The Homo Scientificus blog looks at the ways Science and Culture shapes everyday life.
For years urban flooding has become an increasingly relevant problem that needs to be addressed. Besides climate change, one of the biggest reasons behind urban flooding is the presence of impervious surfaces. Non-porous concrete, paving, asphalt, brick, and stone are all classified as impervious surfaces. These materials are commonly used in the construction of roads, pavements, and parking lots. In towns and cities, flash flooding and urban flooding are becoming more common due to this. These surfaces are causing damage to the environment and people’s lives.
The ever-expanding presence of large areas made up of non-porous materials inundates cities and towns’ stormwater systems. Essentially these downpours cannot escape into the earth, and with stormwater drainage systems often at capacity during heavy floods, the water remains on the surface. The issue of abundant impervious surface areas is often exasperated in developing countries. These countries face stormwater planning issues and degenerating drainage systems that cannot keep up with heavy rains.
A report by Christophe Le Jalle, Gilles Burkhardt, and Denis Desille addresses the many issues surrounding stormwater systems in developing countries. Their findings highlight the challenges developing countries face with urban flooding. However, it is essential to note that impervious surfaces compound stormwater drainage system problems in developing and developed countries. When impervious surfaces frequently prohibit rainwater from being absorbed into the earth, large-scale urban flooding occurs and ravages cities and towns. Unsurprisingly because of this, urban flooding is classified as a natural disaster.
Moreover, according to a 2019 scientific report, approximately 54% of the world’s population inhabits urban areas. This figure is expected to increase to an astonishing 66% by 2050 with the current urban expansion rate and world population growth figures. With more people moving to densely populated urban areas, there is a greater need for infrastructures like roads, airports, and buildings. Most of the new infrastructure required is likely to be developed with impervious materials, thus creating more and more impervious surfaces and more environmental and economic challenges.
Besides stormwater issues, there are other longstanding effects associated with urban flooding caused by impervious surfaces. Firstly, when urban flooding occurs, and water sits atop these surfaces, infrastructure is damaged. Additionally, water moves across the landscape, carrying many pollutants and biological contaminants from cities into waterways. This is a devastating problem as wildlife and fish are poisoned and exposed to harmful substances. Humans are also affected by the pollutants and dangers of stagnating floodwaters.
Although stormwater drains play a crucial and necessary role in taking floodwater from urban areas into the nearest large body of water like lakes and oceans, they also contribute to environmental and human health problems. A study featured in Science Direct supports the theory that the effects of urban flooding can be prevented with proper flood mitigation planning, and stormwater drainage is a part of this planning. However, when water is drained from urban areas where the water cannot soak into the land, many pollutants like hazardous fertilizers travel into waterways. This creates dead zones in the ocean and the occurrence of dangerous red tides.
Fortunately, much can be done to combat the adverse environmental, economic, and health problems that arise due to harmful impervious surfaces that cause urban flooding. Some of the proposed solutions are the implementation of green roofs and the introduction of porous concrete and asphalt in building and roadway construction. Others have rallied behind rain gardens and better urban planning as solutions to urban flooding in areas with high volumes of impervious surfaces.
Ultimately if porous materials are utilized in the construction of roads, buildings, parking lots, pavements, and airports, urban flooding would not be as frequent. Additionally, with a significant decrease or elimination of impervious surfaces in urban areas, urban flooding will not prove to be as hazardous to the environment, economy, infrastructure, and human life.
WORDS: Jason Collins.