Riverine Flooding

Extreme precipitation patterns from climate change lead to heavy rainfall events that cause rivers or creeks to overflow and flood the surrounding areas. Floods will increase in frequency and intensity, with areas that have not historically experienced flooding becoming increasingly exposed.

Potential Physical Interventions

Click on any strategy below for more detailed descriptions.

Urban Forest

Urban forests are planted tree communities of native or ecologically suited trees throughout cities that reduce urban heat and flooding risks, among other benefits.

Pervious Pavement

Pervious pavement are porous pavement materaisl that are designed to allow for slow percolation of storm runoff into the groundwater system.

Constructed Inland Wetlands

Constructing or restoring wetlands aims to recreate natural wetlands in an urban environment, which provides flood mitigation and water purification.

Increasing River Floodplain

Increasing riverine floodplains refers to restructuring river banks to their more natural form in order to mitigate flooding.

Rain Garden

Rain gardens are shallow to deep depressions filled with flood resistant, native plants that detain, slow, and filter stormwater runoff.

Creek Daylighting

Daylighting refers to removing obstructions from rivers, streams, and creeks to allow water to flow naturally, creating greater storage capacity during flooding events.

Stormwater Tree Pits

A stormwater tree pit is dug into the sidewalk adjacent to a street and a tree is planted to absorb and filter storm runoff and flooding.

Bioswale

Bioswales are long, depressed areas filled with flood resistant, native plants, rocks and layers of soil that decrease stormwater velocity and allow for groundwater infiltration and filtration

Retention/Detention Ponds

Retention or detention ponds are depressions at the end of a slope that retain and detain water depending on conditions, reducing flooding impacts.

Green Roofs

Green roofs are added green spaces, including plants, grasses, gardens, and potentially small farms, to the top or sides of buildings to decrease flooding and urban heat.

Examples

Calabazas Creek Flood Protection

Project to provide flood protection to 2,483 parcels in the Calabazas Creek watershed. A long detention basin next to the creek was built to capture high storm flows, preventing the creek from overtopping its banks in a 1% flood.

Valley Water repaired 14 severely eroding banks, using as little “hardscape” as possible. The project incorporated environmental stewardship principles to reduce erosion, with vegetation to enhance habitat for wildlife. Valley Water reduced the cost of the project by collaborating with the City of San José, which rebuilt a bicycle motocross (BMX) park at Calabazas Park.

California Academy of Sciences Living Roof

The Living Roof in San Francisco offers incredible insulation for the Academy of Sciences while simultaneously offering essential habitat for birds and insects and creating educational spaces.

Daylighting the Saw Mill River

Yonkers process of daylighting Saw Mill Creek has seen massively positive impacts on the physical landscape and the urban ecology.

San Francisco Urban Forestry Plan

The goals of the SF Urban Forest Plan is to plant 50,000 new trees by 2050, create a city wide street tree maintenance program, and to educate the public on the importance and brilliance of trees.

Coyote Valley Preservation

In November 2019, 937 acres in Coyote Valley were permanently protected through an innovative public and private partnership among Peninsula Open Space Trust (POST), Santa Clara Valley Open Space Authority (OSA) and the City of San José. The $93.46 million acquisition deal was funded in part by Measure T, a $650 million infrastructure bond approved by San José voters in November 2018

Smith River Plain Stream Restoration Plan

Restoration project that aims to improve and protect natural channel structure and function, water quality, floodplain connectivity, and biological resources along streams and waterways located in the Smith River Plain.

Moffett Park Specific Plan Urban Ecology

The Moffett Park Technical Plan lays out a city wide redevelopment of green infrastructure and Nature-Based Strategies that create habitats and natural corridors in order to reduce climate impacts and positively impact the community.

Seattle Urban Forest Plan

Seattle Urban Forestry plan implemented the planting of trees and understory plants, as well as public gardens with agriculture across the city. The increase of vegetation has reduced noise and air pollution, while reducing flooding across the city.

Napa River Flood Protection

The Napa River had a history of catastrophic flooding events, impacting downtown Napa, tourism, and agricultural assets. After a long history of utilizing engineered solutions, a multi-faceted collaboration with stakeholders, the Army Corps of Engineers, businesses, and others worked together to develop an approach to let the river run free - a "Living River" concept that was then and is still groundbreaking. The Napa Flood Protection project is an early and lasting example of using natural systems to manage flooding while protecting important assets in an affordable, durable, and effective way.

Tanner Springs Park

In the heart of Portland, a park has been renovated to include a detention pond that offers habitat to traveling birds, a community gathering place, and an effective mitigation effort against excessive rain and stormwater.

Street Edge Alternatives (SEA) Street Pilot

Seattle Public Utilities reconstructed an entire city street to include green infrastructure throughout. The infrastructure included bioswales, tree canopies, pervious pavement and more.

Cathedral Park Rain Garden

Portland's Biggest Rain Garden: Portland, Oregon has redeveloped their city to include a multitude of nature based solutions on large scales. One of their most successful implementations was developing 3,600 rain gardens throughout the city. Cathedral Park houses Portland's biggest rain garden.

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