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Blog Article

Stormwater management: How Capillary Hydroponics can help cities build resilient green infrastructure

Editorial Team
Stormwater management: How Capillary Hydroponics can help cities build resilient green infrastructure
August 29, 2023

Rivers and green surfaces is one way to handle stormwater management

As rapid urbanization continues to reshape landscapes and strain existing infrastructure in cities across the world, the issue of stormwater management has become a pressing concern. In recent years, it has gained even more urgency due to changing weather patterns that have resulted in concentrated rainfall in many areas. As a consequence, several major cities around the world are now grappling with the challenges of effectively managing urban stormwater and implementing sustainable urban drainage systems, or SUDS.

Insufficient management of stormwater can result in overwhelmed sewer systems, erosion, and the degradation of natural water bodies. As rainwater flows through urban areas, it accumulates pollutants from roads, rooftops, and other surfaces and is collected and diverted by what is commonly referred to as 'grey infrastructure’. But these systems are designed to handle historical rainfall patterns and are overwhelmed by erratic and unprecedented rainfall events seen more often in recent years. And when the excessive runoff is discharged from overloaded sewer systems into streams or rivers, it not only pollutes these delicate ecosystems but also causes damage due to flooding.

All this highlights the importance of cities to address stormwater management effectively to ensure the resilience and sustainability of their urban environments, and calls for the adoption of natural stormwater management approaches and sustainable urban drainage system design.

One of the most popular and effective methods for the regulation of stormwater is the implementation of green infrastructure practices, including sustainable urban drainage systems. Green infrastructure involves strategically utilizing interconnected networks of natural and semi-natural elements, such as parks, gardens, wetlands, forests, and water bodies like rivers, lakes, and ponds, within urban areas. Its primary objective is to enhance the quality of urban environments by integrating nature-based solutions into urban planning and development. By incorporating green infrastructure, cities can mitigate the impacts of excessive rainfall by creating spaces that can absorb and infiltrate runoff, reducing the strain on existing grey infrastructure systems. Integrating green roofs, rain gardens, permeable pavements, and other sustainable urban drainage systems (SUDS) into urban planning and development facilitates effective management of urban stormwater while promoting the overall sustainability and resilience of urban environments.

In this blog, we will explore the concept of green infrastructure and its vital role in ensuring effective stormwater management, including sustainable urban drainage systems or SUDS. We begin by examining the definitions of green infrastructure as established by the European Union and the United States, highlighting their commonalities and differences. We then discuss the benefits of implementing green infrastructure for managing urban stormwater and explore various types of sustainable urban drainage systems available. Additionally, we introduce Capillary Hydroponics, an cutting-edge subsurface irrigation system designed by Capillary Flow. This innovative system enables the growth of robust and resilient grass in public city spaces typically covered in asphalt and concrete. By embracing the grass growth in these areas, Capillary Hydroponics offers a promising solution to mitigate the impact of excessive stormwater. Grass, known for its natural water absorption capabilities, acts as a sponge, reducing the velocity and volume of stormwater runoff. Through Capillary Hydroponics, cities can establish resilient green infrastructure systems that effectively manage stormwater and contribute to the overall sustainability and resilience of urban environments.

Section 1: What is Green infrastructure?

Green infrastructure is defined differently in the European Union (EU) and the United States (US). In the EU, green infrastructure is seen as “A strategically planned network of natural and semi-natural areas with other environmental features, designed and managed to deliver a wide range of ecosystem services, while also enhancing biodiversity.” It focuses on improving the environment, connecting natural areas, and enhancing citizens’ well-being.

The US definition of green infrastructure primarily emphasizes stormwater management and reducing the burden on sewer systems and surface waters, and is therefore narrower in scope.

According to the Water Infrastructure Improvement Act, passed by the US Congress in 2019, green infrastructure is “…[T]he range of measures that use plant or soil systems, permeable pavement or other permeable surfaces or substrates, stormwater harvest and reuse, or landscaping to store, infiltrate, or evapotranspirate stormwater and reduce flows to sewer systems or to surface waters.” These includes measures like permeable pavements, stormwater harvesting, and landscaping to store, infiltrate, or evapotranspirate stormwater.

While both the EU and US aim to utilize nature-based solutions, the EU definition encompasses a wider range of environmental benefits, whereas the US definition focuses specifically on stormwater management.

Whatever the definition, it is clear that cities in Europe and the US (and across the world) can gain several benefits by implementing green infrastructure practices because it offers a holistic approach to various environmental and health challenges facing them. Its benefits include improved water quality, reduced flood risks, enhanced urban aesthetics, increased resilience to climate change, and the creation of healthier and more liveable communities.

There are several types of sustainable urban drainage systems or SUDS available, each designed to manage stormwater in a sustainable and environmentally friendly manner. Here are some common types:

  • Permeable pavements, city squares and verges: These include surfaces made with grass, porous asphalt, pervious concrete, and permeable pavers that allow rainwater to infiltrate through the surface, reducing runoff and promoting groundwater recharge.
  • Green roofs: These are vegetated roofs that retain rainwater, reduce stormwater runoff, and provide additional insulation and cooling benefits.
  • Rain gardens: Also known as bioretention areas, rain gardens are shallow depressions filled with vegetation and well-draining soil. They capture and treat stormwater, allowing it to infiltrate into the ground and filtering out pollutants.
  • Swales: Swales are shallow, vegetated channels that collect and convey stormwater runoff, promoting infiltration and reducing the velocity of water flow.
  • Detention basins: These are large excavated areas designed to temporarily store stormwater runoff, gradually releasing it into the drainage system to reduce the risk of downstream flooding.
  • Infiltration basins: Similar to detention basins, infiltration basins store stormwater temporarily but also allow it to infiltrate into the ground, recharging groundwater supplies.
  • Constructed wetlands: These are engineered wetland systems that mimic natural wetland processes. They use vegetation, soil, and microbial activity to treat and store stormwater runoff, promoting water quality improvement and habitat creation.
  • Sustainable drainage ponds: These are specially designed ponds that store and treat stormwater runoff, removing pollutants and reducing the volume and velocity of runoff before releasing it into the drainage system.

These are just a few examples of the types of sustainable urban drainage systems available. The selection of a specific system depends on factors such as site conditions, rainfall patterns, and local regulations. Each system contributes to effective stormwater management, reducing runoff, improving water quality, and promoting sustainable and resilient urban environments.

Through the strategic utilization of such green spaces, cities can achieve a harmonious balance between urban development and environmental sustainability. By taking this approach, city authorities not only tackle stormwater challenges but also enhance the well-being and resilience of their communities. With a focus on the advantages it brings, let us now delve into the specific benefits of implementing green infrastructure.

water treatment plant
Stormwater management and sewage occupies a significant part of cities' waterbudget

Section 2: Benefits of adopting green infrastructure practices

  • Clean water: One of the key advantages of green infrastructure is its ability to purify water. Natural areas, such as gardens, wetlands and vegetated buffers, act as natural bio filters, removing pollutants, sediments and impurities from stormwater runoff and improving water quality. This process helps protect water bodies from contamination and contributes to the conservation of aquatic ecosystems.
  • Air quality: Green infrastructure, including trees, lawns and other vegetation, play a vital role in absorbing and filtering pollutants from the air, reducing the presence of harmful substances and enhancing the overall air quality in urban areas. This helps create healthier environments for residents and mitigates the negative impacts of air pollution on public health. Grass also sequesters carbon, absorbing carbon dioxide and storing it in plant tissues.
  • Enhanced quality of life: Green infrastructure also provides valuable space for recreation and leisure activities. Gardens, parks, greenways, and urban forests offer opportunities for physical exercise, relaxation, and social interaction. Access to green spaces has been linked to improved mental well-being, stress reduction, and enhanced quality of life for urban dwellers.
  • Reduces erosion, boosts groundwater: By mimicking natural hydrological processes, green infrastructure allows for the infiltration of rainwater into the ground, reducing the volume and velocity of runoff and preventing flooding and erosion.
  • Aesthetic appeal: The presence of green infrastructure elements enhances the aesthetic appeal of urban areas.
  • Cools urban areas: It is scientifically proven that green infrastructure helps reducing the urban heat island effect and helping cities adapt to rising temperatures associated with climate change.
  • Preserves biodiversity: By enhancing environmental quality, green infrastructure supports the preservation of biodiversity. Natural habitats within green infrastructure networks provide refuge and breeding grounds for various plant and animal species, contributing to the conservation of biodiversity in urban areas. This ecological diversity is crucial for maintaining balanced ecosystems and promoting resilience in the face of environmental challenges.

For detailed resources on the benefits mentioned above, here are some additional resources:

Green Infrastructure Research

Why You Should Consider Green Stormwater Infrastructure for Your Community

Overall, green infrastructure plays a pivotal role in improving the quality of the environment, conserving biodiversity, and enhancing the health and well-being of citizens. Its strategic planning and management approach, coupled with the provision of ecosystem services like water purification, air quality improvement, recreation space, and climate mitigation and adaptation, make green infrastructure a powerful tool for creating sustainable and liveable communities.

The city of Portland, Oregon, US, is a national leader in green development practices and sustainable stormwater management. With an average of 38 inches of rain per year, Portland has successfully addressed stormwater runoff challenges by integrating green roofs, rain gardens, and permeable pavements. This commitment to green infrastructure has improved water quality, reduced strain on sewer systems, and enhanced resilience to flooding and other stormwater-related challenges. Portland's experience exemplifies the positive impact of implementing green infrastructure on urban stormwater management and on the wellbeing of the overall community.

highway in between lush areas of grass
Green infrastructure

Section 3: Capillary Hydroponics as a solution

Capillary Hydroponics, an innovative approach within green infrastructure, provides a unique solution for growing grass in urban areas that are typically covered in asphalt or concrete.

This hydroponic system utilizes specialized technology to enable subsurface irrigation and oxygenation of the grass, promoting optimal root development and growth. One of its key advantages is the significant increase in gas exchange within the rootzone material by as much as 6000%, leading to healthier plant growth and improved nutrient absorption. The system also demonstrates impressive water efficiency, consuming only 15% of the water typically required for traditional grass areas.

That’s not all, the Capillary Hydroponics system has the capacity to even store excess rainwater if required. Its water storage capacity depends on the depth of the gravel layer. So, to take an example, if using 20 cm of gravel, a football field using Capillary Hydroponics can store as much as 459,000 liters of water.

Grass grown using Capillary Hydroponics exhibits remarkable resilience. Unlike regular grass grown on soil, the grass in this system sits on sand and benefits from stronger and deeper roots due to the hydroponic system's watering method. A notable example of this resilience can be seen in the high-footfall areas of Helsingborg, a city in southern Sweden. Read about the Helsingborg case study here.

Picture of city area helsingborg where pavements, parkings etc. has been turned into grass

At the core of Capillary Hydroponics is Capillary Material, formerly known as Capillary Concrete. This patented and engineered polymer-based pervious concrete is the only building material that can rapidly drain water while also moving water up. Invented in 2009, it is also behind one of CapillaryFlow’s most successful solutions, Capillary Bunkers, which has transformed the way the golf industry constructs and maintains bunkers.

Compared to hardscape surfaces and traditional turfgrass, the Capillary Material has superior drainage and drains water at a rate of over 100 mm per hour while still preserving a surface that can be utilized for almost anything.

Embracing strong and resilient grass growth in urban spaces through Capillary Hydroponics offers cities numerous benefits, particularly in stormwater management. Grass naturally mitigates stormwater-related challenges by reducing runoff and preventing flooding. Moreover, growing grass in urban areas contributes to improved water and air quality, enhances aesthetic appeal, reduces noise, promotes biodiversity, and enhances overall well-being. Let's delve into these key benefits further.

  1. Reducing volume and velocity of stormwater runoff: The dense root system of grass acts as a natural sponge, absorbing and holding rainwater. This process helps to slow down the flow of water, allowing it to infiltrate into the soil. By absorbing and storing water, grass reduces the volume and velocity of stormwater runoff, alleviating strain on sewer systems, and minimizing the risk of flash flooding and erosion.
  2. Replenishing groundwater resources: The absorption and retention of stormwater by grass in urban areas helps replenish groundwater resources. As water infiltrates into the soil, it gradually seeps down to recharge underground aquifers, which serve as crucial water sources for drinking water supplies, irrigation, and ecological balance. By contributing to groundwater recharge, grass assists in sustaining water availability and supporting the overall water cycle in urban areas.
  3. Bio filter: Natural grass acts as a bio-filter by effectively filtering pollutants and impurities from water and air as they pass through its root system and blades. The root system of grass plants helps to trap and retain sediment, debris, and contaminants such as microplastics present in stormwater runoff, preventing them from reaching water bodies and improving water quality. Additionally, the blades of grass have the ability to capture airborne particles, such as dust and pollen, and absorb harmful gases, thereby enhancing air quality, making it an effective bio-filter in urban environments.
  4. Soil stabilization: The root system of grass helps to anchor the soil and prevent erosion. When rainfall hits bare soil or compacted surfaces, it can lead to soil erosion and sedimentation in water bodies. However, grass acts as a protective cover, binding the soil together and reducing erosion. This contributes to the overall stability and health of the surrounding ecosystem.
  5. Temperature regulation: Grass has a cooling effect on the surrounding environment through a process known as evapotranspiration. As grass releases moisture into the air through transpiration, it helps to lower the ambient temperature, reducing the heat island effect in urban areas. This cooling effect can improve air quality and create a more comfortable and pleasant living environment at a time heatwaves in Europe and US are becoming commonplace in the summer.
  6. Positive impact on well-being: The presence of grass in urban spaces has been shown to have a positive impact on the well-being of city dwellers. Research suggests that exposure to green spaces, including grassy areas, can reduce stress levels, improve mental health, and enhance overall quality of life. Grass also provides opportunities for recreation, offering spaces for outdoor activities, picnics, sports, and leisurely walks. These recreational opportunities foster community engagement and social interaction, contributing to a sense of well-being and connection among residents.


To conclude, green infrastructure plays a vital role in ensuring effective stormwater management in urban areas.  Integrating green roofs, rain gardens, permeable pavements into urban planning and development, and growing grass in urban public spaces that are normally covered in concrete and asphalt, facilitates effective management of urban stormwater while promoting the overall sustainability and resilience of urban environments.

By utilizing Capillary Hydroponics to grow grass in public spaces as part of their green infrastructure projects, city authorities can effectively manage stormwater while reaping numerous benefits. With Capillary Hydroponics, cities can enhance stormwater management, improve the aesthetic appeal of public spaces, and create more sustainable and resilient urban environments. Capillary Hydroponics is one of the best options for application in urban spaces with high footfall because it enables the growth of strong and resilient compaction-resistant grass. It is an investment that yields long-term benefits for both the city and its residents.


Want to know more about our products?

Would you like to know more about how Capillary Hydroponics can contribute to your Stormwater Management initiatives? Contact us!


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