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Impacto estrutural de cheias pluviais, considerando abordagens uni e bidimensionais na modelação de escoamentos superficiais em ambiente urbano
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Abstract(s)
A urbanização altera o uso do solo de uma bacia hidrográfica: as áreas permeáveis diminuem e as impermeáveis aumentam, fazendo com que menor quantidade de precipitação infiltre no solo. Ao associar o crescimento urbano com os eventos hidrológicos extremos e redes de drenagem projetadas para o cenário anterior ao da urbanização, pode-se ter como consequência as cheias urbanas.
Uma cheia provoca diversos danos diretos e indiretos, e.g., na saúde da população, na economia e no patrimônio construído. O alvo desta dissertação é estudar o impacto de uma cheia urbana em construções existentes, infraestruturas, áreas agricultadas e nas zonas rurais. O fenômeno da cheia urbana ocorre principalmente devido à chuva intensa e ao sistema de drenagem que entra em carga. Neste cenário, o escoamento é impedido de entrar no sistema de drenagem e forçado a escoar na superfície, causando danos nas regiões atingidas. A água de uma inundação provoca várias ações que podem ter origem física, química ou biológica e que impactam um patrimônio construído de forma mais amena ou até mesmo a destruição total.
Para a realização do estudo deste impacto, utilizou-se a modelação hidrológica e hidráulica. Este tipo de modelação vem sendo utilizada nas últimas décadas para o dimensionamento da rede de drenagem, prevenir riscos e corrigir condicionantes urbanas estruturais que frequentemente resultam em cheias. Foram utilizadas duas aplicações computacionais para realizar a modelação, o SWMM (unidimensional) e o Iber (bidimensional). Admitiu-se como cenário um evento extremo, correspondente a um período de retorno de 100 anos. Com os resultados obtidos nas aplicações computacionais, realizou-se o estudo dos danos através do método das curvas profundidade-dano, que fornece os danos estruturais e não estruturais em valores monetários.
O estudo de caso incidiu sobre a vila de Cabanas de Tavira, ao sul de Portugal, devido a sofrer recorrentemente de cheias com origem em precipitações intensas de curta duração.
Urbanization changes the land use of a catchment, as permeable areas decrease and impervious areas increase, causing less precipitation to infiltrate into the soil. By associating urban growth with extreme hydrological events and drainage networks designed for pre-urbanization scenarios, flooding can be a resulting hazard. An urban flood can cause direct and indirect damages on different levels as it can compromise the health, the economy, and the heritage of a city. The overarching aim of this dissertation is to study the structural impact of the urban flood on buildings, infrastructures, and agricultural areas. The urban flood phenomenon usually happens because of short-duration high-intensity rainfall events over an ineffective stormwater drainage system. In this scenario, runoff is prevented from entering the drainage system and forced to flow back to the surface, causing damage to the affected areas. The flood water affects the existing buildings through physical, chemical, and biological factors, and can cause major damages and even the complete destruction of large areas. The flood impact was analyzed by hydrological and hydrodynamic computational simulations, a somewhat common procedure to quantify and characterize flood prone areas thus mitigating flood risk. In this study two software packages were used: SWMM and Iber; both were set on an extreme 100-years flood scenario, considering a surcharged stormwater system, thus not contributing to drain the study case area. The tidal effect in the Ria Formosa coastal lagoon was also considered as a boundary condition. The results obtained from the computational simulation are used to make a preliminary evaluation of the flood impact using depth-damage curves, which provided the structural and non-structural damage in terms of economic losses. The case study is in Cabanas de Tavira, in the south of Portugal, prone to historical flood events.
Urbanization changes the land use of a catchment, as permeable areas decrease and impervious areas increase, causing less precipitation to infiltrate into the soil. By associating urban growth with extreme hydrological events and drainage networks designed for pre-urbanization scenarios, flooding can be a resulting hazard. An urban flood can cause direct and indirect damages on different levels as it can compromise the health, the economy, and the heritage of a city. The overarching aim of this dissertation is to study the structural impact of the urban flood on buildings, infrastructures, and agricultural areas. The urban flood phenomenon usually happens because of short-duration high-intensity rainfall events over an ineffective stormwater drainage system. In this scenario, runoff is prevented from entering the drainage system and forced to flow back to the surface, causing damage to the affected areas. The flood water affects the existing buildings through physical, chemical, and biological factors, and can cause major damages and even the complete destruction of large areas. The flood impact was analyzed by hydrological and hydrodynamic computational simulations, a somewhat common procedure to quantify and characterize flood prone areas thus mitigating flood risk. In this study two software packages were used: SWMM and Iber; both were set on an extreme 100-years flood scenario, considering a surcharged stormwater system, thus not contributing to drain the study case area. The tidal effect in the Ria Formosa coastal lagoon was also considered as a boundary condition. The results obtained from the computational simulation are used to make a preliminary evaluation of the flood impact using depth-damage curves, which provided the structural and non-structural damage in terms of economic losses. The case study is in Cabanas de Tavira, in the south of Portugal, prone to historical flood events.
Description
Keywords
Cheias urbanas Impacto estrutural Escoamento superficial Curvas profundidade-dano Modelação uni e bidimensional