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Canais artificiais e a sua influĂȘncia em processos de planeamento urbano e ordenamento territorial
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Abstract(s)
Os fenĂłmenos de cheia decorrentes de intempĂ©ries tĂȘm ao longo do tempo assolado o arquipĂ©lago da Madeira, particularmente a ilha da Madeira a qual se diferencia, entre outras, pelo seu relevo acentuado. Estas caraterĂsticas, associadas aos fenĂłmenos de cheia, conduzem a dezenas de vĂtimas mortais, centenas de afetados direta ou indiretamente e milhares de milhĂ”es em custos monetĂĄrios associados. Insurge-se deste modo como prioritĂĄria, a necessidade de simular com o maior rigor possĂvel o escoamento das linhas de ĂĄgua com maior relevĂąncia neste tipo de catĂĄstrofes, articulando com os princĂpios de planeamento urbano em vigor na regiĂŁo de modo a procurar minimizar os seus riscos e consequĂȘncias.
As linhas de ĂĄgua que atravessam ĂĄreas urbanas podem ser classificadas como canais artificiais. Relativamente ao canal natural, as artificiais, introduzem diversas caraterĂsticas diferentes tais como: largura, profundidade e rugosidade, Camacho (2018). A temĂĄtica em anĂĄlise, considera a necessidade de efetuar uma modelação numĂ©rica das linhas de ĂĄgua â isto Ă©, a simulação das condiçÔes de escoamento nas ribeiras da RegiĂŁo AutĂłnoma da Madeira (RAM), de modo a permitir um ordenamento do territĂłrio e planeamento urbano mais apropriados, garantindo assim a segurança da população, bem como a preservação de bens materiais.
A anålise do escoamento verificado nas ribeiras da RAM assume-se como fundamental, tendo em vista a redução de riscos em fenómenos de cheia bem como das respetivas åreas de inundação, sendo para isso particularmente relevante a anålise de sensibilidade de diversos parùmetros tais como: fórmulas de transporte sólido, coeficientes de Manning-Strickler, condiçÔes de fronteira a montante, distribuição granulométrica nas diversas secçÔes transversais consideradas e caudais afluentes.
Os canais artificiais, deveriam condicionar a predisposição do tecido urbano de qualquer cidade, regiĂŁo ou paĂs uma vez que em casos extremos de precipitação, eles sĂŁo os principais responsĂĄveis pelo correto escoamento minimizando qualquer tipologia de risco associado a cheias. Contudo o que acontece dĂ©cada apĂłs dĂ©cada Ă© uma continua ocupação urbana na proximidade das principais linhas de ĂĄgua, tendo a agravante de esta se intensificar mais a jusante o que obviamente promove um acrĂ©scimo Ă sua perigosidade â uma vez que, estas zonas sĂŁo as mais propĂcias a serem afetadas por enxurradas e/ou cheias atravĂ©s do galgamento dos leitos das ribeiras. Considerando que a ilha da Madeira Ă© periodicamente afetada por chuvas de alta intensidade, associadas Ă sua urografia, assume-se como fundamental que os vĂĄrios instrumentos de gestĂŁo territorial contemplem, como mĂnimo uma carta de risco municipal utilizando ferramentas como os SIG, bem como, condicionando a forma como se desenvolve o planeamento e respetivo ordenamento do territorial.
Por outro lado, começam a ser postos em prĂĄtica os mecanismos anteriormente descritos nos concelhos onde as enxurradas/cheias/aluviĂ”es tĂȘm protagonizado um maior impacto negativo, nomeadamente quanto Ă criação (e inclusĂŁo no respetivo PDM) da carta de risco de cheias e inundaçÔes da Ribeira Brava, a inclusĂŁo das ĂĄreas em risco ou ameaçadas por cheias na planta de ordenamento II do PDM do Funchal e, ainda da publicação no Jornal Oficial da RegiĂŁo AutĂłnoma da Madeira (JORAM) da criação do Plano de GestĂŁo dos Riscos de InundaçÔes da RAM (PGRI-RAM).
Weather-related flooding phenomena have over time plagued the Madeira archipelago, particularly the island of Madeira, which is distinguished, among others, by its marked relief. These characteristics, associated with flood phenomena, lead to dozens of fatalities, hundreds directly or indirectly affected and billions in associated monetary costs. Thus, the need to simulate the flow of the most relevant waterlines in such disasters is a priority to minimize their risks and consequences, as well as to articulate urban planning principles already effective in the region of Madeira. Waterlines running through urban areas can be classified as artificial canals. Regarding the natural channels, the artificial ones introduce several different characteristics such as width, depth or roughness, Camacho (2018). The theme under consideration explores the need to perform numerical modeling of the waterlines - that is, the simulation of flow conditions in the watercourses of the Autonomous Region of Madeira (RAM), to carry out proper spatial and urban planning, thus ensuring the safety of the population as well as the preservation of its goods. The analysis of the runoff in the RAM watercourses is fundamental in order to reduce the risk of flooding, as well as the respective flood-prone areas, being particularly relevant the analysis of several parameters such as: solid transport equations, Manning-Strickler coefficients, upstream boundary conditions, particle size distribution alongside the waterlines considered and tributary flows. Artificial water channels should condition the predisposition of the urban fabric of any city, region or country since in extreme cases of precipitation, they are primarily responsible for the correct drainage minimizing any risk typology associated with floods. However, it seems obvious that decade after decade, the urbanization of the vicinity of the main watercourses and the aggravation of its intensification taking place downstream increase the danger - since these areas are the most prone to be affected by floods through the overflow of the stream beds. Considering that Madeira is periodically affected by high-intensity rainstorms associated with its urography, it is assumed that the various territorial management instruments must include, at minimum a municipal risk map using tools such as GIS, as well as conditioning the way how the urban and the respective territorial planning are developed. On the other hand, the mechanisms previously described are beginning to be implemented in the municipalities where floods have had a major negative impact, particularly with the creation (and inclusion in the respective PDM) of the flood risk map in Ribeira Brava, the inclusion of flood-prone areas in the FunchalÂŽs PDM management plan II and also the publication of the creation of Flood Risk Management Plans (PGRI-RAM) in the Official Journal of the Autonomous Region of Madeira (JORAM).
Weather-related flooding phenomena have over time plagued the Madeira archipelago, particularly the island of Madeira, which is distinguished, among others, by its marked relief. These characteristics, associated with flood phenomena, lead to dozens of fatalities, hundreds directly or indirectly affected and billions in associated monetary costs. Thus, the need to simulate the flow of the most relevant waterlines in such disasters is a priority to minimize their risks and consequences, as well as to articulate urban planning principles already effective in the region of Madeira. Waterlines running through urban areas can be classified as artificial canals. Regarding the natural channels, the artificial ones introduce several different characteristics such as width, depth or roughness, Camacho (2018). The theme under consideration explores the need to perform numerical modeling of the waterlines - that is, the simulation of flow conditions in the watercourses of the Autonomous Region of Madeira (RAM), to carry out proper spatial and urban planning, thus ensuring the safety of the population as well as the preservation of its goods. The analysis of the runoff in the RAM watercourses is fundamental in order to reduce the risk of flooding, as well as the respective flood-prone areas, being particularly relevant the analysis of several parameters such as: solid transport equations, Manning-Strickler coefficients, upstream boundary conditions, particle size distribution alongside the waterlines considered and tributary flows. Artificial water channels should condition the predisposition of the urban fabric of any city, region or country since in extreme cases of precipitation, they are primarily responsible for the correct drainage minimizing any risk typology associated with floods. However, it seems obvious that decade after decade, the urbanization of the vicinity of the main watercourses and the aggravation of its intensification taking place downstream increase the danger - since these areas are the most prone to be affected by floods through the overflow of the stream beds. Considering that Madeira is periodically affected by high-intensity rainstorms associated with its urography, it is assumed that the various territorial management instruments must include, at minimum a municipal risk map using tools such as GIS, as well as conditioning the way how the urban and the respective territorial planning are developed. On the other hand, the mechanisms previously described are beginning to be implemented in the municipalities where floods have had a major negative impact, particularly with the creation (and inclusion in the respective PDM) of the flood risk map in Ribeira Brava, the inclusion of flood-prone areas in the FunchalÂŽs PDM management plan II and also the publication of the creation of Flood Risk Management Plans (PGRI-RAM) in the Official Journal of the Autonomous Region of Madeira (JORAM).
Description
Keywords
Escoamento Instrumentos de gestĂŁo territorial Ordenamento territorial Sistemas de informação geogrĂĄfica Flow Territorial management instruments Spatial planning Urban planning Geographic information systems Engenharia Civil . Faculdade de CiĂȘncias Exatas e da Engenharia