpoints and river underfitting, considered as indicative for drainage rearrangements. Special emphasis will be given to the inflection of the Capivari River at the confluence with the Ribeirao Embura, a possible remnant of a stream capture, which best preserves the evidence of a rearrangement throughout the basin. The main factors of the drainage rearrangements in the area would be: the strong hypsometric gradient provided by Serra do Mar range, the set of foliations and fractures densely present in the geological basement, recent tectonic movements and climatic oscillations of the Quaternary. Under the influence of these forcings, some tributaries of the coastal drainage would have taken erosive advantage over the plateau upside rivers, producing a regressive erosion march towards the interior of the continent, leading to interferences in the river systems situated at successively higher levels. Based on the methodological proposals of Small (1972), Bishop (1995), Zaprowski et al. (2002) and Oliveira (2003), we seek the identification of morphological and sedimentological elements that are suggestive of these processes, by means of: Digital Elevation Models (DEM) analysis by geomorphometric methods; observation of aerial photographs; fieldwork for description and collection of sedimentological materials; granulometric, morphoscopic and mineralogical analysis of fluvial sediments; and dating of fluvial sediments by Optically Stimulated Luminescence to estimate the age of capture of the upper reaches of the Capivari River. The presented data corroborate the hypothesis that the high course of the Capivari river was captured at least 8,000 years ago and that several other cases of drainage rearrangements, including reversals of large river systems, would be responsible for the observed drainage anomalies.