Risco hidrológico: precipitações extremas, enchentes e alagamentos na cidade de Ituiutaba (MG)
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Data
2017-11-10
Autores
Fonseca, Rogério Gerolineto [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
As inundações constituem um dos impactos ambientais mais observados nas áreas urbanas. A incidência destes eventos varia conforme as características climáticas e socioambientais das cidades. Esta pesquisa teve como objetivo principal avaliar o risco a enchentes, a alagamentos e ao escoamento superficial concentrado na área urbana de Ituiutaba (MG), a partir de suas condicionantes físicas e de suas características socioespaciais, inerentes ao processo de urbanização. Para isto, realizaram-se análises do geossistema urbano; da variabilidade pluvial com enfoque na recorrência das precipitações extremas; das ocorrências de transtornos associados ao impacto pluvial e da percepção do problema por parte da população atingida e do poder público municipal. Verificou-se que os impactos hidrometeóricos concentram-se durante os meses da primavera e do verão, quando as chuvas são mais abundantes. Em média, treze episódios chuvosos com volume a partir de 30mm/24h acontecem a cada ano, representando, assim, um potencial de danos ao ambiente urbano. De forma mais esporádica, acontecem ainda precipitações mais intensas, por volta de 90mm/24h, com potencial de impacto muito maior. Os arquivos das ocorrências do Corpo de Bombeiros e as reportagens publicadas pela imprensa local constituíram importantes fontes para o mapeamento e análise dos impactos. Como consequência desses eventos, tem-se na área central da cidade e bairros adjacentes, que são mais impermeabilizados, as ocorrências de escoamento superficial concentrado e os alagamentos. Além disso, a rede de galerias pluviais é insuficiente para drenar os locais onde os problemas são mais evidentes, principalmente em quatro áreas, sendo estas as avenidas José João Dib, Minas Gerais, Dezessete e Prof. José Vieira de Mendonça. Na primeira, observam-se alagamentos devido à deficiência na drenagem do escoamento superficial, que não consegue direcionar as águas para dentro da canalização do Córrego São José. Nos demais locais o problema é o escoamento superficial concentrado, que forma um fluxo ao longo das vertentes, suficiente para arrastar pessoas e veículos, além de provocar danos na pavimentação de ruas e calçadas. No tocante à população afetada pelas inundações, a maior parcela é formada por pessoas de baixa renda, cujas residências são mais vulneráveis ao acúmulo/escoamento de água em superfície. Este cenário demanda a atuação efetiva da administração pública no sentido de elaborar planos estratégicos para a gestão das águas pluviais.
Floods are one of the most observed environmental impacts in urban areas. The incidence of these events varies according to the climatic and socio-environmental characteristics of the cities. The main objective of this research was to evaluate the risk to the overflows, the floods and the concentrated surface runoff in the urban area of Ituiutaba (MG), based on its physical conditioning aspects and its socio-spatial characteristic, which are inherent in the urbanization process. For that purpose, some analyzes of the urban geosystem, the rainfall variability with focus on the recurrence of the extreme precipitations, the occurrences of disturbances associated with the rainfall impact and the perception of the problem by the affected population and the municipal public power were carried out. It was found that the hydrometeoric impacts are concentrated in the spring and summer months, when the rains are more abundant. On average, thirteen rainy episodes with a volume from 30mm/24h happen each year, which represents a potential for damages to the urban environment. More sporadically, there are some intense precipitations, around 90mm/24h, with a much greater potential impact. The Fire Department's archives and the news published in the local press were important sources for the mapping and analysis of the impacts. As a consequence of these events, there are in the city centre area and adjacent neighborhoods, which are more waterproofed spaces, the occurrences of concentrated surface runoff and flooding. In addition, the rain gutter network is insufficient to drain the places where the problems are more evident, mainly in four areas, which are the avenues José João Dib, Minas Gerais, Dezessete and Prof. José Vieira de Mendonça. At the José João Dib Avenue, floods are observed due to the deficiency in drainage of the surface runoff, that cannot direct the water into the canalization of the São José stream. In the other avenues, the problem is the concentrated runoff which forms a flow along the slopes that is enough to drag people and vehicles as well as cause damage to the paving of streets and sidewalks. With regard to the population affected by the floods, the majority is made up of low-income people, whose homes are most vulnerable to surface water accumulation / runoff. This scenario demands an effective action from the public administration in an effort to elaborate strategic plans for the management of the rainwater.
Floods are one of the most observed environmental impacts in urban areas. The incidence of these events varies according to the climatic and socio-environmental characteristics of the cities. The main objective of this research was to evaluate the risk to the overflows, the floods and the concentrated surface runoff in the urban area of Ituiutaba (MG), based on its physical conditioning aspects and its socio-spatial characteristic, which are inherent in the urbanization process. For that purpose, some analyzes of the urban geosystem, the rainfall variability with focus on the recurrence of the extreme precipitations, the occurrences of disturbances associated with the rainfall impact and the perception of the problem by the affected population and the municipal public power were carried out. It was found that the hydrometeoric impacts are concentrated in the spring and summer months, when the rains are more abundant. On average, thirteen rainy episodes with a volume from 30mm/24h happen each year, which represents a potential for damages to the urban environment. More sporadically, there are some intense precipitations, around 90mm/24h, with a much greater potential impact. The Fire Department's archives and the news published in the local press were important sources for the mapping and analysis of the impacts. As a consequence of these events, there are in the city centre area and adjacent neighborhoods, which are more waterproofed spaces, the occurrences of concentrated surface runoff and flooding. In addition, the rain gutter network is insufficient to drain the places where the problems are more evident, mainly in four areas, which are the avenues José João Dib, Minas Gerais, Dezessete and Prof. José Vieira de Mendonça. At the José João Dib Avenue, floods are observed due to the deficiency in drainage of the surface runoff, that cannot direct the water into the canalization of the São José stream. In the other avenues, the problem is the concentrated runoff which forms a flow along the slopes that is enough to drag people and vehicles as well as cause damage to the paving of streets and sidewalks. With regard to the population affected by the floods, the majority is made up of low-income people, whose homes are most vulnerable to surface water accumulation / runoff. This scenario demands an effective action from the public administration in an effort to elaborate strategic plans for the management of the rainwater.
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Palavras-chave
Risco hidrológico, Impactos pluviais, Alagamentos, Ituiutaba, Hydrological risk, Rainfall impacts, Floods