Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1974. / Bibliography: leaves 444-451. / xx, 451 leaves ill., maps

Research on hillslope surface processes and hillslope stratigraphy has been neglected in southern Africa. The amount of published literature on hillslope stratigraphy in southern Africa is very limited. Hillslope sediments provide a record of past environmental conditions and may be especially useful in calculating the recurrence interval of extreme environmental conditions such as earthquakes and intense rainfall events. The characteristics of hillslope sediments provide information as to their origin, transport and mechanisms of deposition. No published work could be found that had been undertaken on hillslope surface processes or stratigraphy in the eastern Cape coastal region. This study attempted to fill this gap in the geomorphic literature for southern Africa. The surface processes acting on hillslopes at Burchleigh and Spring Grove in the Alexandria district of the eastern Cape were examined in terms of slope morphology, surface sediment characteristics and the internal geometry of the hillslope sedimentary deposits. The late Quaternary hillslope sedimentary deposits at the two study sites are composed of fine grained colluvial sediments intercalated with highly lenticular diamicts. The fine grained colluvial sediments were emplaced by overland flow processes while the diamicts were deposited by debris flows. The sedimentary sequences at both study sites have a basal conglomerate interpreted as a channel lag deposit. Most slope failures preceding debris flow events were probably triggered by intense or extended periods of rainfall associated with cold fronts or cut-of flows. Seismic events may also have triggered slope failure, with or without the hillslope sediments being saturated. The results of this study indicate that a continuum exists between the slopewash dominated processes of the presently summer rainfall regions of Natal to the present winter rainfall regions of the western Cape where mass movement processes are significant. Hillslope deposits, therefore, provide a record of environmental conditions which may greatly facilitate proper management of the landscape.

Limestone and dolomite quarries were mapped to determine specific slope failure mechanisms for the various geological and structural conditions. Wedge failure and plane failure were determined to be the most influential mechanisms. Algorithms for analyzing these mechanisms were incorporated into the software package PSLOPE. The program is designed to facilitate progressive stability evaluation of quarry high walls as mining continues and permits calculation of safety factors and probabilistic reliability. Safety factor evaluations with the potential for back-analysis and sensitivity studies are included to investigate alternative high wall designs. Reliability analysis using Monte Carlo sampling minimizes uncertainty and allows the use of all available data in a stability evaluation. E~tensive "help" menus are incorporated into the program. The "help" menus include ranges of physical properties such as cohesion and friction angle for specific lithologic units determined from published research. This package includes an optimum design protocol that can be followed to avoid massive failure. The program was developed in conjunction with the quarry industry and is demonstrated through technical problem solving and a detailed case study. A large carbonate quarry in the eastern U.S. was studied in detail to demonstrate the utility of PSLOPE. / Master of Science

While the applications of Geographic Information Systems (GIS) have progressed from a descriptive tool to a decision making and modeling tool, the understanding of errors and variability of the components of a GIS has lagged behind. Slope is one of these components. This dissertation evaluates different methods for determining and characterizing slope values in polygons and how these methods affect natural resource models. Eight different previously used methods for determining cell slope values were compared using elevation data from the USGS Big Stone Gap, Virginia, Digital Elevation Model. The 28 pairwise comparisons were statistically different, but for practical applications six of the comparisons were similar with an average slope difference of less than one percent. In a decision model the effect of changing just the slope method used to determine cell slope values can influence the results of a model enough to cause almost a 10 fold difference. Since usually the smallest administered unit in natural resource management is the stand (polygon), nine ways of describing the slope of a polygon for 240 polygons using an aggregation of cell slope values were investigated. These polygon descriptors were mean, trim mean, median, mode, first quartile, third quartile, standard deviation, minimum and maximum cell slope value. Also, a new method of determining polygon slope was examined using trend surface techniques, which is not based on aggregation of single cell slope values. The distributions of cell slope values in a polygon cannot be assumed normal since few polygons had a normal distribution. The sensitivity of these polygon slope descriptors to polygon area and surface complexity, based on fractal dimension, was examined and found not to affect these polygon characteristics. The application and logical decisions required to choose an appropriate slope method and polygon slope descriptor(s) based on model objectives are shown in two examples, a harvesting and USLE model. Automating the process of choosing the appropriate polygon slope descriptor(s) and how to integrate these methods in an operational GIS using an Expert System is discussed. / Ph. D.

published_or_final_version / Geography and Geology / Master / Master of Philosophy

Title from PDF of title page. / Document formatted into pages; contains 123 pages. / Thesis (M.S.)--University of South Florida, 2001. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Simulating the processes of rainfall and runoff are at the core of hydrologic modeling. Geomorphologic features, rainfall variability, soil types, and water table depths strongly influence hydrological process in Florida ecosystems. Topographic characteristics of the terrain define the stream paths and landscape. Alteration of these characteristics as a result of urban and/or agricultural developments, for example, can highly influence wetlands and river basin response. There are two predominant landforms in Florida: wetlands, where Variable Saturated Areas form near streams causing saturation excess runoff, and uplands where runoff is mainly generated by infiltration excess. The objective of this work is to analyze the impacts of geomorphologic and hydrologic characteristics on runoff mechanisms in humid environments such as Florida. In general, most research at the hillslope scale use hypothetical values of rainfall, sometimes non-realistic values, and single slope forms to explain the geomorphic and hydrologic process on Variable Saturated Areas. In this thesis, the complexity of hillslope processes on actual Florida topography is assessed by coupling a Digital Elevation Model with a two-dimensional variable saturated-unsaturated flow model called HYDRUS-2D. Actual rainfall records and soil parameters from the Characterization Data for Selected Florida Soils, Soil Survey were used to evaluate hydrologic impacts. A commerical software package, River Tools was used to display and extract topographic information from the Digital Elevation Models.Results show that when inflitration excess runoff is dominant, infiltration and runoff are very sensitive to time resolution, especially for convective storms. When saturation excess occurs, runoff is not affected by rainfall intensity. However, saturated hydraulic conductivity, depth to the water table, slope and curvature highly influence the extent of Variable Saturated Areas. Results indicate runoff in shallow water table environments is produced mainly by subsurface storm runoff, running below the surface, except in hillslopes with concave curvature and mild slopes. Additionally, concave hillslopes generate more saturation excess runoff than straight and convex hillslopes. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

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The factors that influence the invasion of hillslopes by the shrub Pteronia incana in the communal rangelands of Ngqushwa (formerly Peddie) district were investigated. Mgwalana, one of the catchments in the district where encroachment by the species is widespread, was chosen. The study combined field observations with image analysis based on high resolution infrared imagery. The catchment was flown and high resolution infrared images (1mx1m) were taken using a Kodak DCS420 digital, colour-infrared camera. The images were analysed using Idrisi32 and Kilimanjaro GIS versions. The ability of different vegetation indices to separate P. incana from the other cover types was investigated. Field observations of the degree of P. incana invasion in relation to, inter alia, soil surface conditions, slope angle and visible forms of erosion were made. A Digital Elevation Model (DEM) of 20m spatial resolution was used to derive terrain parameters. The presence and absence of P. incana in relation to slope gradient and aspect were determined. The combined influence of the two terrain parameters and land use on the invasion was also investigated. The Topographic Wetness Index (WI), a component of the TOPMODEL was derived from the DEM and its relationship with the spatial distribution of P. incana was explored. Soil moisture dependencies for P. incana and grass species as well as surrogates for runoff under the shrub and adjacent bare areas were determined in the field. A high level of classification accuracy confirmed the reliability of digital camera imagery for spatial analyses. Distinct spectral separability for the surface vegetation cover types was achieved by means of the Perpendicular Vegetation Index (PVI) as opposed to the ratio based vegetation indices (NDVI, SAVI and MSAVI). The absence/presence of P. incana was noted to be strongly influenced by slope angle and aspect. The probability for P. incana occurrence increased with slope steepness and southerly slope orientation. Abandoned and grazing lands were identified as the main invasion hotspots. Blanket invasion of the former signified the high susceptibility of abandoned land to P. incana invasion. The combined influence of land use, slope gradient and aspect was also noted to have promoted the invasion. This is borne out by the concentration of the invasion on abandoned steep slopes with a southerly orientation. Local topographic variations were identified as having a strong bearing on P. incana spatial distribution. The topographically driven WI confirmed this relationship, such that P. incana was associated with the low WI values of convexities. Differences in the moisture dependencies between P. incana and grass species were demonstrated by the greater rooting depth of the former. During field surveys, soil surface crusting was noted as inherent to P. incana patchiness. The coupling between local topography and soil surface crusting underpins soil moisture variability at hillslope and patch scales respectively. This in turn determines the competition between P. incana and grass species and the eventual replacement of the latter by the former. A close spatial correlation between fully established P. incana and severe forms of soil erosion was observed. Loss of patchiness and expansion of inter-patch bare areas promote runoff connectivity erosion. As most of the runoff becomes run out, hillslopes tend towards dysfunctional systems. Greater soil moisture storage after rainstorms under P. incana tussocks than the adjacent bare areas signifies the shrub’s water harvesting capabilities. The tussocks could thus serve as a starting-pointbuilding- block for the rehabilitation of dysfunctional hillslope systems.

Orientador: Francisco Sérgio Bernardes Ladeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-16T07:15:01Z (GMT). No. of bitstreams: 1 Perdomo_CarolinaVerbicaro_M.pdf: 5534663 bytes, checksum: 34c27eac559f4a05a5c25e7a834561be (MD5) Previous issue date: 2010 / Resumo: Os movimentos de massa são fenômenos naturais de evolução das vertentes, mas eles causam grandes estragos sendo considerados como risco quando em uma área se têm a vulnerabilidade na escarpa associada a ocupação humana ou industrial que traga risco a população. A área de estudo fica localizada no litoral norte do Estado de São Paulo, Brasil. Na região da Serra do Mar, uma escarpa que chega aos 1.000m de altitude, funciona como uma barreira orográfica fazendo com que a área seja intensamente atingida por precipitações, sendo que o município atinge médias anuais muito altas. Para o estudo completo desses fenômenos é importante conhecer melhor a estrutura dos solos e seu comportamento em relação a dinâmica da água, por isso o objetivo deste trabalho foi de realizar esta caracterização e verificar o possível local de ruptura entre horizontes do solo. A área escolhida para o desenvolvimento do estudo têm altos índices pluviométricos e histórico desses tipos de movimentos de massa gravitacionais. Para a realização deste trabalho foram realizadas análises macromorfológicas de campo com descrição dos perfis levantados (três), de mineralogia, índices de Atterberg (limite de plasticidade e de liquidez), curva de retenção da água nos horizontes do solo e resistência ao cisalhamento. A granulometria analisada foi diversificada, encontrando solos argilosos e areno-argilosos, tendo predominância o Argissolo Vermelho Amarelo Álico. A maior profundidade encontrada foi de 227cm e a menor de 175cm; as curvas mostraram resultados de retenção diferentes para cada horizonte, mostrando os diferentes comportamentos em relação a retenção da água; os limites acompanharam a granulometria, tendo atingido valores maiores para solos mais argilosos, como os encontrados na trincheira 02; e a resistência ao cisalhamento também mostrou diferença nos valores dos parâmetros (coesão e ângulo de atrito interno) entre os horizontes, neste ensaio os solos da trincheira 03 não foram utilizados, pois ela estava localizada próxima a base da encosta. Os resultados nos levam a entender que o contato entre esses horizontes (B e C) é um ponto susceptível a ruptura / Abstract: The mass movements are natural phenomena of evolution of the slopes, but they cause great damage when being considered as a risk in one area if they have a vulnerability in the slope associated with human occupation or industry that brings risk population. The study area is located on the northern coast of São Paulo, Brazil. In the region of Serra do Mar, an escarpment that reaches 1,000 m above sea level, acts as an orographic barrier causing the area is heavily affected by rainfall, and the average annual county reaches very high. For the complete study of these phenomena is important to better understand the structure of soils and their behavior in relation to water dynamics, so the aim was to achieve this characterization and to determine the possible site of rupture between soil horizons. The area chosen for the development of study have high rainfall and history of these types of gravitational mass movements. For this work were analyzed macromorphological field describing the profiles surveyed (three), mineralogical, Atterberg limits (plastic limit and liquid), water retention curve in soil horizons and shear strength. The particle size analysis was diversified, finding clay soils and sandy-clay, with the predominance Alfissol Álico. The greatest depth found was less than 227cm and 175cm, the retention curves showed different results for each horizon, showing the different behaviors in relation to water retention; followed the grain boundaries, reaching higher values for more clayey soils, as those found in the trench 02, and shear strength also showed differences in the values of the parameters (cohesion and internal friction angle) between the horizons, to test the soil of the trench 03 were not used because it was located near the base of the slope. The results lead us to believe that contact between these horizons (B and C) is a point likely to break / Mestrado / Análise Ambiental e Dinâmica Territorial / Mestre em Geografia

Orientador: Regina Célia de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-18T07:13:22Z (GMT). No. of bitstreams: 1 Amorim_RaulReis_D.pdf: 119801790 bytes, checksum: 040d888f718cb48d6a1fd01d33281426 (MD5) Previous issue date: 2011 / Resumo: O estudo ambiental tem revelado sobretudo nas últimas décadas, um caráter interdisciplinar nas pesquisas pautadas sobre a dinâmica dos agentes naturais, frente à crescente pressão de uso do espaço, materializada por conflitos de diversas ordens, sejam esses, históricos, políticos, culturais, religiosos, enfim, relações humanas que se estruturam sobre o território e impõem a esse espaço níveis diversos de interferência no mecanismo natural preexistente. Nesse contexto, entender as relações das sociedades humanas com a natureza, dentro de uma perspectiva absolutamente dinâmica, que envolve os aspectos culturais, sociais, econômicos e naturais, exige adotar um procedimento analítico que leve em consideração a sociedade nos seus diversos estágios de desenvolvimento, e remeta a uma visão holística da organização do espaço. Sendo assim, a ciência geográfica, tendo como objeto de análise o espaço geográfico, possibilita, sob um olhar crítico, a realização de estudos ambientais integrados, de maneira a dar suporte técnico científico para a elaboração de estudos como aqueles relacionados ao zoneamento ambiental, que podem estar inseridos nas políticas públicas, contribuindo no planejamento e tomada de decisão. Considerando o exposto, esta tese se propõe à elaboração de um Zoneamento Ambiental, como subsidio ao planejamento do uso e ocupação das terras da zona costeira da região Costa do Descobrimento, situada na região Extremo Sul do Estado da Bahia. Tal proposta de estudo justifica-se por três fatores: (a) essa região é uma das áreas de povoamento pioneiro do território nacional, área em que o agente antrópico atua como ator na configuração da paisagem há mais de cinco séculos; (b) a área tem sofrido transformações no uso e ocupação das terras, não considerando os níveis de fragilidade ambiental da área em estudo, o que acentua os problemas ambientais; e (c) a inexistência de estudos que integrem os sistemas naturais aos sistemas antrópicos no planejamento no uso e ocupação da zona costeira da região Costa do Descobrimento. Nos últimos quarenta anos, ela se tornou uma das regiões mais dinâmicas economicamente do Estado da Bahia, e também é um dos principais destinos turísticos do Brasil. Para atingir tal meta, adotou-se a metodologia proposta por Rodriguez, Silva e Cavalcanti (2004), enfatizando a análise funcional da paisagem. As diferentes atividades econômicas implantadas na Região Costa do Descobrimento, nos últimos 40 anos possibilitaram a formação de diversos sistemas ambientais com fragilidades complexas e que sofrem há séculos pressões de uso, resultando em problemas ambientais que alteram a dinâmica dos sistemas naturais e também o modo de viver da população local / Abstract: The environmental study has revealed especially in recent decades in an interdisciplinary research guided on the dynamics of natural agents face the growing pressure of space usage, embodied by conflicts of various orders, are those, historical, political, cultural, religious, in order, human relations that are structured on the territory and impose on this space several levels of interference in the natural pre-existing mechanism. In this context, understanding the relationship of human societies and nature, within an absolutely dynamic perspective that involves cultural, social, economic and natural, requires adopting an analytical procedure that takes into account the society in their various stages of development, which refers to a holistic view of space organization. Thus, the geographical science as the object of the geographic analysis, allows a critical eye on the implementation of integrated environmental studies in order to provide technical support for the development of scientific studies such as those related to environmental zoning that can be inserted on policy contributing public in planning and decision taken. Considering the above, this thesis proposes the development of an environmental zoning as support for planning the use and occupation of the coastal region of the Discovery Coast, located in the extreme south of Bahia. This proposed study is justified by three factors: (a) this region is a pioneer of the populated areas of the country, an area in which the agent acts as man-made actor in shaping the landscape for more than five centuries, (b) area has undergone significant changes in the use and occupation of land, not considering the levels of environmental fragility of the study area, which emphasizes environmental issues, and (c) the lack of studies integrating natural systems to anthropogenic systems in use in planning and occupation of the coastal region of the Discovery Coast, that the last forty years has become one of the economically most dynamic regions of the state of Bahia, and is also one of the major tourist destinations in Brazil. To achieve this goal, we adopted the methodology proposed by Rodriguez, Cavalcanti, Silva and Cavalcanti (2004), emphasizing the functional analysis of the landscape. The different economic activities implemented in the Discovery Coast Region in the last 40 years has enabled the formation of different complex environmental systems with frailties and suffering centuries of use pressures resulting in environmental problems that affect the dynamics of natural systems and also the way of life of local population / Doutorado / Análise Ambiental e Dinâmica Territorial / Doutor em Ciências