Thesis (M.S.)--West Virginia University, 2005 / Title from document title page. Document formatted into pages; contains viii, 138 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references (p. 81-85).

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains viii, 89 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 79-81).

Resumo: O rio Paraná, em seu trecho natural, possui padrão multicanal caracterizado por canais secundários de diferentes ordens, separando diversas ilhas e barras fluviais. As barras fluviais são formas semi-submersas associadas à disponibilidade de sedimentos e a um dinamismo temporal cujas dimensões são controladas pelo fluxo e pela profundidade. Neste estudo, pretende-se compreender os processos que promovem a formação, desenvolvimento e movimentação de uma barra de soldamento situada junto à ilha Santa Rosa, no rio Paraná, município de Porto Rico - PR. Para alcançar os objetivos propostos, foram realizados levantamentos de parâmetros hidráulicos, morfométricos e granulométricos. Nos dados levantados dos parâmetros hidráulicos, verificou-se que a presença da ilha Santa Rosa, juntamente com barra fluvial, divide o canal em dois setores de dinâmica hidráulica e sedimentar distintas. O canal principal conduz a maior parcela da vazão, é mais energético, enquanto o canal secundário apresenta valores inferiores nestes dois parâmetros. A separação do fluxo também acarreta na formação de correntes divergentes à direção principal do canal, favorecendo a diminuição da velocidade e, consequentemente, a deposição de sedimentos no entorno da ilha Santa Rosa. Averiguou-se que a morfologia da barra está diretamente vinculada às flutuações de vazão do rio Paraná: em período de águas altas há maior retrabalhamento da forma, já no período de águas médias, esta se preservou parcialmente, inclusive com afloramento em parte. Quanto aos sedimentos, as partículas de diâmetro fino distribuem-se em locais de maior velocidade de fluxo e profundidade (talvegue) em ambos os períodos analisados As partículas de diâmetro médio a grosso encontram-se no período de águas altas distribuídas pela área estudada; já no período de águas médias, estes sedimentos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Paraná River, in its natural stretch, has a multichannel pattern characterized by secondary channels of different orders, which separates several islands and bars. The bars are forms semi-submerged associated with the availability of sediment and a temporal dynamic, whose dimensions are controlled by the flow and depth. This study intends to understand the processes which promote formation, development and movement of the annexation bar associated to the Santa Rosa Island, located on Paraná River, near to Porto Rico - PR. To achieve the proposed aims, surveys were carried out in hydraulic, morphometric and granulometric parameters. In the data hydraulic parameters survey it was found that the presence of Santa Rosa Island along with bar divides the river channel in two sectors of distinct dynamic hydraulic and sediment. The main channel leads to a higher portion of the flow, it is more energetic, while the secondary channel has lower values in these two parameters. The separation of the flow also causes the formation of divergent currents towards the main channel, favoring the decrease in velocity and consequent deposition of sediments near to Santa Rosa Island. It was found that the morphology of the bar is directly linked to fluctuations in the flow of the Paraná River, during periods of high water there is more reworking, since in this average water period partially preserved its shape, emerging in part. As for sediment, the fine diameter particles are distributed in areas of higher flow velocity and depth (thalweg) in both analyzed periods. From medium to coarse diameter particles are, in the high-water period, distributed in the studied area, although in the average water period these sediments are located in low flow velocity and depth (Bar and Secondary Channel). Specific stream power and shields parameter values are larger in the main channel in both periods, indicating... (Complete abstract click electronic access below) / Orientador: José Cândido Stevaux / Coorientador: Mario Luis Assine / Banca: Paulo Fernando Soares / Banca: Antônio Roberto Saad / Mestre

abstract: The San Gabriel Mountains (SGM) of southern California provide the opportunity to study the topographic controls on erosion rate in a mountain range where climate and lithology are relatively constant. I use a combination of digital elevation model data, detailed channel survey data, decadal climate records, and catchment-averaged erosion rates quantified from 10Be concentrations in stream sands to investigate the style and rates of hillslope and channel processes across the transition from soil-mantled to rocky landscapes in the SGM. Specifically, I investigate (1) the interrelations among different topographic metrics and their variation with erosion rate, (2) how hillslopes respond to tectonic forcing in "threshold" landscapes, (3) the role of discharge variability and erosion thresholds in controlling the relationship between relief and erosion rate, and (4) the style and pace of transient adjustment in the western SGM to a recent increase in uplift rate. Millennial erosion rates in the SGM range from 0.03-1.1 mm/a, generally increasing from west to east. For low erosion rates (< 0.3 mm/a), hillslopes tend to be soil-mantled, and catchment-averaged erosion rates are positively correlated with catchment-averaged slope, channel steepness, and local relief. For erosion rates greater than 0.3 mm/a, hillslopes become increasingly rocky, catchment-mean hillslope angle becomes much less sensitive to erosion rate, and channels continue to steepen. I find that a non-linear relationship observed between channel steepness and erosion rate can be explained by a simple bedrock incision model that combines a threshold for erosion with a probability distribution of discharge events where large floods follow an inverse power-law. I also find that the timing of a two-staged increase in uplift rate in the western SGM based on stream profile analysis agrees with independent estimates. Field observations in the same region suggest that the relict topography that allows for this calculation has persisted for more than 7 Ma due to the stalling of migrating knickpoints by locally stronger bedrock and a lack of coarse sediment cover. / Dissertation/Thesis / Ph.D. Geological Sciences 2011

In this paper we present a joint initiative of the Instituto Geológico Minero y Metalúrgico (Ingemmet) and the Research Group of Physical Geography in High Mountains of the Universidad Complutense de Madrid (GFAM-UCM), to promote at Peru the research on geomorphology and climate change. The plan is to elaborate geomorphological maps of Lima Metropolitana and header watersheds (Chillón, Rímac and Lurín), to generating analytical instruments to achieve the following objectives: 1) Decoding the record of climatic changes in landforms. 2) Delimit water reserves stored as ice masses (cryosphere). 3) Recognize the relationship between the geomorphology and the geological hazards which may affect to people and their economic activities. 4) Design a methodology that can be extrapolated to other Peruvian regions. To this end, geomorphological mapping will be integrated into geographic information systems (GIS): will be identified the morphoclimatic units and the related genetic processes. Also, their relative chronologies will be proposed. Then, the absolute dating of key units will be established to confirm or correct the relative chronologies. The information will be compiled in databases to be contrasted with other evidences and paleoclimatic proxies. This is intended to produce models of climate evolution, to contribute to the assessment of geological hazards, and the knowledge of current state of cryosphere, including recent trends and future forecasts. / En este trabajo se presenta una iniciativa conjunta del Instituto Geológico Minero y Metalúrgico (Ingemmet) y el Grupo de Investigación en Geografía Física de Alta Montaña de la Univeridad Complutense de Madrid (GFAM-UCM) para promover en el Perú las investigaciones sobre geomorfología y cambio climático. El plan consiste en elaborar mapas geomorfológicos de la región de Lima Metropolitana y las cabeceras de sus cuencas hidrográficas (Chillón, Luríny Rímac) generando instrumentos de análisis para: 1) Decodificar el registro de los cambios climáticos en las formas del relieve. 2) Delimitar las reservas hídricas almacenadas en forma de masas de hielo (criosfera), conocer sus tendencias y elaborar pronósticos de futuro. 3) Identificar las relaciones entre las geoformas del relieve y los peligros geológicos que afectan a la población y sus actividades económicas. 4) Diseñar una metodología que pueda extrapolarse a otras regiones peruanas. Con el fin de lograr esos objetivos, en primer lugar se van a elaborar mapas geomorfológicos integrados en sistemas de información geográfica (SIG): se diferenciarán las unidades morfoclimáticas, se identificarán los procesos que las generaron y se propondrán sus cronologías relativas. A continuación, se establecerán las cronologías absolutas de unidades clave, que permitirán confirmar o corregir la anterior secuencia de edades. De este modo se desea contribuir a desarrollar modelos de la evolución del clima, colaborar con la evaluación de los peligros geológicos y conocer el estado de la criosfera, incluyendo tendencias pasadas y previsiones futuras.

Anthropogenic climate change significantly affects water resources. River flows in mountainous regions are driven by snowmelt and are therefore highly sensitive to increases in temperature resulting from climate change. Climate-driven hydrological changes are potentially significant for the fluvial geomorphology of river systems. In unchanging climatic and tectonic conditions, a river's morphology will develop in equilibrium with inputs of water and sediment, but climate change represents a potential forcing on these variables that may push the system into disequilibrium and cause significant changes in river morphology. Geomorphic factors, such as channel geometry, planform, and sediment transport, are major determinants of the value of river systems, including their suitability for threatened and endangered species and for human uses of water. This dissertation research uses a hierarchical modeling approach to investigate potential impacts of anthropogenic climate change on river morphology in the interior Pacific Northwest. The research will address the following theoretical and methodological objectives: 1) Develop downscaled climate change scenarios, based on regional climate-model output, including changes in daily minimum and maximum temperature and precipitation. 2) Estimate how climate change scenarios affect river discharge and suspended-sediment load, using a basin-scale hydrologic model. 3) Examine potential impacts of climate-driven hydrologic changes on stream power and shear stress, bedload sediment transport, and river morphology, including channel geometry and planform. The downscaling approach, based on empirically-estimated local topographic lapse rates, produces high-resolution climate grids with positive forecast skill. The hydrologic modeling results indicate that projected climate change in the study rivers will change the annual cycle of hydrology, with increased winter discharge, a decrease in the magnitude of the spring snowmelt peak, and decreased summer discharge. Geomorphic modeling results suggest that changes in reach-averaged bedload transport are highly sensitive to likely changes in the recurrence interval of the critical discharge needed to mobilize bed sediments. This dissertation research makes an original contribution to the climate-change impacts literature by linking Earth processes across a wide range of spatial scales to project changes in river systems that may be significant for management of these systems for societal and ecological benefits. This dissertation includes unpublished co-authored material.

The Willamette is a gravel-bed river that drains ~28,800 square kilometers between the Coast Range and Cascade Range in northwestern Oregon before entering the Columbia River near Portland. In the last 150 years, natural and anthropogenic drivers have altered the sediment transport regime, drastically reducing the geomorphic complexity of the river. The purpose of this research is to assess longitudinal trends in sediment transport within the modern flow regime. Sediment transport rates are highly discrete in space, exhibit similar longitudinal patters across flows and increase non-linearly with flow. The highest sediment transport rates are found where the channel is confined due to disconnection of the floodplain and the river runs against high resistance terraces. The spatial distributions of sediment transport rates and active gravel are tightly linked. Sediment sampling revealed slight downstream fining in the surface grain size. Sediment size did not correlate with stream power.

Recent advances in through-water photogrammetry and optical imagery indicate that accurate, continuous bathymetric mapping may be possible in shallow, clear streams. This research directly compares the ability of through-water photogrammetry and spectral depth approaches to extract water depth for monitoring fish habitat. Imagery and cross sections were collected on a 140 meter reach of the Salmon River, Oregon, using an unmanned aerial vehicle (UAV) and rtk-GPS. Structure-from-Motion (SfM) software produced a digital elevation model (DEM) (1.5 cm) and orthophoto (0.37 cm). The photogrammetric approach of applying a site-specific refractive index provided the most accurate (mean error 0.009 m) and precise (standard deviation of error 0.17 m) bathymetric data (R2 = 0.67) over the spectral depth and the 1.34 refractive index approaches. This research provides a quantitative comparison between and within bathymetric mapping methods, and suggests that a site-specific refractive index may be appropriate for similar gravel-bed, relatively shallow, clear streams.

abstract: This research examines lateral separation zones and sand bar slope stability using two methods: a parallelized turbulence resolving model and full-scale laboratory experiments. Lateral flow separation occurs in rivers where banks exhibit strong curvature, for instance canyon rivers, sharp meanders and river confluences. In the Colorado River, downstream Glen Canyon Dam, lateral separation zones are the principal storage of sandbars. Maximum ramp rates have been imposed to Glen Canyon Dam operation to minimize mass loss of sandbars. Assessment of the effect of restricting maximum ramp rates in bar stability is conducted using multiple laboratory experiments. Results reveal that steep sandbar faces would rapidly erode by mass failure and seepage erosion to stable slopes, regardless of dam discharge ramp rates. Thus, continued erosion of sand bars depends primarily of turbulent flow and waves. A parallelized, three-dimensional, turbulence resolving model is developed to study flow structures in two lateral separation zones located along the Colorado River in Grand Canyon. The model employs a Detached Eddy Simulation (DES) technique where variables larger than the grid scale are fully resolved, while Sub-Grid-Scale (SGS) variables are modeled. The DES-3D model is validated using ADCP flow measurements and skill metric scores show predictive capabilities of simulated flow. The model reproduces the patterns and magnitudes of flow velocity in lateral recirculation zones, including size and position of primary and secondary eddy cells and return current. Turbulence structures with a predominately vertical axis of vorticity are observed in the shear layer, becoming three-dimensional without preferred orientation downstream. The DES-3D model is coupled with a sediment advection-diffusion formulation, wherein advection is provided by the DES velocity field minus particles settling velocity, and diffusion is provided by the SGS. Results show a lateral recirculation zone having a continuous export and import of sediment from and to the main channel following a pattern of high frequency pulsations of positive deposition fluxes. These high frequency pulsations play an important role to prevent an oversupply of sediment within the lateral separation zones. Improved predictive capabilities are achieved with this model when compared with previous two- and three-dimensional quasi steady and steady models. / Dissertation/Thesis / Appendix C Video 3.1 / Appendix C Video 3.2 / Appendix C Video 3.3 / Appendix C Video 3.4 / Appendix C Video 3.5 / Appendix C Video 3.6 / Appendix C Video 3.7 / Appendix F Video 4.1.a / Appendix F Video 4.1.b / Appendix F Video 4.2 / Doctoral Dissertation Geography 2015

Made available in DSpace on 2014-06-11T19:24:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-08Bitstream added on 2014-06-13T20:31:13Z : No. of bitstreams: 1 almeida_bt_me_prud.pdf: 10697930 bytes, checksum: 7bb7b517178fdfe6a047f9d628c0ff22 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Uma vez que é mais freqüente a cada dia o direcionamento de fortes investimentos para o resgate das potencialidades dos ambientes naturais, devido constantes agressões disseminadas pelo modelo de desenvolvimento adotado nos últimos séculos, este trabalho tem como objetivo o estudo dos aspectos físicos e a dinâmica dos agentes sociais que atuam na área da bacia hidrográfica do ribeirão Palmito, localizada no município de Três Lagoas (MS). Assim, o presente trabalho visa à busca de uma leitura dinâmica da paisagem através das características estruturais e ecológicas da bacia, da leitura espaço-sazonal de alguns componentes do regime hidrológico e hidrossedimentológico, além da caracterização do uso do solo ocupação do relevo. As investigações realizadas e a avaliação da existência ou não de desequilíbrios na paisagem da bacia estudada considerou as características naturais por meio da dinâmica do canal fluvial, assim como os fatores geomorfológicos, geo-pedológicos e hidrológicos da bacia, baseado principalmente no fato de que os materiais podem ser facilmente erodidos em função dos solos frágeis e bastantes espessos da região. Além disso, os fatores que transformam a paisagem através dos tipos de utilização... / A time that is more frequent to each day the aiming of strong investments for the rescue of the potentialities of natural environments, had constant aggressions spread for the model of development adopted in the last centuries, this research has as objective the study of the physical aspects and the dynamics of the social agents that act in the area of the hydrographic basin of the Palmito stream, located in the Três Lagoas city (MS). Thus, the present work aims at to the search of a dynamic reading of the landscape through the structural and ecological characteristics of the basin, of the reading space-seasonably of some components of the hydrologic and hydrossedimentologic regimen, beyond the characterization of the use of the ground and occupation of the relief. The investigations realized and the evaluation of the existence or not of disequilibria in the landscape of the studied basin did not consider the natural characteristics by means of the dynamics of the fluvial canal, as well as the geomorphologics factors, geopedologics and hydrologics of the basin, based mainly on the fact of that the materials can easily be eroded in function of the fragile grounds and sufficiently thick. Moreover, the factors that transform the landscape ... (Complete abstract click electronic access below)