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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

DinÃmica do balanÃo de energia na bacia hidrÃulica do aÃude OrÃs e suas adjacÃncias / Dynamics of the energy balance parameters around of the Oros Reservoir.

Francisco Dirceu Duarte Arraes 19 February 2010 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Este trabalho investiga a dinÃmica dos componentes do balanÃo de energia na Ãrea em torno e na bacia hidrÃulica do aÃude OrÃs nos Ãltimos 16 anos, pelo emprego do algoritmo SEBAL, bem como faz uma analise na relaÃÃo entre os calores sensÃvel e latente e o fluxo de calor do solo com as mudanÃas no uso do solo. Para tanto elaborou-se uma classificaÃÃo atual do uso e ocupaÃÃo da terra atravÃs da verdade de campo e da representaÃÃo de processos espaÃotemporais por meio de um conjunto de imagens TM â Landsat 5. As referidas imagens foram obtidas junto ao Instituto Nacional de Pesquisas Espaciais (INPE), as quais foram processadas e empilhadas pelo software Erdas IMAGINE 9.0. Em seguida aplicou-se o algoritmo SEBAL (Surface Energy Balance Algorithm for Land) para se quantificar o fluxo de calor latente a partir do resÃduo do balanÃo de radiaÃÃo da superfÃcie que tem como componentes a radiaÃÃo lÃquida (Rn), o fluxo de calor do solo (G) e o fluxo de calor sensÃvel (H). A classificaÃÃo supervisionada desenvolvida pelo mÃtodo mÃxima verossimilhanÃa mostrou um predomÃnio de vegetaÃÃo rala, ocupando aproximadamente 908,6 km2, correspondendo a 45,44% do total da Ãrea. Nesta classe està inserida a vegetaÃÃo herbÃcea arbustiva (porte baixo a mÃdio) aberta à densa, sendo esta classe a que apresenta maior vulnerabilidade à atuaÃÃo antrÃpica. O percentual da Ãrea de estudo que apresentou NDVI negativo para o ano de 2008 foi de 9,78%, nÃo mostrando diferenÃa entre o valor obtido para a percentagem de Ãgua pela classificaÃÃo supervisionada, expressando o potencial do NDVI para identificaÃÃo de corpos hÃdricos. A variabilidade temporal do fluxo de calor latente apresentou tendÃncia de reduÃÃo dos valores na Ãrea antropizada e consequentemente um aumento do fluxo de calor sensÃvel. / The main goal of this work was to study the dynamics of the energy balance parameters. The studied area was located around and in the OrÃs reservoir for 16 years. It was used the SEBAL algorithm, to provide an analysis of the relationship between the sensible and the latent heat and the heat flow in soil and the changes in land use. To reach this approach a classification to the use and occupation of land was developed. It was used the real data and the representation of space-time processes through a set of images TM - Landsat 5. These images were obtained from the Instituto Nacional de Pesquisas Especiais (INPE), which were processed and stacked by the software ERDAS IMAGINE 9.0. Then the SEBAL algorithm (Surface Energy Balance Algorithm for Land) was applied to quantify the latent heat flux from the residue of the radiation balance of the area. It was qualified the net radiation (Rn), the heat flow in soil (G) and sensible heat flux (H). Results showed that the supervised classification method developed by maximum likelihood identified a predominance of sparse vegetation, occupying approximately 908.6 km2, accounting for 45.44% of the total area. This class is composed for herbaceous shrub (low to medium-sized) open to dense, and this class has the highest vulnerability to anthropogenic activities. 9.78% of the studied area showed negative NDVI for the year 2008, this percentage also, was confirmed by the classification. This fact represents the potential of NDVI to identify the water bodies. The temporal variability of the components of energy balance didnât present tendency of increase or decrease and it was strongly influenced by the rainfall distribution. The components of energy balance didnât allow the identification of changes in the land use around the OrÃs reservoir.

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