Cities find green ways to scale back storm floods

Cities find green ways to scale back storm floods

For quite a century, New Orleans has trusted canals and pumps to urge obviate stormwater during a city where about half the land is below water level .

Now the bustling Mississippi port that expanded by filling in wetlands is spending $270 million to make spaces for rainwater, like the water garden planned on a 25-acre site provided by nuns who lived there before Hurricane Katrina.

The city is additionally installing underground holding tanks, porous pavement and other measures to scale back storm flooding and stress on huge pumps inbuilt the 1910s.

"We've got a scenario for everything," said Mary Kincaid, the city's chief resilience officer.

Tropical storms can dump amazing amounts of rain, and hurricane season starts June 1. But smaller storms also can overwhelm storm drainage.

So cities round the country are taking creative steps to tame stormwater as global climate change increases the amount and intensity of hurricanes and other storms. Rising sea levels also elevate groundwater levels in coastal communities, reducing the soil's ability to soak up rain.

"Stormwater runoff is one among the fastest growing sources of pollution," the federal Environmental Protection Agency states on its website. "When rain hits rooftops, parking lots and roads rather than wetlands, forests and grasslands, it tends to run into storm drains that are directly connected to our waterways."

In Pittsburgh, as in about 850 other areas where storm drains tie into sewer lines, sewage sometimes backs up into basements, floods streets and pours into rivers.

To attack one neighborhood's problem, the Pittsburgh Water & Sewer Authority installed underground tanks and planted grasses and other native plants near a hilltop as a water-absorbent "bioswale."

In New Orleans , where the very best neighborhoods reach 10 to 11 feet (3 to three .3 meters) above water level , Kincaid said, "We want to place in storage within the higher ground areas." The aim is to capture the rain before it can reach lower ground and pool up.

One such project is simply off Bayou St. John and down the road from Parkway Bakery and Tavern, where owner Jay Nix switched his parking zone from concrete to far more expensive permeable pavement. That has noticeably lowered flooding within the restaurant, said Nix, who once had to use big plastic bags of "fish fry" breading as sandbags. He has high hopes for the city's project, which features an underground tank and rain gardens.

"I think it's getting to work. it's to figure ," he said.

Other techniques include planting trees and digging lagoons in wide roadway medians. Jurisdictions like Portland, Oregon, require greenery-covered "ecoroofs" on some buildings.

Earlier, Portland bought 60 houses over 15 years, then turned a frequently flooded neighborhood into Foster Floodplain Natural Area. The work, including creek restoration for migrating salmon and steelhead trout, increased the flood storage capacity six-fold - enough to fill nearly 70 Olympic-sized swimming pools.

Since the 63-acre park's completion in 2012, an adjoining highway that flooded annually has flooded just one occasion , officials said. And quite 600 nearby homes and businesses north of the highway are also seeing less flooding.

Nearly all money for brand spanking new Orleans' projects comes from the US Department of Housing and concrete Development and therefore the Federal Emergency Management Agency, so Kincaid said they are not suffering from new coronavirus-related budget holes.

The city won a $141 million HUD grant in 2016 to form New Orleans' Gentilly neighborhood a "resilience district."

The centerpiece are going to be an enormous water garden where the Congregation of St. Joseph's convent was destroyed by Katrina flooding in 2005 and a later fire. The nuns are leasing the land to the town for $1 a year as long as it's used for water management and environmental education.

"We wanted to try to to something that would benefit the longer term which addressed an instantaneous need," said Sister Joan Laplace, 79, who lived at the convent on and off since 1960.

Atlanta's $90 million in current and planned "green infrastructure" projects have included replacing quite four miles of neighborhood streets with porous pavers and adding 32 stormwater planters alongside.

Since Hurricane Irma toppled trees in 2017, Miami has moved faraway from planting palms and has planted nearly 4,700 live oaks and other trees that take up more water and supply shade.

Miami expects to end updating its long-term stormwater management plan next year, said Jane Gilbert, the city's chief resilience officer.

Florida, once a reef , is now "one big porous limestone bed," Gilbert said. "As the ocean level rises, so do our groundwater levels," reducing drainage.

"We need to check out as some ways as possible of absorbing, containing, slowing the flow of water," she said.

When Hurricane Katrina broke New Orleans' levees and killed quite 1,400 people, that raised global awareness of the bounds of flood protection by dikes and pumping stations, said Stephane Hallegatte, a lead economist with the planet Bank's Global Facility for Disaster Reduction and Recovery.

"We need protection which may fail gracefully," he said. "The advantage to a nature-based system is that they tend to not fail in catastrophic fashion."