A fine-scale spatial analytics of the assessment and mapping of buildings and population at different risk levels of urban flood

Nowadays, urban flooding is becoming a severe issue in most of the developing and developed countries. The growth of the urbanization rate is also increasing, and the United Nations (UN) projected that 68 % of the world’s population would live in urban areas by 2050. People tend to migrate from rural to urban areas, which expose them more vulnerable to urban floods. The flood-related damages and deaths are increasing every year globally. Using the Birmingham city, Alabama (AL), USA as the study area, the objective of this research is to assess potential damage risks due to flood exposure of buildings and population in an urban area. Different social and environmental factors influence urban floods in an urban area. This paper considered elevation, slope, flow accumulation, land-use, soil types, and distance from the river as significant influential factors to urban flooding. The flood risk model hence can be developed by using an integrated GIS and cartrographic approach, in which we assessed and assigned weights to these factors and formed a GIS risk assessment model, which shows the level of flood risks in the floodplain areas of Birmingham and quantifies and maps both commercial buildings, home buildings, and populations’ exposed to flooding risks. This study found that the Valley Creek area is the highest flood risk zone in Birmingham, and about 48.85 percent of Valley Creek’s floodplain area will face very high flood risk. The findings further reveal that total number of 5602 people are living in high and very high flood risk zones in Birmingham that approximates 44.04 % of the total population in this floodplain area. The physical vulnerability is also assessed, and findings suggest that the Valley Creek zone has the highest percentage of residential (i.e., 56.14 %) and commercial (i.e., 75.34 %) buildings located in very high flood risk areas. Our study providing a GIS risk assessment approach to locating and mapping the areas, buildings, and populations from the most to the least at risks with a fine spatical scale for urban flood risk management. The numbers of vulnerable buildings and populations within each risk category are quantified and their distributions are mapped. Therefore, revealing population’s and buildings’ risks and their geographic information, this flood risk assessment can help local governments and communities prepare better to take actions against future urban flood events in Birmingham, and this integrated GIS and cartographic analysis for fine flooding assessments can be applied to other urban areas for flood mitigation and risk management.