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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The use of remote sensing data for assessing water quality in wetlands within the Limpopo River Basin

Dzurume, Tatenda January 2021 (has links)
>Magister Scientiae - MSc / Wetlands are unique ecosystems that are acknowledged among the world’s most productive and valuable ecosystems. They are recognized as being essential to sustainable development and human welfare due to their unique environmental and socio-economic value. These highly productive ecosystems provide functions such as recycling of nutrients, watershed protection and flood control as well as grazing resources. Wetlands provide the basis for human livelihoods in Africa through ecosystem services. However, these ecosystems are affected by internal and external factors within and outside their catchments, hence the importance of monitoring those changes around these wetlands.
2

Remote sensing and multispectral imaging of hydrological responses to land use/land cover and climate variability in contrasting agro-ecological systems in Mountainous catchment, Western Cape

Govender, Tanushri January 2022 (has links)
>Magister Scientiae - MSc / Water is a fundamental resource and key in the provision of energy, food and health. However, water resources are currently under severe pressure as a consequence of climate change and variability, population growth and economic development. Two driving factors that affect the availability of water resources are land use land cover (LULC) change and climate variability. Increasing population influences both LULC change and climate variability by inducing changes in key hydrological parameters such as interception rates, evapotranspiration (ET), run-off, surface infiltration, soil moisture, water quality and groundwater availability thereby affecting the watershed hydrology. The effects of LULC change and climate variability on hydrologic parameters have been extensively studied.
3

The use of remote sensing data for assessing water quality in wetlands within the Limpopo River Basin

Dzurume, Tatenda January 2021 (has links)
>Magister Scientiae - MSc / Wetlands are unique ecosystems that are acknowledged among the world’s most productive and valuable ecosystems. They are recognized as being essential to sustainable development and human welfare due to their unique environmental and socio-economic value. These highly productive ecosystems provide functions such as recycling of nutrients, watershed protection and flood control as well as grazing resources. Wetlands provide the basis for human livelihoods in Africa through ecosystem services. However, these ecosystems are affected by internal and external factors within and outside their catchments, hence the importance of monitoring those changes around these wetlands. The aim of this study was to identify the major land use and land cover changes (LULC) from two selected wetlands (i.e. Makuleke and Nyslvei) and their impacts on water quality within the Limpopo Transboundary River Basin, South Africa. To achieve this aim, firstly the study assessed the impacts of LULC changes on these two wetlands between 2014 and 2018. Multi-date Landsat series data were used to map and estimate the rate of LULC changes in Makuleke and Nylsvlei wetland ecosystems during the study period. The results obtained showed that the spatial extent of Makuleke declined by 2% between 2014 and 2018, whereas the Nylsvlei wetland decreased by 3%. Some of the noticeable changes were that the coverage of natural vegetation tends to increase during the wet seasons. Secondly, Chlorophyll-a was predicted and mapped for Makuleke and Nysvlei between September 2018 and June 2019. Moderate resolution Landsat 8 images and in-situ field measurements were used to estimate and map chlorophyll-a concentrations from these two wetlands. Landsat-derived chlorophyll-a concentrations were validated using field-derived chlorophyll-a measurements. The results showed a variation of chl-a concentration in these two wetlands, with Makuleke wetlands concentrations ranging from 0 to 1.15 μg/L whereas for Nylsvlei wetland the ranges varied between 0 and 1.42μg/L. The finding of this study can be used in enforcing of wetland legislation and LULC management practices and highlights the relevance of remotely sensed data in assessing and routine monitoring wetland water quality.
4

Padrões de uso e cobertura do solo na Floresta Nacional do Tapajós e seu entorno / Use and land cover patterns in the Tapajós National Forest and its surroundings

Lisbôa, Leila Sheila Silva 15 July 2015 (has links)
A crescente pressão sobre os recursos naturais tem motivado pesquisadores a desenvolver metodologias e adoção de novas ferramentas para avaliar as principais forçantes de mudanças de uso e cobertura do solo e propor estratégias de mitigação em áreas antrópicas com baixa produtividade na Amazônia. Práticas conservacionistas como uso de sistemas de produção apresentam-se como alternativas capazes de apontar indicadores de sustentabilidade em consonância com políticas públicas para a região. As Unidades de Conservação - UCs são criadas para resguardar a integridade dos ecossistemas, a biodiversidade e os serviços ambientais de cada paisagem e retardar o avanço do desmatamento. Neste sentido, o objetivo do presente trabalho foi avaliar padrões na paisagem na Floresta Nacional do Tapajós e seu entorno capazes de identificar a dinâmica de uso e cobertura do solo, períodos de alta e baixa intensidade de mudanças, heterogeneidade da paisagem e conectividades funcionais. Foram utilizadas quatro metodologias: análises quantitativas de mudança identificando perdas e ganhos; intensidade anual de mudanças, fragmentação por meio de métricas da paisagem; conectividade funcional, entre a matriz da UC e os fragmentos florestais em seu entorno. A área de estudo foi dividida em três subáreas: Floresta Nacional do Tapajós (FNT); Zona de Amortecimento (ZA); e Área de Influência (AI). Foram utilizadas imagens do satélite Landsat dos anos de 1986, 1997, 2005 e 2009. Avaliou-se a dinâmica de mudança em matriz de transição detalhada (perdas, ganhos, mudança líquida, permuta de mudança, intensidade anual de mudança). No sistema computacional Fragstats calculou-se índices métricos da paisagem. No ambiente SIG foi gerada a distância de menor custo utilizada no sistema Conefor. No Conefor foram gerados os índices de conectividade funcional. Com base nos quatro mapas de uso e cobertura do solo obtidos, referente aos anos de avaliações, verificou-se que pelo método tradicional de análise de padrões, as áreas com Floresta Nativa (FN) dentro da Flona Tapajós praticamente não variaram (3,1%), indicando a manutenção da conectividade funcional na UC. Todavia, na Zona de Amortecimento (ZA) e Área de Influência (AI), as perdas foram de 41,3% de Floresta Nativa (FN). Ao aplicar metodologias com maior análise de sensibilidade verificou-se que na parte norte da área de estudo existe menor probabilidade de conectividade com a Flona Tapajós. Conclui-se que as reduções de manchas florestais começaram na parte norte da área de estudo, também evidenciada pela intensificação dos caminhos de perdas de conectividade funcional nas áreas mais próximas a Belterra, onde localizam-se os cultivos de grãos. A Floresta Nacional do Tapajós apresenta maior conectividade com a parte sul, ou seja, existe maior probabilidade de conectividade funcional com o município de Rurópolis. / Growing pressure on natural resources has motivated researchers to develop methodologies and new tools to assess the main driving forces of land cover and land use change and to come up with mitigation strategies in low productivity populated areas of the Amazon. Conservation practices, such as the use of production systems, have appeared as alternatives able to point out sustainability indicators in line with the region\'s public policies. Conservation Units (UC) are designed to protect the ecosystems integrity, biodiversity and each landscape\'s ecosystem services, as well as to slow down deforestation. In this context, this study\'s aim was to assess landscape patterns in the Tapajós National Forest and its surroundings that would be able to identify the dynamics of land use and land cover, periods of high and low intensity of change, landscape heterogeneity and functional connectivity. Four methodologies were used: quantitative analyses of change by identifying losses and gains; annual intensity of change; fragmentation through landscape metrics; functional connectivity between the UC headquarters and the forest around it. Our study area was divided into three sub-areas: the Tapajós National Forest (FNT), the Buffer Zone (ZA) and the Area of Influence (AI). Also, we used Landsat satellite images from the years 1986, 1997, 2005 and 2009. We assessed the change dynamics in detailed transition matrix (losses, gains, net change, change permutation, annual intensity of change). In the computer system Fragstats, we calculated the landscape metric indexes. In the GIS, we generated the lowest cost distance used in the Conefor system. In the Conefor system, we generated the functional connectivity indexes. Based on the four maps of land use and land cover we obtained for the years we decided to assess, we found through the traditional method of pattern analysis, that areas with Native Forest (FN) within the Tapajós National Forest almost did not change (3.1 %), indicating a maintenance of functional connectivity within the UC. However, in the Buffer Zone (ZA) and Area of Influence (AI), losses amounted to 41.3% of the Native Forest (FN). By applying methodologies with greater sensibility analysis, we found that the northern part of the study area had less possibilities of connectivity with the Tapajós National Forest. To conclude, the reduction of forest patches began in the northern part of the study area, also evidenced by the intensification of functional connectivity loss paths in areas close to Belterra, where are located grain crops. The National Forest presents greater connectivity with the southern part, in other words, there are more possibilities of functional connectivity with the Rurópolis municipality.
5

Padrões de uso e cobertura do solo na Floresta Nacional do Tapajós e seu entorno / Use and land cover patterns in the Tapajós National Forest and its surroundings

Leila Sheila Silva Lisbôa 15 July 2015 (has links)
A crescente pressão sobre os recursos naturais tem motivado pesquisadores a desenvolver metodologias e adoção de novas ferramentas para avaliar as principais forçantes de mudanças de uso e cobertura do solo e propor estratégias de mitigação em áreas antrópicas com baixa produtividade na Amazônia. Práticas conservacionistas como uso de sistemas de produção apresentam-se como alternativas capazes de apontar indicadores de sustentabilidade em consonância com políticas públicas para a região. As Unidades de Conservação - UCs são criadas para resguardar a integridade dos ecossistemas, a biodiversidade e os serviços ambientais de cada paisagem e retardar o avanço do desmatamento. Neste sentido, o objetivo do presente trabalho foi avaliar padrões na paisagem na Floresta Nacional do Tapajós e seu entorno capazes de identificar a dinâmica de uso e cobertura do solo, períodos de alta e baixa intensidade de mudanças, heterogeneidade da paisagem e conectividades funcionais. Foram utilizadas quatro metodologias: análises quantitativas de mudança identificando perdas e ganhos; intensidade anual de mudanças, fragmentação por meio de métricas da paisagem; conectividade funcional, entre a matriz da UC e os fragmentos florestais em seu entorno. A área de estudo foi dividida em três subáreas: Floresta Nacional do Tapajós (FNT); Zona de Amortecimento (ZA); e Área de Influência (AI). Foram utilizadas imagens do satélite Landsat dos anos de 1986, 1997, 2005 e 2009. Avaliou-se a dinâmica de mudança em matriz de transição detalhada (perdas, ganhos, mudança líquida, permuta de mudança, intensidade anual de mudança). No sistema computacional Fragstats calculou-se índices métricos da paisagem. No ambiente SIG foi gerada a distância de menor custo utilizada no sistema Conefor. No Conefor foram gerados os índices de conectividade funcional. Com base nos quatro mapas de uso e cobertura do solo obtidos, referente aos anos de avaliações, verificou-se que pelo método tradicional de análise de padrões, as áreas com Floresta Nativa (FN) dentro da Flona Tapajós praticamente não variaram (3,1%), indicando a manutenção da conectividade funcional na UC. Todavia, na Zona de Amortecimento (ZA) e Área de Influência (AI), as perdas foram de 41,3% de Floresta Nativa (FN). Ao aplicar metodologias com maior análise de sensibilidade verificou-se que na parte norte da área de estudo existe menor probabilidade de conectividade com a Flona Tapajós. Conclui-se que as reduções de manchas florestais começaram na parte norte da área de estudo, também evidenciada pela intensificação dos caminhos de perdas de conectividade funcional nas áreas mais próximas a Belterra, onde localizam-se os cultivos de grãos. A Floresta Nacional do Tapajós apresenta maior conectividade com a parte sul, ou seja, existe maior probabilidade de conectividade funcional com o município de Rurópolis. / Growing pressure on natural resources has motivated researchers to develop methodologies and new tools to assess the main driving forces of land cover and land use change and to come up with mitigation strategies in low productivity populated areas of the Amazon. Conservation practices, such as the use of production systems, have appeared as alternatives able to point out sustainability indicators in line with the region\'s public policies. Conservation Units (UC) are designed to protect the ecosystems integrity, biodiversity and each landscape\'s ecosystem services, as well as to slow down deforestation. In this context, this study\'s aim was to assess landscape patterns in the Tapajós National Forest and its surroundings that would be able to identify the dynamics of land use and land cover, periods of high and low intensity of change, landscape heterogeneity and functional connectivity. Four methodologies were used: quantitative analyses of change by identifying losses and gains; annual intensity of change; fragmentation through landscape metrics; functional connectivity between the UC headquarters and the forest around it. Our study area was divided into three sub-areas: the Tapajós National Forest (FNT), the Buffer Zone (ZA) and the Area of Influence (AI). Also, we used Landsat satellite images from the years 1986, 1997, 2005 and 2009. We assessed the change dynamics in detailed transition matrix (losses, gains, net change, change permutation, annual intensity of change). In the computer system Fragstats, we calculated the landscape metric indexes. In the GIS, we generated the lowest cost distance used in the Conefor system. In the Conefor system, we generated the functional connectivity indexes. Based on the four maps of land use and land cover we obtained for the years we decided to assess, we found through the traditional method of pattern analysis, that areas with Native Forest (FN) within the Tapajós National Forest almost did not change (3.1 %), indicating a maintenance of functional connectivity within the UC. However, in the Buffer Zone (ZA) and Area of Influence (AI), losses amounted to 41.3% of the Native Forest (FN). By applying methodologies with greater sensibility analysis, we found that the northern part of the study area had less possibilities of connectivity with the Tapajós National Forest. To conclude, the reduction of forest patches began in the northern part of the study area, also evidenced by the intensification of functional connectivity loss paths in areas close to Belterra, where are located grain crops. The National Forest presents greater connectivity with the southern part, in other words, there are more possibilities of functional connectivity with the Rurópolis municipality.

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