A collective and grassroots approach to “green” infrastructure, at least in major cities and their development plans. The goal of Cop26, the conference organized by the UN in Glasgow, is to find common solutions to fight climate change. The construction industry can also take part in testing new and innovative development models, which must support both the goal of industrial decarbonisation and the ambition to create increasingly sustainable infrastructure.
City administrations are being called on to do their part in responding in the short term to increasingly devastating and unmanageable weather events, to prevent them from turning into a nightmare that blocks economic development and hinders the well-being of entire communities.
New Orleans is an example of how authorities can adapt, in a city that is a symbol of the battle against climate change and that in recent months has been developing a collective response.
From the construction of buildings to the structure of parking lots, from the positioning of parks to the characteristics of crosswalks, everything is conceived and designed to mitigate the harmful effects of hurricanes but also of rainfall.
New Orleans, a wounded city resurrected by green infrastructure
New Orleans, now a universal symbol of the dramatic impact of climate events, has learned a lesson from Hurricane Katrina, which swept through the city in 2005, leaving behind 1,800 dead and wreaking $125 billion (€107 billion) in damage.
The city’s resurrection depends in part on “green” infrastructure, the only possible barrier to the devastating effects of torrential rains, floods and hurricanes. In fact, the recent study “The Benefits of Community-Driven Green Infrastructure,” carried out by a number of city organisations including Water Wise Gulf South and Healthy Community Services, has calculated that “every dollar invested in green infrastructure projects in New Orleans ensures a six-fold return in terms of economic, social and environmental benefits.”
The ratio of one to six demonstrates the advantages of this new community approach to infrastructure, ranging from wastewater management to city river control to rainwater harvesting. Techniques like these will be the focus of discussions at Cop26, the United Nations Climate Change Conference, in Glasgow from 31 October to 12 November.
Green infrastructure to make the city’s neighbourhoods safe
The neighborhoods of Tremé to the 7th Ward to the Upper 9th Ward suffer are where much of New Orleans’ African-American community lives, and suffer from regular flooding. Calls received by 311, the city’s number for reporting water-related problems, have increased over the past five years by 46%. The report on the benefits of green infrastructure in the city highlights how — apart from the most devastating hurricanes — the small floods resulting almost daily from less severe weather events also affect the daily lives of residents and are a drain on the city’s finances.
Hence the report documents the projects — partly under construction and partly to be planned in the short term — that could make these areas in one of the most beautiful cities in the United States much safer. For example, anti-rain barriers to protect the foundations of buildings; of special flooring capable of draining excess water; and, of course, of water management systems capable of collecting water and conveying it into a network of underground pipes without causing the city’s waterways to explode.
According to the report, the projects now underway in these city areas will be able to manage and retain 6.5 million gallons of water in the short term, while increasing green space by 45 acres (18 hectares). A good start, but not enough to make the entire city safe from the hurricanes on the Gulf of Mexico that batter the southern coast every year from late August to early September.
Protecting the environment, house by house
New Orleans is a case study for an innovative community model of investing in “green” infrastructure. To date — thanks in part to the absence of large state and federal appropriations — the city’s various neighborhoods are moving independently, each with its own projects and customised solution to minimise the negative impacts of weather events.
The Gentilly Resilience District, for example, includes seven projects that focus on the redevelopment of different areas and the creation of water networks, especially within the parks, useful to divert the course of excess water. Another project started by residents undertook works in Duncan Plaza, Armstrong Park, as well as the extension of the Lafitte Greenway. These interventions will create “streetside rain gardens” to drain all the excess water, and porous parking lanes. Overall, the entire project will reduce flooding in the area by 39%.