Resiliency of Cities – Damage Incurred by Sinkholes
Every year sinkholes appear all over the world from the USA to the Netherlands, either through natural occurrences or man-made influences. The sudden appearance of sinkholes can be quite frightening for people because the earth suddenly just disappears. These sinkholes are a serious hazard to society. It endangers human lives and causes damage to property and critical infrastructure which results, among others, in congestions on the roads. The most common picture people have of sinkholes are those that happen on the roads, but sinkholes can also appear under buildings like the sinkhole in Guatemala City.
On 25 May 2016 an underground water pipe burst in Florence, Italy, creating a 200-yard-long sinkhole that buried dozens of cars in the early hours of Wednesday. The sidewalk collapsed on the Lungarno Torrigiani, a road alongside the Arno River that is not far from the famous Ponte Vecchio, part of the city’s historic center, a Unesco World Heritage site.
In 2016, an enormous sinkhole appeared overnight due to human activity in Japan (Fukuoka), causing quite a fright. The sinkhole was quickly repaired – however, a few weeks later it appeared that the road was sinking again. This shows that, of course, it is better to focus on preventing sinkholes rather than on fixing them afterwards. The Netherlands, too, has been affected by sinkholes. In Leiden, a water pipeline broke, causing a car on the road to sink through the surface.
The phenomenon has a variety of different underlying causes, from water erosion to earthquakes, all which damage the foundation under the surface. A sinkhole appears when the foundation under the surface is eroded to the point that the structure can no longer support the surface and collapses, opening up a hole. It swallows roads, houses, office buildings, electricity lines and trees. One of the main causes behind the erosion of the foundation is water. The origin of this water can come from different sources. The water can either come from natural occurrences like the rain or flooding from a storm, but it can also come from leaking or broken waterlines under the ground. These leaking waterpipes and the deteriorated sewage system under the ground were also, to some extent, the causes behind the sinkhole in Guatemala City which swallowed a three-storey building. The waterline system under the ground had been neglected for a long time, which created the ‘right’ conditions for a sinkhole. This illustrates how crucial it is that the underground infrastructure is up to date and made resilient, in order to prevent sinkholes – brought about by human activity – from occurring. Especially areas with lot of heavy traffic are at a high risk – you definitely do not want a deep hole to appear in the middle of a highly populated city.
The sinkholes that appear cause damage to human life and property. Indirectly the economy is also affected in several ways, if a sinkhole appears on the road, as this leads to the disruption of the transportation of goods. This in turn results in companies losing precious time and money. It also prevents people from coming to work, which once again leads to a loss of income for people and the employers they work for. It is especially important that the cities are resilient against this phenomenon, due to the high population density in these areas.