A methodology for flood risk assessment for two cities in Nigeria
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Data
2023-08-11
Autores
Babajide, Emmanuel Inioluwa
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
As inundações/enchentes são consideradas uma das ameaças mais comuns à vida humana e às propriedades. A avaliação da vulnerabilidade e da suscetibilidade é a primeira etapa do gerenciamento do risco de inundação uma vez que é vital que pode ajudar os formuladores de políticas a identificar e implementar políticas que minimizem o risco de ocorrências. Esta pesquisa tem como objetivo desenvolver uma metodologia usada para mapear duas cidades selecionadas no sudoeste da Nigéria usando análise multicritério em um ambiente GIS para criar um mapa de suscetibilidade e risco de inundação para a detecção e previsão de locais propensos a inundações. Fatores ambientais e antropogênicos, como características hidrológicas, geomorfológicas, geológicos, tipo de solo e uso e ocupação da terra, bem como pontos de ocorrência de inundações, foram coletados de diferentes bancos de dados para essa análise. A partir dos resultados, as quatro principais categorias de nível de risco de inundação são baixo, médio, alto e muito alto, representando 13,04, 31,29, 36,42, 19,25% da área total de Abeokuta South e 11,48, 22,73, 35,06, 30,73% da área total de Lekki, respectivamente. O uso e a cobertura do solo, bem como a distância da rede de drenagem, são os principais determinantes do fenômeno de inundação em ambas as áreas. Embora a elevação não desempenhe um papel importante na distribuição dos níveis de risco em Lekki, ela desempenha no caso da cidade de Abeokuta South, uma vez que algumas áreas próximas à rede de drenagem tinham baixa suscetibilidade por estarem localizadas em altitudes elevadas. Como as inundações na Nigéria são um problema grave que requer a atenção de todas as partes interessadas com o objetivo de prevenir e resolver seus efeitos adversos que representam uma ameaça à sobrevivência humana, os resultados deste estudo servem como uma ferramenta fundamental de avaliação para o desenvolvimento sustentável pelas autoridades públicas com jurisdição territorial.
Floods are considered one of the most common threats to human life and properties. And assessment of vulnerability and susceptibility is the first step in the management of flood hazard. It is a vital step that can help policymakers identify and implement policies that will minimize the risk of flooding. This research aims to develop a methodology used to map two selected cities in South-western Nigeria that are vulnerable to flooding, using multi-criteria analysis under a GIS environment to create a flood susceptibility and risk map for the detection and forecasting of flood-prone locations. Environmental and anthropogenic factors such as hydrological, geomorphological, land use, and socio-economic characteristics, soil type and geological data as well as points of flood occurrences were collected from different databases for this analysis. From the results, the four main categories of flood risk level are low, medium, high, and very high representing 13.04, 31.29, 36.42, 19.25 % of the total area for Abeokuta South and 11.48, 22.73, 35.06, 30.73% of the total area of Lekki respectively. Land-use and Land cover as well as the distance from drainage network are the main determinants of the flooding phenomenon in both areas. While elevation does not play an important role in the distribution of risk levels in Lekki, it does for the city of Abeokuta South, as some areas close to the drainage network had low susceptibility because they were located at high altitudes. Because flooding in Nigeria is a severe problem needing the attention of all stake holders with a view to preventing and resolving its adverse effects that pose a threat to human survival, the results of this study serve as a fundamental tool for evaluation for sustainable development by public authorities with territorial jurisdiction.
Floods are considered one of the most common threats to human life and properties. And assessment of vulnerability and susceptibility is the first step in the management of flood hazard. It is a vital step that can help policymakers identify and implement policies that will minimize the risk of flooding. This research aims to develop a methodology used to map two selected cities in South-western Nigeria that are vulnerable to flooding, using multi-criteria analysis under a GIS environment to create a flood susceptibility and risk map for the detection and forecasting of flood-prone locations. Environmental and anthropogenic factors such as hydrological, geomorphological, land use, and socio-economic characteristics, soil type and geological data as well as points of flood occurrences were collected from different databases for this analysis. From the results, the four main categories of flood risk level are low, medium, high, and very high representing 13.04, 31.29, 36.42, 19.25 % of the total area for Abeokuta South and 11.48, 22.73, 35.06, 30.73% of the total area of Lekki respectively. Land-use and Land cover as well as the distance from drainage network are the main determinants of the flooding phenomenon in both areas. While elevation does not play an important role in the distribution of risk levels in Lekki, it does for the city of Abeokuta South, as some areas close to the drainage network had low susceptibility because they were located at high altitudes. Because flooding in Nigeria is a severe problem needing the attention of all stake holders with a view to preventing and resolving its adverse effects that pose a threat to human survival, the results of this study serve as a fundamental tool for evaluation for sustainable development by public authorities with territorial jurisdiction.
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Palavras-chave
Flood, G.I.S, Multicriteria Analysis, Abeokuta, Lekki, Nigeria, Inundação, Mapeamento, Análise Multicritério