If you’re from Delaware, it’s likely that you, or someone you know, experiences flooding, as surveys have shown that 48% of Delawareans experience flooding at least once a year. This greatly impacts Delaware’s communities, as was seen when the remnants of Hurricane Ida caused record flooding that lifted cars, covered bridges, and caused residents of Wilmington to evacuate their homes. As our climate changes, we are likely to see higher sea levels and more frequent and intense storms and it may feel like flooding is unavoidable. However, with good planning, it is possible to use green infrastructure to mitigate this issue.
Green infrastructure comes in many forms and serves many purposes in our communities. In most contexts, green infrastructure refers to water management practices that help mimic parts of the water cycle that are disrupted in urban and suburban areas. It focuses on absorbing water where it lands, rather than using gray infrastructure – gutters, pipes, concrete, etc. – to move water away from where it lands to local waterways.
The Clean Water for Delaware Act, HB 200, emphasizes the importance of prioritizing projects that use green infrastructure. Several communities throughout the state have already begun working on projects that use green infrastructure to help improve water management. To help get a better idea of the different types of green infrastructure in general and throughout the state, we are going to walk through some projects below.
Wilmington’s Southbridge neighborhood has long struggled with flooding that has been increasing in intensity over the years. In this neighborhood, because of Combined Sewer Overflows, stormwater and sewage were two areas that need to be addressed simultaneously. Community advocates and local planners decided that in order to address the concerns, they could design a wetland park to mimic the natural benefits of our wetlands in Delaware. After years of advocacy, construction began in 2019. Wetlands are incredibly productive and important ecosystems that filter water, help prevent erosion and flooding, provide habitat for native plants and animals, absorb stormwater, and create spaces for recreation and leisure. The Southbridge Wilmington Wetland Park addresses stormwater flooding by channeling stormwater from the neighborhood directly into the newly restored wetlands where it then has a chance to filter and absorb into the ground like the natural wetlands we have throughout the state. Wetland parks are incredible examples of green infrastructure that help keep stormwater out of neighborhoods and back into nature.
Coastal flooding is a major concern in southern Delaware and many have taken initiative to combat it with permeable pavement. Regular pavement blocks the absorption of water into the soil below it which then contributes to flooding. Permeable pavement allows water to soak through and then relies on one of two pathways for stormwater: Underground reservoirs or absorption into soil and the water table below. Both pathways help reconnect stormwater with the natural water cycle and can help make communities more resilient against sea level rise and more frequent flooding.
Rain gardens are a common form of green infrastructure. They are integrated into landscaping and address stormwater management by reducing runoff and absorbing stormwater. These gardens often serve as the first line of defense against flooding and capture rainwater as it falls which slows its path to flooding into roads and streams. They also help filter the runoff as it travels towards the streams which in turn helps clean the water that we eventually drink. In addition to addressing runoff, rain gardens support local pollinators and native species while adding color and beauty to the communities they are built in.
Like rain gardens, green roofs are also a fairly common form of green infrastructure. Also referred to as ‘rooftop gardens,’ green roofs are a thin vegetative layer grown on rooftops. They have numerous benefits, including natural insulation to reduce the need for heating and cooling, and they help absorb stormwater reducing the flow of rainwater or snowmelt into gutters and drains. For some buildings, it even provides a space for leisure and recreation in urban areas where there is limited access to green spaces.
Urban Tree Canopy
Sometimes the best way to address environmental issues is to replace what was lost. Investing in urban tree canopy cover is an increasingly popular way to address many environmental concerns including heat islands, air pollution, and soil erosion. Trees’ natural processes and root systems absorb and store stormwater, create shade, provide habitat, and help to filter air and capture carbon dioxide in our atmosphere.
Delaware’s gray infrastructure is aging and the systems we currently rely on, such as gutters, pipes, and tunnels, have a limited capacity. There is no surprise that when addressing climate change, one of the biggest challenges we face is how to manage water for drinking, recreation, and healthy ecosystems. It is critical that community advocates continue to push for investment in green infrastructure, such as the examples above, to increase Delaware’s resiliency to climate change and stormwater flooding. If you are interested in learning more about different types of green infrastructure, visit this page by the Environmental Protection Agency.
Marissa McClenton is the author of this blog and a student at University of Delaware as well as the Clean Water Campaign’s Grassroots Organizer. Stay tuned for more insights and resources from the DEIJ Corner and Marissa in the future!