Urban flooding is on the rise due to climate change and increasing urbanization. However, not all city blocks are equally safe. Researchers studied how the layout of buildings and structures contributes to the safety of pedestrians during flooding. The team’s simulated results led to the recommendation of modifying building corners and protective block layouts to reduce pedestrian risk.floods are becoming more frequent and severe due to climate change and increased urbanization. In a study published in the journal Physics of Fluids, researchers from Beijing Normal University, Beijing Hydrological Center, and the China Institute of Water Resources and Hydropower Research examined how the design of city blocks can impact pedestrian safety during flooding.
According to author Zhong-Fan Zhu, climate change is causing more extreme precipitation events in terms of both frequency and intensity. Additionally, rapid urbanization is changing the hydrological cycle.The researchers examined the physical properties of the surface below in urban areas. This includes the transformation of previous forestland, wetland, and agricultural land into impervious urban lands, leading to more frequent urban flood events.”
In their study, the researchers determined the flood conditions that put pedestrians at risk and used computer simulations to evaluate city block patterns, building heights, and street widths in order to find the best configurations for protecting people.
Every city has its own distinct buildings and building layouts. The team conducted simulations for three different urban block designs, including buildings located in close proximity to each other.
Buildings are neatly arranged and evenly spaced in columns and rows, while others are offset and staggered. There is a square area that is tightly outlined by buildings, with just four buildings enclosed within.
When buildings are arranged in a line, such as in the grid and enclosed layout, they create a safety zone by blocking some of the water and wind. However, the staggered approach lacks this protection and has more danger zones due to increased water and wind circulation.
Changing the shape of the buildings can also protect pedestrians. Rounding or adding recesses to building corners can significantly reduce areas of dangerously high floodwater and windspeed. However, this intervention may not be as effective in all cases.
Wind also had an impact on the safety zone, albeit to a lesser extent.
The role of wind in safety was complex and crucial.
According to Zhu, “In certain situations, floodwater alone may not cause instability for pedestrians, but the addition of wind force could create a hazardous scenario. However, in other cases, wind may actually contribute to maintaining pedestrian stability and protecting against floodwater. It appears that wind acts as a ‘double-edged sword’.”
Varying building heights can help to alleviate the adverse effects of wind.
When planning urban expansion, cities should consider utilizing enclosed block arrangements and constructing buildings with.
To explore the potential impact of wind and floodwater on pedestrians, researchers suggest using rounded or circular footprints and seeking input from a physicist.