Working in harmony with nature can boost mental and physical health, increase productivity and deliver economic benefits. ‘Nature doesn’t need us, we need nature,’ ICE President Anusha Shah reminds us. Nature is a vital ally – we have to look after it like we look after our homes. Civil and infrastructure engineers have an important role to play in incorporating nature into the way we design, build, operate and maintain infrastructure. Nature-based solutions are an important piece of the nature-positive infrastructure puzzle.
Nature-based solutions (NBS) are actions or measures inspired by, supported by, or copied from nature.
They may involve protecting, managing, or enhancing existing natural solutions and creating engineering solutions that mimic natural processes.
If implemented carefully, they can deliver a host of benefits for people and the planet. NBS can:
- Deliver infrastructure services in their own right. For example, they provide mental and physical health benefits by creating green spaces for people to enjoy. This takes pressure off health services and boosts productivity in the workforce, which has economic benefits.
- Complement existing infrastructure, easing maintenance requirements.
- Mitigate climate change impacts, such as flooding.
- Improve habitat biodiversity, woodland and park cover.
- Improve heat resilience, since green surfaces don’t absorb the sun’s rays and release them as heat, like brick and concrete do.
While the potential exists, nature-based solutions haven’t been developed or delivered at scale.
In part, because of a lack of awareness of the NBS options that exist. As such, we’ve shared some of the existing options below;
1. Constructed wetlands
Put simply, wetlands are areas where water meets land. From lakes and lagoons to peat bogs and salt marshes, these ecosystems are homes to a wide variety of species and help to protect us from floods and droughts. They also help us remove carbon from the atmosphere. According to Wetlands International, peatlands cover 3% of the planet’s surface, but store 30% of all land-based carbon. Wetlands can also help with pollution control, helping to treat wastewater
But since 1970, over a third of the world’s wetlands have disappeared, mostly due to:
- Pollution;
- climate change;
- invasive species; and unsustainable development, where wetlands are drained to make way for housing, industry and agriculture.
2. Mangrove restoration
A type of wetland, mangroves are coastal forests made up of the only trees that can thrive in salty water. These purify the water by filtering out nutrients and sediments. Mangroves grow in tropical and subtropical environments – you can find them in Mexico, Argentina, Brazil, Bangladesh, Malaysia, Papua New Guinea, Gambia, Angola and more. Indonesia has the most mangroves in the world. More than 1,500 species rely on mangroves – from herons and crabs to larger mammals like African wild dogs and the so-called ‘fishing cat’. Mangroves also act as natural carbon sinks, absorbing CO2 from the atmosphere.
According to the UN Environmental Programme, they store on average 1,000 tonnes of carbon per hectare in their biomass and underlying soils. They can store this carbon for hundreds of years - if not thousands.
3. Green walls, roofs, alleys, pavements, you name it!
Getting some green on grey infrastructure can have a whole host of benefits.
According to the Royal Horticultural Society, these include:
- Improving storm water management by reducing water run-off
- Providing another layer of insulation for buildings, reducing heating needs
- Offering cooler summers by helping relieve the urban heat island effect
- Providing a home for biodiversity, particularly birds and insects
- Improving air quality
- Reducing noise pollution
- Creating beautiful displays of plants that people can enjoy
Adding some plants to alleys, streets, parking lots and more can go a long way!
Green pavements also incorporate permeable materials that allow rainwater to be absorbed, returning to the soil rather than ending up in the sewer.
Bioswales are nature’s own water filtration systems. They look like shallow channels where polluted stormwater can sit and be purified by vegetation and soil.
They’re placed in long, narrow spaces (like the spot between the pavement and the kerb) and are designed to handle water from areas such as streets and car parks. They direct the water along a desired path and require a specific blend of special soil, gravel, drains and overflow mechanisms to help manage and purify the water.
Rain gardens are essentially bioswales’ cousins. They consist of basin-like pits where rainwater is held until it’s absorbed into the ground. They’re meant to handle water run-off from smaller areas such as roofs and driveways.
Covered in plants, rain gardens can be as beautiful as they are functional. They also provide habitats for biodiversity. Bioswales and rain gardens are techniques often used in sustainable urban drainage systems (SuDS).
6. Living breakwaters
According to the WWF, “well-developed oyster reefs can break up and absorb wave energy protecting coastlines from wave erosion and storm damage”.
Restoring oyster reefs is an NBS solution in its own right, but some engineers have taken this even further and combined these efforts with breakwaters structures.
These are offshore structures, normally made of stone or concrete, that limit wave energy by creating a barrier between open water and the shoreline. They help reduce coastal erosion.
Living breakwaters create an enabling environment for oysters or hard corals to settle.
An award-winning coastal defence system in Staten Island in the US has applied the concept. Aptly named Living Breakwaters, the structure features ridges and grooves that encourage reefs to form.
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