Green Stormwater Infrastructure – GSI – Preserve Our Planet

Green Stormwater Infrastructure, or GSI, are systems designed to manage stormwater using the landscape. Rain gardens, green roofs, permeable pavements, bioswales, and constructed wetlands are all examples of managing stormwater through the landscape.

In contrast to conventional “gray” infrastructure (such as storm drains and pipes) GSI mimics the natural water cycle by allowing stormwater to infiltrate into the ground, evaporate, or be used by plants, rather than running off into water bodies, which can lead to pollution and flooding.


Green Stormwater Infrastructure is Geared to Preserve Our Planet

We need more Green Stormwater Infrastructure Urgently

Urban development is rapidly encroaching on landscapes worldwide placing significant pressure on natural environments. Green Stormwater Infrastructure (GSI) helps preserve our planet by minimizing pollution in waterways through natural filtration, leading to healthier ecosystems.



Green Stormwater Infrastructure Key Elements

As mentioned above, there are a wide range of infrastructure elements that can control stormwater in natural settings. Some of these include the following.

Rain Gardens

Rain gardens are shallow, landscaped depressions designed to collect, absorb, and filter stormwater runoff from surfaces like roofs, driveways, sidewalks, and streets. They are typically planted with native shrubs, perennials, and flowers that help the water infiltrate into the ground, reducing the amount of runoff that flows into storm drains and waterways.

Key characteristics of rain gardens

  • Runoff Management: They capture and slow down runoff, allowing it to gradually seep into the soil, which reduces erosion, flooding, and pollution.
  • Water Filtration: The plants and soil in rain gardens filter out pollutants like chemicals, oil, and sediments from the water, improving its quality before it enters the groundwater or nearby streams.
  • Biodiversity: Rain gardens often use native plants, which support local wildlife and pollinators such as bees and butterflies.
  • Aesthetic Appeal: In addition to their environmental benefits, rain gardens can enhance the beauty of landscapes with vibrant plantings.
  • Rain gardens are a key feature of Green Stormwater Infrastructure, helping to create greener, more sustainable urban environments while reducing stormwater problems.
Green Stormwater Infrastructure | Improved Urban Environments
Green Stormwater Infrastructure | Improved Urban Environments

Green Roofs

Green roofs, also known as living roofs or vegetated roofs, are rooftops that are partially or fully covered with vegetation and a growing medium, planted over a waterproof membrane. They are designed to absorb rainwater, provide insulation, and create a habitat for wildlife, while also improving air quality and reducing urban heat.

  • Runoff Management: They capture and slow down runoff, allowing it to gradually seep into the soil, which reduces erosion, flooding, and pollution.
  • Water Filtration: The plants and soil in rain gardens filter out pollutants like chemicals, oil, and sediments from the water, improving its quality before it enters the groundwater or nearby streams.
  • Biodiversity: Rain gardens often use native plants, which support local wildlife and pollinators such as bees and butterflies.
  • Aesthetic Appeal: In addition to their environmental benefits, rain gardens can enhance the beauty of landscapes with vibrant plantings.
  • Rain gardens are a key feature of Green Stormwater Infrastructure, helping to create greener, more sustainable urban environments while reducing stormwater problems.

There are two main types of green roofs:

Extensive Green Roofs

  • Lightweight and shallow (2 to 6 inches of growing medium).
  • Require minimal maintenance.
  • Typically planted with drought-resistant, low-maintenance vegetation like grasses, sedums, and succulents.
  • Suitable for buildings that can’t support heavy loads.

Intensive Green Roofs

  • Deeper growing medium (6 inches or more), allowing for a wider variety of plants including shrubs and small trees.
  • Heavier and more complex, often designed as rooftop gardens.
  • Require more maintenance, including irrigation and fertilization.

Benefits of Green Roofs

  • Stormwater Management: Green roofs absorb and retain rainwater, reducing the amount of runoff that contributes to flooding and sewer overflow.
  • Energy Efficiency: The vegetation provides insulation, keeping buildings cooler in the summer and warmer in the winter, which lowers energy costs.
  • Urban Heat Island Effect: Green roofs help reduce the urban heat island effect by cooling the air and reducing the amount of heat absorbed by traditional roofs.
  • Air Quality Improvement: Plants on green roofs capture airborne pollutants and carbon dioxide, improving urban air quality.
  • Biodiversity: They provide habitat for birds, insects, and other wildlife, especially in densely populated urban areas.
  • Overall, green roofs are a key feature of sustainable urban design, helping cities become more resilient to climate change and environmental challenges.

Permeable Pavements

Permeable pavements are a type of surface designed to allow water to pass through it, helping to manage stormwater by reducing runoff and promoting groundwater recharge. Unlike traditional impermeable surfaces (like asphalt or concrete), permeable pavements are made of materials that allow rainwater and runoff to infiltrate into the underlying soil or be stored temporarily before slowly being absorbed.

There are several types of permeable pavements:

Permeable Concrete/Asphalt

These surfaces use a special mix with fewer fine particles, creating larger pores that allow water to pass through while still providing a solid, stable surface.

Pervious Pavers

These are individual units (such as bricks, stones, or concrete blocks) with gaps between them filled with permeable materials like gravel or sand, allowing water to infiltrate.

Plastic Grid Systems

A grid or lattice system is filled with gravel, soil, or grass to create a permeable surface, often used for driveways, parking lots, or pathways.

Benefits of Permeable Pavements

  • Stormwater Management: They allow rainwater to soak into the ground, reducing surface runoff, minimizing flooding, and decreasing pressure on stormwater systems.
  • Groundwater Recharge: By enabling water to infiltrate the ground, permeable pavements help replenish groundwater supplies.
  • Pollution Reduction: As water filters through the pavement and soil, pollutants such as oils, heavy metals, and sediments are naturally filtered out before reaching waterways.
  • Heat Island Mitigation: Some permeable materials (especially those planted with grass or ground cover) can help reduce surface temperatures and mitigate the urban heat island effect.
  • Erosion Control: By reducing the velocity and volume of runoff, permeable pavements help prevent soil erosion, especially in urban areas.
  • Permeable pavements are an important part of Green Stormwater Infrastructure, offering sustainable solutions for urban water management while contributing to more eco-friendly and resilient urban environments.

Bioswales

Bioswales are landscaped channels designed to capture, slow down, and filter stormwater runoff from surfaces such as roads, parking lots, and roofs. They use vegetation, soil, and sometimes engineered layers to treat and absorb rainwater before it flows into local water bodies or storm drains.

Key Features of Bioswales

  • Vegetation: They are planted with a variety of grasses, shrubs, and sometimes trees that help absorb water and filter out pollutants.
  • Sloped Design: Bioswales are typically shallow and sloped to guide water through the system, allowing it to slowly flow through the vegetation and soil for maximum filtration.
  • Engineered Soil Layers: Some bioswales include engineered layers beneath the surface to enhance infiltration and remove contaminants like sediments, oils, and heavy metals.
  • Permeable Bottom: The bottom of a bioswale allows water to percolate into the ground, replenishing groundwater supplies.
  • Benefits of Bioswales:
  • Stormwater Management: Bioswales help control and manage the flow of stormwater, reducing runoff, flooding, and erosion.
  • Pollutant Filtration: As water passes through the vegetation and soil, pollutants are filtered out, improving the quality of the water that eventually reaches rivers, lakes, or groundwater.
  • Groundwater Recharge: By allowing water to infiltrate the ground, bioswales contribute to groundwater replenishment, particularly important in urban areas with lots of impervious surfaces.
  • Aesthetic and Ecological Value: Bioswales add green spaces to urban environments, creating habitats for wildlife and contributing to the overall beauty and sustainability of the area.
  • Cost-Effective: Compared to traditional stormwater systems, bioswales can be more cost-effective because they reduce the need for expensive infrastructure, like storm drains and water treatment plants.
  • Bioswales are an essential component of Green Stormwater Infrastructure, helping cities manage rainwater more sustainably while enhancing the natural environment.
 Green Stormwater Infrastructure | Bioswales and Biobasins
Green Stormwater Infrastructure | Bioswales and Biobasins

Tree Canopy and Urban Forests

Tree canopy refers to the layer of leaves, branches, and stems that provide coverage from trees when viewed from above, while urban forests are collections of trees and other vegetation found in urban areas, including streets, parks, private yards, and natural green spaces. Together, tree canopies and urban forests play a crucial role in improving environmental quality, supporting biodiversity, and enhancing urban resilience to climate change.

Benefits of Tree Canopy and Urban Forests

  • Stormwater Management: Trees intercept and absorb rainfall through their leaves and root systems, reducing the volume of stormwater runoff. They also slow down rainwater, allowing more of it to seep into the ground and decreasing pressure on stormwater systems.
  • Temperature Regulation: Tree canopies provide shade, reducing surface temperatures and mitigating the urban heat island effect, which occurs when cities become significantly warmer than their surrounding rural areas due to heat-absorbing surfaces like asphalt.
  • Air Quality Improvement: Trees filter air by capturing dust, pollutants, and carbon dioxide, helping to improve air quality and reduce greenhouse gases.
  • Biodiversity: Urban forests provide habitats for a variety of wildlife, including birds, insects, and small mammals, contributing to the ecological diversity within cities.
  • Energy Savings: By shading buildings and reducing cooling needs in the summer, urban trees help lower energy consumption, resulting in cost savings for homeowners and businesses.
  • Aesthetic and Social Value: Trees and green spaces enhance the beauty of urban areas, improve residents’ mental well-being, and create spaces for recreation and community gatherings.
  • Carbon Sequestration: Urban trees absorb carbon dioxide from the atmosphere, storing carbon and helping to mitigate the effects of climate change.
  • Tree Canopy Coverage:
  • The extent of the tree canopy in an area is often measured as a percentage of the land covered by trees. Increasing tree canopy coverage in urban areas is a key strategy in creating sustainable cities that can better handle stormwater, reduce pollution, and provide cooler, more livable environments for their residents.

Urban forests and expanded tree canopies are central to Green Stormwater Infrastructure (GSI) because they naturally manage stormwater, reduce flooding risks, and contribute to the ecological health of cities.

Constructed Wetlands

Constructed wetlands are engineered systems that mimic the natural functions of wetlands to treat stormwater, wastewater, or runoff. They are designed to filter and purify water through natural processes involving plants, soils, and microorganisms, while also providing ecological benefits like habitat creation and aesthetic improvement.

Types of Constructed Wetlands

Surface Flow Wetlands: These wetlands resemble natural marshes, with shallow water flowing over a vegetated surface. They are ideal for removing sediments, nutrients, and pollutants from the water.

 Green Stormwater Infrastructure | Constructed Wetlands
Green Stormwater Infrastructure | Constructed Wetlands

Subsurface Flow Wetlands: In these systems, water flows through a gravel or sand bed planted with vegetation, keeping the surface dry while allowing water to filter underground. This design reduces odors and mosquito breeding and is better suited for urban environments.

Key Components of Constructed Wetlands

  • Vegetation: Wetland plants like reeds, rushes, and cattails are essential for filtering pollutants and promoting microbial activity that breaks down contaminants.
  • Soil and Gravel: These materials help trap sediments and provide a medium for beneficial microorganisms that decompose organic matter and pollutants.
  • Water Flow: Constructed wetlands are designed to slow down water flow, allowing time for contaminants to settle, be absorbed by plants, or be broken down by microbes.
  • Benefits of Constructed Wetlands:
  • Water Quality Improvement: They filter pollutants such as nutrients (like nitrogen and phosphorus), heavy metals, oils, and sediments from stormwater or wastewater, improving the quality of the water that eventually enters rivers, lakes, or groundwater.
  • Flood Control: Constructed wetlands store and slow down stormwater, reducing the risk of flooding and erosion during heavy rains.
  • Habitat Creation: They provide habitats for wildlife such as birds, amphibians, insects, and other species, increasing biodiversity in urban or rural areas.
  • Aesthetic and Recreational Value: Constructed wetlands can be integrated into parks, residential developments, or public spaces, adding natural beauty while offering opportunities for education and recreation.
  • Cost-Effective: Compared to traditional water treatment facilities, constructed wetlands are often more affordable to build and maintain, while requiring less energy to operate.
  • Constructed wetlands are a vital part of Green Stormwater Infrastructure (GSI), as they naturally manage and treat stormwater, reduce pollution, and support biodiversity while being more sustainable than conventional water treatment systems.

Rainwater Harvesting

Rainwater harvesting is the practice of collecting and storing rainwater for beneficial uses, such as irrigation, landscaping, and even potable water supply in some cases. It involves capturing rainwater from surfaces like rooftops and directing it into storage systems, such as barrels or tanks, where it can be used later.

Key Components of Rainwater Harvesting

  • Catchment Area: This is typically the roof of a building, where rainwater is collected as it falls. The surface should be made of materials that do not contaminate the water, such as metal or tiles.
  • Gutters and Downspouts: These systems direct the collected rainwater from the catchment area into storage containers. Proper sizing and installation are essential to efficiently transport water.
  • Storage System: Rainwater is stored in tanks or barrels made of various materials (such as plastic, fiberglass, or concrete). The size of the storage system depends on the amount of rainfall in the area and the intended use of the water.
  • Filtration and Treatment: To ensure the quality of the collected rainwater, it may need to be filtered or treated before use, especially if intended for drinking or irrigation. This can involve sediment filters, UV treatment, or other purification methods.

Benefits of Rainwater Harvesting

  • Water Conservation: Rainwater harvesting helps reduce reliance on municipal water supplies, conserving precious water resources and promoting sustainable water management.
  • Cost Savings: By using harvested rainwater for non-potable uses like irrigation, homeowners and businesses can lower their water bills.
  • Stormwater Management: Collecting rainwater reduces runoff, mitigating flooding, erosion, and water pollution. It also alleviates pressure on stormwater drainage systems.
  • Groundwater Recharge: Properly designed systems can help recharge groundwater supplies by allowing some of the collected water to infiltrate into the ground.
  • Drought Resilience: Rainwater harvesting can provide a supplemental water source during dry periods, enhancing resilience against drought conditions.
  • Applications of Rainwater Harvesting:
  • Residential Use: Homeowners can collect rainwater for watering gardens, flushing toilets, washing cars, or even for drinking after proper treatment.
  • Agricultural Use: Farmers can use harvested rainwater for irrigation, reducing the need for groundwater or surface water.
  • Community Projects: Schools, parks, and community gardens can implement rainwater harvesting systems to promote sustainability and engage the community in conservation efforts.
  • Rainwater harvesting is an essential part of Green Stormwater Infrastructure (GSI), contributing to sustainable urban water management while providing multiple environmental, economic, and social benefits.

GSI aims to improve water quality, reduce flood risk, and create greener urban environments by integrating stormwater management into landscapes. It’s an important tool in urban planning for adapting to climate change and improving the sustainability of cities.

Scroll to Top