This study describes the impacts of river development projects on land use and vegetation in a floodplain that includes old-growth forest and an important primate habitat located in eastern Kenya. River basin development activities include the construction of hydro-electric dams in the upper river basin, and an irrigation scheme, the Bura Irrigation and Settlement Project, in the lower basin. Through flood frequency analysis for both the pre- and post-dam period, I demonstrate that there has been a significant (p < 0.01) reduction in floods with a recurrence interval of 5 years or greater. A hydrological simulation model is used to estimate the frequency and duration of flooding of 73 vegetation sample plots for the pre- and post-dam period. Four of the plots, lying less than 1.25 m above dry season river level, show a slight increase in days flooded, whereas the rest show a significant decline in days flooded from the pre- to the post-dam period. Detailed descriptions of the structure and dynamics of the Tana riverine forest, and exploration into the influence of abiotic variables to species composition, are made using ordination and classification techniques. The three canopy levels examined, and the regeneration layer, had different species compositions. Many of the upper canopy species are not regenerating. Results of detailed land cover and change detection mapping using remotely sensed data reveal significant change. Forest cover declined slightly (about 2%) between 1975 and 1984. However, between 1989 and 1996, there was a 27% decline in riverine forest, while cultivated area within the forest increased by 45%. Over the same period, area of exposed soil increased by 112%. Several landscape measures are given and all indicate significant fragmentation of riverine forest. The extent of riverine forest along the active river channel declined by about 200 m between 1989 and 1996. Human disturbance now represents the greatest threat to continued survival of the forest. Results of a dendrochronologie investigation reveal that a number of species produce growth rings. Four species identified as offering the best chance for developing a ring-width chronology are; Acacia elatior, Acacia robusta, Tamarindus indica, and Newtonia hildebrandtii.

Changes in land use and land cover are a global issue of concern, especially with regard to possible impacts on biophysical processes which affect the hydrological functioning of a system. Tanzania is no exception to this concern. This study, therefore, addresses the implications of land use alterations on the hydrodynamics of the Kilombero River Basin, specifically with regard to the Kilombero Valley’s wetlands and water resources, which have been altered and exploited to a great extent. As its starting point, the study embarked on mapping the current land cover in the Kilombero Basin and the quantification of the historical changes. The study revealed significant changes and, in recent years, increased rates of clearing natural vegetation cover and conversion to agricultural land. The most affected area of the Basin was the Kilombero Valley, a Ramsar Site and formerly extensively inhabited by wildlife, but which now has 62% of its area converted into agricultural and/or human settlements. In line with this observation, the study used two approaches for the impact analysis, a regional scale and a local scale approach. Plant physiology, soil moisture and micro-meteorological measurements were undertaken to quantify the impact of land cover change at local scale. Sensing techniques were then applied to assess the spatial extent of the changes and the basin scale (regional) impact thereof. Investigation of hydrological processes at a local scale placed emphasis on the implications of forest conversion from indigenous Miombo woodland to exotic Teak (Tectona grandis) forests. Field measurements showed the distinctive nature of Teak trees consumptive water use, both in quantity as well as in regard to the seasonal variation as compared to the native Miombo woodland forests. Teak was found to have higher transpiration rates, both during the rainy season (where the rates were approximately 10-fold higher than that of Miombo) and the period immediately after the cessation of rainfall, with consumptive water use rates being four-fold higher than that of Miombo. This contrast in water use was further observed in the measured soil water fluxes which evidenced a large difference in the components of the soil water balance. Less recharge was observed in the Teak forests suggesting significant impacts on the replenishment of groundwater resources in the study area. Assessment of the basin scale impacts of the land cover changes on the evapotranspiration (ET) regime was undertaken using the Surface Energy Balance System (SEBS) remote sensing model. Validation was provided by the Teak field sites and through the monitoring of ET from sugar cane using a Large Aperture Scintillometer (LAS). Results suggest a decrease in ET during the dry season. There is a clear transition of ET that follows the land cover transition from the natural and more adaptable vegetation, to rain-fed dependent crops and bare lands, where minimal ET is observed during the dry season. Similar seasonal leafing, and therefore a similar ET pattern, is observed with the conversion of natural forests to deciduous plantation forests. Irrigated crops, on the other hand, were found to have persistently higher ET throughout the year regardless of rainfall variability. This implies that land cover change in the Kilombera Valley is resulting in higher water use and less recharge in the wet season and a correspondingly lower ET (and possibly lower river flow) in the dry season than would occur under natural conditions. This research provides valuable information relevant to all stakeholders in the Kilombero River Basin (i.e. both smallholders and commercial sugarcane farmers, the forestry industry, Basin Water Authorities etc.). This information will help to inform decision-making around the sustainable management of the water resources in the Kilombero Valley for food security as well as for sustaining livelihoods and ecosystems. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

Orientador: Antonio Carlos Vitte / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-11T16:26:46Z (GMT). No. of bitstreams: 1 Mello_JulianoPereirade_M.pdf: 2084983 bytes, checksum: 6e2923138c220c23483e5caf7f4635fd (MD5) Previous issue date: 2008 / Resumo: Este trabalho apresenta um ensaio cartográfico para a determinação da fragilidade ambiental na Bacia Hidrográfica do Rio Verde (SP), a qual está localizada numa área de contato entre as rochas cristalinas da Serra da Mantiqueira e os terrenos sedimentares da Depressão Periférica Paulista. Procedemos na construção de um apanhado conceitual e metodológico definindo e explorando os conceitos de planejamento e gestão, susceptibilidade, sensibilidade, fragilidade e vulnerabilidade ambientais. Analisamos as características histórico-social-econômicas da Bacia Hidrográfica do Rio Verde (SP), a qual é marcada pelas práticas agropecuárias, principalmente, as ligadas aos plantios de cana-de-açúcar, batata e cebola, além da criação de gado bovino. Mapeamos e analisamos os dados sobre geologia, pedologia, drenagem, hipsometria, declividades e de uso e ocupação das terras, os quais, foram tratados em ambiente SIG e integrados por um algoritmo para chegarmos a um mapa síntese das classes de fragilidade ambiental na Bacia Hidrográfica do Rio Verde (SP). O mapa síntese revela que, da área total da Bacia Hidrográfica do rio Verde, 13,23% estão classificados como sendo de muito baixa fragilidade, 42,13% como sendo de baixa fragilidade, 22,17% como sendo de média fragilidade, 14,15% como sendo de alta fragilidade e 8,31% como sendo de muito alta fragilidade ambiental. Concluímos que a maior parte da área formada pela junção das classes de média a muito alta fragilidade estão na porção da bacia hidrográfica que corresponde aos domínios da Serra da Mantiqueira ¿ maior intensidade dos processos de morfogênese / Abstract: This work presents a cartographic essay to determination of environmental fragility in the watershed of the Rio Verde (SP), localized in a contact area between crystalline rocks of the Serra da Mantiqueira and sedimentary terrains of the Depressão Periférica Paulista. We achieve the construction of a conceptual and methodological caught defining and exploring the concepts of environmental planning and management, susceptibility, sensibility, fragility and vulnerability. Analyzed the historical-social-economic characteristics watershed of the Rio Verde (SP), which is marked for the agriculture practices, principally, the connected at potato, onion, sugar cane planting, over there of livestock creation. Mapped and analyzed about geology, pedology, drainage, hypsometric, declivities and terrain use and occupation dates, which went treatise in a SIG environment and integrated for a algorithm to arrive the a synthesis map of the fragility environmental classes in the watershed of Rio Verde (SP). The synthesis map show that, of the total area of watershed of Rio Verde, 13,23% are classify as very decrease fragility, 42,13% as decrease fragility, 22,17% average fragility, 14,15% as high fragility and 8,31% as very high fragility. Then, conclude that the major part of area formed to the add of the average to very high fragility classes are in the portion of the Serra da Mantiqueira ¿ major intensity of the morphogenetic process / Mestrado / Análise Ambiental e Dinâmica Territorial / Mestre em Geografia

Orientador: Diógenes Cortijo da Costa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-25T02:22:07Z (GMT). No. of bitstreams: 1 Corghi_FernandaNascimento_D.pdf: 10660154 bytes, checksum: 8373162d0c4c68cb5636f2a1de96435e (MD5) Previous issue date: 2013 / Resumo: O loteamento abrange, além dos lotes, uma parte da gleba destinada a equipamentos urbanos e comunitários (de educação, cultura, saúde, lazer e similares) e áreas livres de uso público. Cabe ao poder público estabelecer porcentagens e impedir a ocupação de áreas de risco. Por isso, conhecer a hidrologia e a geomorfologia da bacia hidrográfica é importante para harmonizar o projeto à superfície topográfica e prevenir impactos decorrentes de rupturas no sistema natural. A terraplenagem efetuada para locação do empreendimento, associada à concentração do fluxo de água sub e superficial pelas ruas e galerias de drenagem, acelera processos de erosão. O solo carreado assoreia sistemas de drenagem e as enchentes se configuram como um dos impactos cumulativos decorrentes deste padrão de ocupação. Os impactos sociais são sentidos pela destruição de obras civis e riscos à vida humana. Neste sentido, as diretrizes exigidas pelo poder público devem ser seguidas para garantir o uso das áreas públicas e particulares ao fim a que se destinam.O objetivo desta tese é propor critérios físicos e sociais condizentes com o comportamento do substrato físico local e com os avanços sociais da Política Urbana como requisitos urbanísticos para projetos de loteamentos. Correlacionamos arranjos da forma urbana física elementar (rua, quadras, lotes, etc) em conformidade com os apontamentos da cartografia geocientífica preventiva de impactos ambientais. Estabelecemos como estudo de caso uma bacia hidrográfica do município de Bauru (SP); analisamos a possibilidade de inclusão da cartografia geotécnica de prevenção à erosão como instrumento norteador de loteamentos menos impactantes. A partir da constatação de que (i) a escala de confecção da cartografia geocientífica tende a ser realizada em pequenas e médias escalas e (ii) a escala utilizada para Planos Diretores e empreendimentos urbanísticos é necessariamente a grande escala, estabelecemos nossa proposta metodológica a partir da adoção de uma unidade física condizente aos planejamentos urbanos e geocientíficos. Partimos da setorização da vertente da bacia hidrográfica (em pelo menos três partes) para tornar possível a correlação de elementos do sistema natural (físico) e antrópico (urbano). Chamamos esta correlação de "unidade geo-urbanística". O funcionamento das unidades geo-urbanísticas em uma vertente da bacia hidrográfica estudada forneceu diferentes magnitudes de impacto para cada unidade a depender dos arranjos antrópicos nela estabelecidos. A simulação do funcionamento da vertente ofertou sete cenários de impacto, posto que diferentes arranjos de elementos urbanos estabelecem diferentes maneiras de ampliar tendências a impactos próprias do setor da vertente. Os cenários foram extrapolados para a bacia hidrográfica como um todo. Acreditamos que, com a utilização da unidade geo-urbanística como suporte à criação de cenários de impacto, seja possível definir requisitos urbanísticos para loteamentos. Desta maneira, também evita-se que a destinação de áreas públicas se dê em locais com maior suscetibilidade a impactos na bacia hidrográfica. Estes avanços foram consolidados na tese ao propormos alterações na legislação de parcelamento do solo (6.766/79) incorporando uma nova conceituação para "gleba" e uma maior participação pública direta tendo por escopo o uso da propriedade urbana "em prol do bem coletivo" (10.257/01, Art. 1º) / Abstract: The allotment covers, in addition to lots, part of the glebe aimed at urban and community facilities (education, culture, health, leisure and related) and open areas for public use. It is the public authority which establishes percentages and prevents the occupation of risk areas. Therefore, knowing the hydrology and geomorphology of the watershed is important to harmonize the project to the topographic surface and prevent impacts resulting from disruptions in the natural system. The earthwork made to lease the venture, related to the sub and superficial concentration of water flow on streets and drainage galleries, accelerates erosion processes. The adduced soil silts drainage systems and flooding is configured as one of the cumulative impacts of this pattern of occupation. The social impacts are felt by the destruction of civil works and risks to human life. In this sense, the guidelines required by public authorities must be followed to ensure the use of public and private areas to the purpose which they are intended. The aim of this thesis is to propose physical and social criteria consistent with the behavior of the local physical substrate and the social advances of Urban Policy as urban requirements for projects of settlements. We correlated arrangements of elementary physical urban form (street, blocks, lots, etc.) in accordance to the appointments of geoscientific cartography preventive of environmental impacts. We established as a case study a watershed in the city of Bauru (SP); we analyze the possibility of inclusion of geotechnical cartography to the erosion prevention as the guiding instrument of less impactful allotments. From the verification that (i) the scale of confection of geoscientific cartography tends to be performed in small and medium scales and (ii) the scale used for Directive Plans and urban ventures is necessarily large scale, we established our methodological proposal from the adoption of a consistent physical unit to urban and geoscientific planning. We started from the watershed slope (in at least three parts) to make it possible the correlation of elements of the natural (physical) and anthropogenic (urban) system. We call this correlation "geo-urban unit". The functioning of the geo-urban units in one watershed slope studied provided different magnitudes of impact for each unit depending on the anthropic arrangements established therein. The simulation of the functioning of the slope offered seven impact scenarios, since different arrangements of urban elements establish different manners of expanding the trends to the impacts specific of the sector of the slope. The scenarios were extrapolated to the watershed as a whole. We believe that with the use of geo-urban unit as a support to the creation of impact scenarios, it is possible to define urban requirements for settlements. Thus, it also avoids that the allocation of public areas is given in places with greater susceptibility to impacts in the watershed. These advances were consolidated in the thesis by proposing changes in legislation of land subdivision (6.766/79) incorporating a new conceptualization of "glebe" and greater direct public participation with the purpose to the use of urban property "in favor of the common good" (10.257/01, Article 1) / Doutorado / Saneamento e Ambiente / Doutora em Engenharia Civil

Upland peat catchments are usually assumed to function as carbon sinks, however, there have been extensive studies witnessing increasing trends in concentrations and fluxes of organic carbon in UK rivers over the last few decades. A number of controls on dissolved organic carbon (DOC) release from peatlands, such as climatic changes and landuse management, have been proposed. This study examines the effects of land use and management on organic carbon exports in the Dyke catchment of the River Halladale (northern Scotland) with a nested catchment approach. This study provides insight into the processes controlling the DOC dynamics in the Dyke catchment, and the impact of disturbance caused by landuse changes such as afforestation and tree felling for restoration. The results from factor analysis, end-member mixing, absorbance (E4/E6), and hysteresis analyses on stream water chemistry from individual sub-catchments identified the major hydrological pathways during storm events, and based on these results, conceptual models were developed to explain DOC evolution during storm events. At all the sites studied, nearsurface soil water was identified as the major controlling end-member for stream DOC concentrations. The calculated annual flux of DOC from the Dyke catchment, up-scaled from the results of the individual sub-catchments, is 521.6 kg C ha-1 yr-1, which is significantly (~5 times) higher than the previously published value (103.4 kg C ha-1 yr-1) for the River Halladale catchment (Hope et al., 1997). In this study, it is shown that about 57 - 95% of the DOC export occur during 5 - 10% of the high flows, therefore, it is crucial that quantitative records of DOC export are developed using high frequency storm event measurements, as well as lower frequency low flow sampling. Climatic changes related to precipitation, temperature, coupled with water yield capacity of the sub-catchments, are identified as significant controls on DOC fluxes, rather than landuse change, as the intact site releases more organic carbon per unit area compared to the disturbed and re-wetted site undergoing restoration. In addition, the results from this study provide landowners, policy makers and organisations with the evidence they require for initiating future peatland restoration works, as felling of forestry coupled with drain-blocking is shown to be an effective restoration technique that may help a catchment to eventually return to a near-pristine state.