On a construction project, engineers forecast the stresses the project will undergo over its lifespan. These estimates are usually conservative in nature and work under normal circumstances. But, with rapid changes in climate, it is difficult to predict what the future will hold, and therefore, estimates need to be a little more than conservative. That is what engineers did while constructing the new levee system in New Orleans and that might have just saved residents from Hurricane Ida, Time reported.
Hurricane Ida has badly affected the North-East in the US; 45 lives were reported to be lost across six states, with New York City reporting 3.15 inches (8 cm) of rainfall in just one hour, BBC reported. Hundreds of people had to be evacuated from flood basements, underground transit systems, and flooded streets. The rapid intensification of the storm also prevented New Orleans from carrying out mandatory evacuations. However, the city, which was badly affected by Hurricane Katrina in 2005, has not reported any casualties so far and the overestimations done by engineers during the construction of the new levee system might have contributed to this.
According to a Time report, the US Army Corps of Engineers was tasked with building the city's flood defenses which included pumps, dikes, and floodwalls. As with most of the construction projects, this multi-billion dollar project was designed to withstand rare, once-in-a-lifetime events. This is estimated by studying historic data and statistically calculating the probability of an event, like a hurricane in their case, occurring again.
However, given the changing climate, the engineers on the project realized that the models would not hold well for very long. Studies have suggested that these rare events could even end up becoming annual events. So, they decided to stretch their models and the contributing factors to design a system that would withstand extreme events.
Aware of the fact that lawmakers would not allocate resources to building defensive structures until another calamity struck and claimed more lives, the team overestimated the risks and factored in certain variables twice to ensure the system offered protection even in the worst of situations. The resultant systems held their ground while cities in the North-East were flooded.
As President Biden looks at making "historic investments" to Build Back Better systems, maybe using the Dutch model of a 'once in 10,000 years' event would help.