Making cities 'spongy' could help fight flooding — by steering the water underground

After being hit by two natural disasters in one year, cities, Indigenous tribes, and government agencies in Whatcom County on the Nooksack River are working together to create a new plan to deal with flood risk and salmon restoration. The Floodplain Integrated Planning team is overcoming distrust among its partners to build a more holistic plan that incorporates tested solutions like fish-friendly floodgates, levee repairs, and property buyouts to remove homes that will continue to be flooded in the future.

After experiencing extreme flooding, Hoboken, New Jersey, has reduced its flood risk by rebuilding its sewers to add capacity and designing new infrastructure, like parks, to collect and redirect storm water.

The design firm Arup calculates cities' ability to retain water through nature and helps them implement other solutions to flooding, like building rain gardens or public messaging strategies, depending on individual needs.

Following the 2025 Texas Hill Country flood that killed 139 people, state lawmakers passed four bills and allocated $74 million to expand flood-warning infrastructure across 30 counties; when historic flooding struck the same region a year later, only three people died.

In response to recurring glacial flooding outbursts, Juneau has implemented an early warning dashboard, $8 million temporary flood barriers, and ongoing scientific research. The solutions are too new to demonstrate measurable flood damage reduction, but increased community participation in preparedness activities is one promising impact.

Coastal communities in Maine are building living shorelines to adapt to sea level rise and address erosion concerns. This nature-based solution uses native plants and materials, or even discarded holiday trees, to bolster shorelines against strong storms and higher tides. And they get stronger as nature takes its course over time.

Resiliency parks in Hoboken, New Jersey, look like typical playgrounds and basketball courts. Unlike the average park, they have discrete drains and sit on top of underground tanks that prevent flooding by holding millions of gallons of rainwater.

Stormwater fees, which are based on property runoff, are funding infrastructure upgrades and green spaces to absorb rainwater, reduce damage from flooding and improve water quality. Several municipalities have seen reduced flood damage and increased water quality after implementing stormwater fees, and have even hosted community events to educate residents on how the fees are used to make improvements.

One of China’s many “sponge cities,” Haikou, experiences virtually no flooding after transitioning to primarily green, nature-based infrastructure instead of gray infrastructure like concrete and flood barriers. Prioritizing things like parks, wetlands, mangroves, and permeable pavement allows the city’s ground to soak up more rain.

The city of Amsterdam funded a blue-green roofs program to reduce both flooding and the urban heat island effect. The water collection system stores and releases rainwater, the variety of indigenous plants increase biodiversity, and the connected digital network allows them all to be controlled remotely.