Urban centers are more prone to flooding than other areas because streets, parking spaces and buildings are impenetrable, meaning water cannot penetrate the ground in a forest or meadow. Instead, it flows.
Detroit, like many large cities, deals with running rainwater by connecting it to sewers. The mixture is then poured into the treatment plant. During a recent storm, electrical interruptions and mechanical problems knocked out four of the 12 pumps at two large pump stations.
The agency has spent million 10 million over the past several years to upgrade these two pump stations alone, and has spent millions more on other improvements. But to modernize the sewer system completely, it is necessary to build a separate storm water network at a cost of more than 17 17 billion.
Mikhail Chester, an infrastructure and policy researcher at Arizona State University, says stormwater infrastructure is aging across the country, and many governments are resorting to band-aid solutions rather than creating more resilient systems. Chester adds and mechanical and electrical systems will occasionally fail during major hurricanes.
However, even if the pump stations had worked perfectly, they would not have been able to prevent the catastrophic floods.
Detroit’s pumping stations, which are very similar to stormwater infrastructure, are designed to keep up with 10-year storms, meaning the amount of rain within an hour, which is one in 10 likely to happen in any year. The 10-year-old storm in the Detroit area will receive about 1.7 inches of rain in an hour, according to data from the National Weather Service.
During the June storm, intense rainfall was observed in some parts of Detroit, which, according to water-authority, would be characteristic of hurricanes (more than 7.7 inches of rain per hour) exceeding the capacity of the pumping stations.
But rainfall forecasts are based on historical data that may not represent true barriers to major storms, according to Ann Jefferson, a hydrologist at Kent State University. Hurricanes that are expected to be 10 in a given year will now occur more frequently due to climate change. And she says few agencies are considering climate change in their structural formations.
Jefferson says, “We are locating ourselves in the environment of the past.
Governments hoping to take climate change into account when designing infrastructure face uncertainty – will they plan for a better emission outlook or worse? And it’s hard to predict exactly how rain will affect performance.
Planning a major hurricane is an admirable goal, but it is also costly. Chester says larger pumps and pipes are more expensive to build and more difficult to install. And the price increase is not linear, he added – double-capacity pumps or pipes will in most cases be more than double the price.
Coastal cities face dire weather risks and some invest aggressively to prevent it. According to the Tampa Bay Times, Florida’s Tampa has upgraded સ્ટે 27 million worth of pump stations and other infrastructure after major floods in 2015 and 2016. Some upgrades seem to be working – at least this year, the city avoided flooding during major hurricanes like Hurricane Elsa.
However, the rising sea off the coast of Tampa could soon cover the pump outlets. If the sea level reaches a point where water is to flow out of the storm pipes, the system will not be able to draw water from the city.
Some cities want to install other facilities, such as storm ponds and rain gardens, to help manage urban flooding. Jefferson says grassy areas like rain gardens can reduce excess water volume and speed. If it has enough facilities built in the right places, it can help prevent small floods, but she says, but like other hurricane infrastructure, they are not usually designed to prevent flooding during large hurricanes.