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Otimização da rede de acessos a zonas de risco de incêndio na floresta do Vale do Sousa
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Orientador(es)
Resumo(s)
Os incêndios florestais podem ter consequências desastrosas para a economia, para o ambiente e
para a vida humana. Estes tendem a ser cada vez mais frequentes, tornando a sua prevenção e combate
problemas prementes a resolver. As estradas florestais são a infraestrutura base que permite o acesso dos
bombeiros aos locais dos incêndios. No entanto, o planeamento destas tem sido maioritariamente feito
com base no seu papel na atividade produtiva ou recreativa das florestas.
O objetivo deste trabalho foi determinar a melhor rede de estradas a construir de modo a garantir a
acessibilidade a todo a floresta do Vale do Sousa com o menor custo. Considerou-se que uma área está
acessível se existir uma estrada até 200 metros desta, e estudaram-se duas definições de distância. Foram
utilizados modelos de fluxo orientado para chegar a uma solução e compararam-se os resultados obtidos
quando a proteção de cada área é assegurada por um caminho único ou por dois caminhos disjuntos.
Concluiu-se que a forma como é calculada a distância tem um grande impacto na solução obtida,
principalmente por poder alterar a área acessível mais do que por fazer variar os custos. Como seria
de esperar, a solução com dois caminhos implica um maior custo, mas cria uma rede de estradas mais
resiliente ao combate aos incêndios e mais segura para os bombeiros. No entanto, nem sempre é possível
a construção de caminhos inteiramente disjuntos tornando o problema impossível. Uma adaptação do
problema promovendo a existência de um caminho alternativo mas sem o impor seria uma abordagem
interessante para estudos futuros.
Forest fires can have disastrous consequences for the economy, the environment and human life. These tend to be increasingly frequent, making their prevention and combat issues to be promptly addressed. Forest roads are the basic infrastructure that allow firefighters to access fire locations. However, road planning has mostly been done based on their role in the forests productive or recreational activities. The objective of this work was to determine the best road network to build in order to guarantee accessibility to the entire Vale do Sousa forest at the lowest cost. It was considered that an area is accessible if there is a road within 200 meters, and two definitions of distance were studied. Oriented network flow models were used to reach a solution, and the results were compared between protection ensured by a single path or by two disjoint paths. It was possible to conclude that the way in which the distance is calculated has an impact on the solution obtained, mainly because it changes the accessible area rather than by changing the costs. As expected, the two-path solution is more expensive but creates a road network that is more resilient to fire fighting and safer for the firefighters. However, it is not always possible to construct entirely disjoint paths, which makes the problem impossible to solve. An adaptation of the problem, promoting the existence of an alternative path, but without imposing it, would be an interesting approach for future studies.
Forest fires can have disastrous consequences for the economy, the environment and human life. These tend to be increasingly frequent, making their prevention and combat issues to be promptly addressed. Forest roads are the basic infrastructure that allow firefighters to access fire locations. However, road planning has mostly been done based on their role in the forests productive or recreational activities. The objective of this work was to determine the best road network to build in order to guarantee accessibility to the entire Vale do Sousa forest at the lowest cost. It was considered that an area is accessible if there is a road within 200 meters, and two definitions of distance were studied. Oriented network flow models were used to reach a solution, and the results were compared between protection ensured by a single path or by two disjoint paths. It was possible to conclude that the way in which the distance is calculated has an impact on the solution obtained, mainly because it changes the accessible area rather than by changing the costs. As expected, the two-path solution is more expensive but creates a road network that is more resilient to fire fighting and safer for the firefighters. However, it is not always possible to construct entirely disjoint paths, which makes the problem impossible to solve. An adaptation of the problem, promoting the existence of an alternative path, but without imposing it, would be an interesting approach for future studies.
Descrição
Tese de Mestrado, Estatística e Investigação Operacional, 2023, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Estradas florestais Incêndios florestais Construção estradas Modelo de programação linear inteira misto Modelo de fluxo orientado Teses de mestrado - 2023