GIS-Based Approach Applied to Study of Seasonal Rainfall Influence over Flood Vulnerability

Abstract

Flooding occurrence is one of the most common phenomena that impact urban areas, and this intensifies during heavy rainfall periods. Knowing the areas with the greatest vulnerability is of paramount importance as it allows mitigating actions to be implemented in order to minimize the generated impacts. In this context, this study aimed to use Geographic Information System (GIS) tools to identify the areas with greater flooding vulnerability in Espírito Santo state, Brazil. The study was based on the following methodological steps: (1) a Digital Elevation Model (DEM) acquisition and watersheds delimitation; (2) maximum and accumulated rainfall intensity calculations for the three studied periods using meteorological data; (3) a land use and occupation map reclassification regarding flood vulnerability and fuzzy logic application; (4) an application of Euclidean distance and fuzzy logic in hydrography and water mass vector variables; (5) a flood vulnerability model generation. Based on the found results, it was observed that the metropolitan and coastal regions presented as greater flood vulnerability areas during the dry season, as in these regions, almost all of the 9.18% of the state’s area was classified as highly vulnerable, while during rainy season, the most vulnerable areas were concentrated in Caparaó and in the coastal and immigration and metropolitan regions, as in these regions, almost all of the 12.72% of the state’s area was classified as highly vulnerable. In general, by annually distributing the rainfall rates, a greater flood vulnerability was observed in the metropolitan and coastal and immigration regions, as in these areas, almost all of the 7.72% of the state’s area was classified as highly vulnerable. According to the study, Espírito Santo state was mostly classified as a low (29.15%) and medium (28.06%) flood vulnerability area considering the annual period, while its metropolitan region has a very high flood vulnerability risk. Finally, GIS modeling is important to assist in decision making regarding public management and the employed methodology presents worldwide application potential.

Flood vulnerability analysis using the frequency ratio method with the watershed ecosystem in Bulukumba Regency, South Sulawesi Indonesia

“…Floods are affected by various characteristics of the climate system. It is mainly from rainfall patterns (intensity, duration, amount, time, phase-rain or snow) and also temperature patterns [9] which endangers the lives of living populations, especially in watercourses and their surroundings, as well as less marbled areas [10]. Flooding is also influenced by the conditions of drainage basins, such as the water level of rivers, snow and permafrost, soil characteristics (permeability, soil moisture, and its distribution), urbanization, and the presence of embankments, dams, and reservoirs.…”

“…Apart from these advantages, the problem of flooding is an obstacle and has a detrimental impact on the regional economy. Flooding occurs after heavy rains and causes damage mainly in urban areas [10,12]. Rural and urban drainage problems, weather anomalies, and forest land function experts becoming massive agricultural areas in the upstream area are factors in the occurrence of flood disasters in Bulukumba Regency.…”

Hydraulic Planning in Insular Urban Territories: The Case of Madeira Island—Ribeira Brava, Tabua

“…Just like droughts and hurricanes, for example, floods are classified as a natural and severe phenomenon. Nevertheless, they can be influenced by a region's characteristics, such as the soil type, the vegetation, and the weather [18,19]. Because of the huge impact that this phenomenon causes, in terms of natural devastation, economic and social losses, and, ultimately, human lives, floods are considered a "natural disaster" [19][20][21].…”

“…Nevertheless, they can be influenced by a region's characteristics, such as the soil type, the vegetation, and the weather [18,19]. Because of the huge impact that this phenomenon causes, in terms of natural devastation, economic and social losses, and, ultimately, human lives, floods are considered a "natural disaster" [19][20][21]. Flooding events often result from heavy rainfall, and their effects are mostly felt in urban locations that are disorderly occupied and located in hazardous areas.…”

“…Past civilizations looked to establish their cities in the surrounding areas of rivers because of their need for water. This need arose due to multiple purposes, including irrigation, animal necessity, and the assurance of more fertile land [19]. Therefore, one can conclude that urban areas are more prone to be affected by floods not only due to climate change but also as a consequence of an inadequately conducted urbanization process [19,24].…”