Green Infrastructure

To address these risk factors, the city has initiated the implementation of numerous projects centered around green infrastructure, primarily targeting the reduction of flooding. Green infrastructure refers to an approach that uses natural systems and processes to manage water, conserve resources, and provide multiple environmental benefits.

It involves strategically incorporating natural elements into urban planning and design to mimic the functions of natural ecosystems and enhance the sustainability of built environments. In addition, these projects integrate gray infrastructure, such as drainage pipes and canals, into the design, ensuring a comprehensive approach to stormwater management.  

Green infrastructure when partnered with gray infrastructure improvements lessens the burden on the city’s drainage system by create a gray / green network of mitigation. 

Benefits of Green Infrastructure

Improved Stormwater Management: Green infrastructure reduces the volume and velocity of stormwater runoff, minimizing the strain on traditional drainage systems and reducing the risk of flooding.  

Enhanced Water Quality: Natural systems help filter and cleanse stormwater, removing pollutants and improving water quality in rivers, lakes, and other water bodies.  

Climate Change Adaptation: Green infrastructure contributes to climate change adaptation by mitigating the urban heat island effect, reducing energy consumption, and enhancing overall resilience to extreme weather events.  

Biodiversity and Habitat Preservation: By incorporating green spaces and restoring natural habitats, green infrastructure supports local biodiversity and provides habitats for plants and animals.  

Improved Health and Well-being: Access to green spaces has been linked to physical and mental health benefits, including reduced stress, improved air quality, and increased opportunities for physical activity and community interaction.  

There are various types of green infrastructure that exist, each serving different purposes in managing stormwater, enhancing environmental sustainability, and improving the overall resilience of urban areas.

Some common types of green infrastructure include:  

A rain garden is a key component of green infrastructure that helps manage stormwater runoff in a sustainable and environmentally friendly manner. It is a shallow depression or basin that is designed to collect rainwater from roofs, driveways, and other surfaces during rainfall events. The purpose of a rain garden is to allow the captured rainwater to slowly infiltrate into the soil rather than flowing directly into storm drains or water bodies. This helps reduce stormwater runoff, which can contribute to flooding and water pollution. Rain gardens are typically planted with a variety of native plants, grasses, and flowers that are tolerant of both wet and dry conditions. These plants have deep root systems that aid in absorbing and filtering the collected rainwater, promoting groundwater recharge and improving water quality.  

Benefits of rain gardens include:  

• Stormwater Management: Rain gardens help reduce the volume and velocity of stormwater runoff, decreasing the strain on drainage systems and mitigating the risk of flooding.  
• Water Quality Improvement: As the rainwater filters through the soil, pollutants and sediments are trapped and removed, resulting in improved water quality in nearby water bodies.  
• Groundwater Recharge: Rain gardens facilitate the recharge of groundwater by allowing rainwater to infiltrate into the soil, replenishing underground water sources.  
• Biodiversity and Habitat Creation: Native plants in rain gardens provide habitats for birds, butterflies, and other beneficial insects, promoting biodiversity in urban areas.  

• Aesthetics and Community Engagement: Rain gardens can enhance the visual appeal of landscapes and serve as educational tools, promoting awareness about sustainable stormwater management practices within the community.

Permeable pavement, also known as porous pavement, is a type of pavement surface that allows water to infiltrate through the pavement and into the underlying soil or a designed drainage system. Unlike traditional impervious surfaces like concrete or asphalt, permeable pavement is designed to manage stormwater runoff by promoting infiltration and reducing stormwater runoff volume.

There are several types of permeable pavement, including:  

• Permeable Interlocking Concrete Pavers: These are concrete pavers with gaps between them, allowing water to pass through the joints and infiltrate into the ground. 
• Permeable Concrete: Also known as pervious concrete, it is a mixture of coarse aggregate, cement, and minimal fines. The resulting porous structure enables water to infiltrate through the pavement.  
• Grid Systems: These are reinforced grid-like systems made of concrete or plastic materials. The void spaces within the grid are filled with gravel or grass, allowing water to flow through and infiltrate into the ground.  

Benefits of permeable pavement include:  

• Stormwater Management: Permeable pavement helps to reduce stormwater runoff volume by allowing rainwater to infiltrate into the ground, thereby mitigating the strain on drainage systems and reducing the risk of flooding.  
• Water Quality Improvement: The permeable nature of the pavement allows for natural filtration and treatment of stormwater, removing pollutants and improving water quality before it reaches groundwater or nearby water bodies.  
• Groundwater Recharge: By facilitating water infiltration, permeable pavement helps to replenish groundwater resources, maintaining a more sustainable water cycle.  
• Reduced Urban Heat Island Effect: Permeable pavement can help mitigate the urban heat island effect by reducing surface temperatures compared to traditional impervious surfaces, as water infiltration helps to dissipate heat.  
• Improved Safety and Durability: Permeable pavement reduces the accumulation of standing water, reducing the risk of hydroplaning and improving traction for pedestrians and vehicles. It also tends to have a longer lifespan and requires less maintenance compared to traditional pavement.  

A bioswale is a landscape feature designed to manage stormwater runoff and promote natural water filtration. It is a shallow, vegetated depression or channel that is strategically constructed to collect and direct stormwater runoff, allowing it to slowly infiltrate into the soil. Bioswales are typically planted with a variety of native plants, grasses, and shrubs that have deep root systems and are capable of withstanding both wet and dry conditions.

The vegetation helps to slow down the flow of stormwater, enhance infiltration, and improve water quality by capturing and filtering pollutants. A layer of engineered soil or organic material is often incorporated into the bioswale to enhance filtration and remove pollutants from the stormwater. In some cases, underdrains are installed at the bottom of the bioswale to facilitate excess water drainage during heavy rainfall events.  

Benefits of bioswales include:  

• Stormwater Management: Bioswales help to reduce stormwater runoff volume and flow rates, mitigating the risk of flooding and alleviating pressure on drainage systems.  

• Water Quality Improvement: The vegetation and filter media in bioswales trap sediment, nutrients, and other pollutants, preventing them from entering water bodies and improving overall water quality.  
• Groundwater Recharge: By promoting infiltration, bioswales contribute to replenishing groundwater reserves and maintaining a sustainable water cycle.  
• Biodiversity and Habitat Creation: Bioswales with diverse native vegetation provide habitats for birds, butterflies, and other beneficial insects, promoting urban biodiversity.  
• Aesthetics and Community Engagement: Well-designed and maintained bioswales enhance the visual appeal of landscapes, create green spaces within urban areas, and provide opportunities for community education and engagement.  

A detention basin, often referred to as a dry pond or dry detention basin, functions as a temporary storage facility for stormwater runoff. It is engineered to effectively manage stormwater by capturing it and gradually releasing it until fully drained. Unlike wet ponds, which retain permanent standing water, detention basins are specifically designed to mitigate flooding from heavy rainfall events by temporarily holding back runoff.

These basins are structured to slow down the flow of stormwater, allowing sedimentation of pollutants and reducing the speed of runoff, thus minimizing downstream flooding risks. Instead of maintaining a constant water level, detention basins are intended to either infiltrate water into the ground or discharge it to the gray infrastructure system within a predetermined timeframe, typically around 48 hours. Detention ponds may also be referred to as stormwater lots or bioretention areas.

Benefits of detention ponds include:

• Flood Control/Stormwater Management: Detention ponds help mitigate flooding by temporarily storing excess stormwater runoff during heavy rainfall events. By regulating the flow of water, they reduce the risk of downstream flooding, protecting communities and infrastructure.
• Water Quality Improvement: These ponds facilitate the settling of sediments and filtration of pollutants from stormwater runoff. As water is detained, suspended particles settle to the bottom, and contaminants are filtered out, leading to improved water quality in nearby streams, rivers, and other water bodies.
• Erosion Control: By slowing down the flow of stormwater, detention ponds help to prevent erosion of soil and sedimentation in water bodies downstream. This helps to maintain the stability of watercourses and preserve aquatic habitats.
• Aquatic Habitat Creation: Well-designed detention ponds can serve as habitats for various aquatic plants and animals. They provide opportunities for wildlife to thrive, contributing to biodiversity conservation in urban and suburban areas.
• Groundwater Recharge: Some detention ponds are designed to allow stormwater to infiltrate into the ground, replenishing groundwater resources. This helps to sustain local aquifers and maintain water availability in the surrounding area.
• Aesthetic and Recreational Value: Detention ponds can enhance the aesthetic appeal of neighborhoods and serve as green spaces for recreation and relaxation. When integrated with landscaping and walking paths, they provide opportunities for outdoor activities such as walking, jogging, and birdwatching.

Detention Chambers may also be used as a form of a detention pond.  Stormwater Detention chambers are large underground containers, that are designed to temporarily store runoff before slowly releasing it at a controlled rate into the gray infrastructure system. These chambers can often be found beneath parks, or parking lots.

Constructed wetlands are engineered systems that mimic the natural processes of wetlands to treat and manage wastewater or stormwater. They are designed to provide a cost-effective and sustainable approach for water treatment, ecological restoration, and habitat creation. Constructed wetlands consist of shallow basins or channels filled with various types of wetland vegetation, such as reeds, cattails, and rushes.

The wetland plants play a crucial role in the treatment process, as they help remove pollutants and nutrients through processes like uptake, adsorption, and microbial activity. Constructed wetlands play a significant role in stormwater management by providing effective and sustainable solutions to mitigate the impacts of stormwater runoff. 

Benefits of Constructed Wetlands include: 

• Stormwater Treatment: Constructed wetlands act as natural filters, removing pollutants and contaminants from stormwater runoff. As stormwater flows through the wetland, vegetation, soil, and microbial processes help trap and break down pollutants, including sediment, nutrients, heavy metals, and organic compounds. This treatment process improves the quality of stormwater before it is discharged into receiving water bodies or infiltrated into the ground. 
• Flood Control and Flow Reduction: Constructed wetlands help reduce the peak flow rates of stormwater runoff by temporarily storing and slowing down the flow. The vegetation and soil in the wetland act as natural sponges, absorbing and retaining excess water during heavy rain events. This attenuation effect reduces the risk of downstream flooding by providing additional storage capacity and allowing a controlled release of water over a longer period. 
• Ecological Benefits: Constructed wetlands provide habitat and support biodiversity. The presence of wetland vegetation, combined with the availability of water, creates a favorable environment for various plant and animal species. This promotes ecological balance, enhances wildlife habitat, and contributes to overall ecosystem health.  
• Aesthetics and Community Engagement: Constructed wetlands add aesthetic value to urban areas, providing green spaces that can be enjoyed by the community. They also offer opportunities for educational programs and community engagement, raising awareness about stormwater management, water conservation, and the importance of wetland ecosystems. 

Integrating green infrastructure elements such as bioswales, permeable pavement, and trees into street designs to manage stormwater, improve air quality, and enhance pedestrian safety.  

Due to its relatively low elevation compared to Lake Pontchartrain and the Mississippi River, New Orleans requires the implementation of gray infrastructure as a crucial component. Gray infrastructure encompasses the conventional or traditional built systems and structures that are specifically designed to handle water management, transportation, and other urban functions. Typically involving engineered solutions utilizing materials like concrete and steel, gray infrastructure is closely associated with centralized and highly engineered systems such as stormwater drainage networks, roads, and bridges. 

In New Orleans, gray infrastructure primarily refers to the city's extensive man-made drainage system. This encompasses catch basins, underground drainage pipes, large drainage canals, and pump stations. Gray infrastructure is essential for effectively removing accumulated rainfall from the city. Given the city's distinctive topography and the challenges posed by climate change, New Orleans adopts a hybrid approach, incorporating both gray and green infrastructure to address its water management needs. 

The integration of green and gray infrastructure, often referred to as a "hybrid" or "nature-based" approach, seeks to harness the benefits of both systems. This approach recognizes the importance of nature-based solutions in managing stormwater, improving water quality, reducing urban heat island effects, enhancing biodiversity, and promoting sustainable urban development. 

By combining the strengths of gray and green infrastructure, New Orleans can achieve a more holistic and resilient urban system that balance the needs of human populations with the preservation and restoration of natural environments.