Tag Archive for: green infrastructure

How Green Infrastructure Could Change Construction, and the World

The groundswell of one concept could finally awaken the industry of infrastructure design from its long, concrete-gray slumber.

Green infrastructure is that concept, and every landscaper interacts with it — whether they know it or not.

In plain terms, green infrastructure is nature. The entire ecosystem and all its functions contribute to it. Geology, soils and roots, plants, waterways, insects, animals, us, and the atmosphere are its ingredients.

But green infrastructure also provides a creative framework that we can use to shape the world around us as designers. By working with it, we can emulate, restore, and directly use natural processes in buildings, roads, parks, and anything else we design.

     View this post on Instagram           

 

A post shared by SEE MONSTER (@seemonsteruk)

The idea that nature contains its own infrastructure that we can adopt is relatively new. However, the economic value of ecosystem services like food provision and climate resilience is well-established.

Green infrastructure might be key to unlocking the solid foundation and bright future we all aspire to.

Gray Infrastructure

Building nature-focused systems addresses a glaring weakness, especially in the United States. Lawmakers found common ground in 2021’s Bipartisan Infrastructure Law, which pledged $350 billion to update aging public resources. The American Society of Civil Engineers (ASCE) had graded roads and other government-owned infrastructure a D+ by the time of the law’s passage.

the golden gate bridge above a concrete-covered landscapeSan Francisco; (photo/Bill Abbott via Flickr)

This “gray” infrastructure usually bypasses natural systems and, as a general rule, weakens over time. Sewer systems are a great example of critical infrastructure becoming obsolete in some areas.

Stronger storms and shifting seasons have contributed to catastrophic floods in cities from New York to Karachi, Pakistan. But the concrete-and-steel drainage systems built to divert water from these largely impervious-covered cities are aging past their useful life, a 2019 study in the journal Resources, Conservation and Recycling found. They face scaling and maintenance challenges because they block nature’s hydrological cycle in order to create their own.

     View this post on Instagram           

 

A post shared by CNBC (@cnbc)

Green Infrastructure

Systems that mimic and/or utilize nature’s more potent ability to absorb and redirect stormwater can help. Green infrastructure is any built system that supports these or other natural processes. Permeable pavement, green roofs, and bioswales are popular examples.

a terraced building with planted patios and roofsPatio plantings on a terraced design; (photo/NNECPA via Flickr)

Most of us are familiar with green roofs, which utilize plants to cool down otherwise unused space on buildings. Terraced designs with planted balconies can accompany green roofs to reduce wind tunnel effects in dense urban developments and provide even more shade. Finally, shade canopies like the louvers in the photo at the top of this page perform similar functions.

Permeable pavement can replace concrete in some applications to increase “infiltration,” or soaking, of water into soils. Benefits include slowing the pace of stormwater runoff, and increasing water filtration.

cross section of permeable paver design with layers down to uncompacted soilPermeable paver design; (photo/Liangtai Lin via Flickr)

Bioswales, too, slow and filter stormwater. But they use plantings, root structure, and buried drainage systems to do it. Bioswales can replace common concrete drainage channels to function more like natural tributaries. The plants retain and decompact the soil, which allows efficient absorption of stormwater, and a buried, permeable drainpipe channels the runoff to a river or reservoir.

a planted bioswale for drainage(Photo/Wiki Commons)

This engineering concept is called green stormwater infrastructure. And in areas like Central Texas, where flooding and droughts are both problems, it can remedy both.

This illustration from the Hill Country Alliance below describes how our natural and built systems can work together.

     View this post on Instagram           

 

A post shared by Hill Country Alliance (@hillcountryalliance)

In our limestone karst geology, underground aquifers store groundwater. Rainwater fills them by “infiltrating,” or soaking into, the soil, then filtering through the porous rock below.

The left side of the diagram represents our rangelands. The soil in these high plateaus absorbs some stormwater, and the rest drains down to rivers like the Pedernales and the Colorado.

Cities like Austin then build infrastructure to direct and divert it, like the reservoir on the right side of the diagram.

The aquifer can refill through seepage, but compacted soils and impervious ground cover increase runoff and restrict infiltration. That makes recharge zones highly important, as the center of the illustration shows.

Dense native plants in these areas decompact the soil as roots grow downward toward the aquifer below. So when rain falls or drains into the area, it filters underground more directly.

A diver in a karst aquifer; (photo/International Year of Caves and Karst)

OK, But Why Does it Matter?

Imagine cities in our area engineered toward aquifer recharge. Green roofs and terraced buildings cool impervious surfaces and reduce Structures like bioswales and permeable pavement loosen the concrete-and-steel grids that compact soils and shed water quickly.

Direct results include healthy, absorbent soils with stronger plant and wildlife communities. Benefits cascade from there.

Aquifers recharge faster and more regularly. It’s hard to overstate the upside of this function, but easy to illustrate it with one statistic: 55% of all Texas water comes from aquifers (as of 2019).

Beyond that, trees and understory plants thrive, collecting CO2 and cooling off the surrounding surfaces. These green areas also support pollinators and pest predators, like spiders and bats. Humans enjoy the boost in mental and emotional well-being that proximity to nature brings, which is well-documented.

crowds gathered at a swimming holeAustin’s “Barking Springs,” one basic example of the kind of infrastructure that will grow more critical as cities expand; (photo/David Ingram via Flickr)

Most vitally, green infrastructure makes our communities resilient rather than vulnerable to extreme weather. Areas with healthier soils and better drainage will withstand floods better. Shadier surfaces add comfort in extreme heat and help reduce convection in heat islands. And a bigger underground water supply can provide security during severe droughts.

Examples at scale exist increasingly, all over the world.

     View this post on Instagram           

 

A post shared by Landscape First (@landscape.first)

Large-scale opportunities to completely replace concrete structures with natural solutions exist, too. One such strategy is natural streambank stabilization of waterways that function as drainage.

Streambank stabilization almost always requires some infrastructure. Populated areas change these waterways, often increasing water load and associated erosion.

The gray infrastructure method is to turn them into concrete troughs. But green methods like elevated soil lift (ESL) construction and selective planting can also stabilize these channels’ banks. Like concrete, this solution provides critical water diversion. But it creates absorption and wildlife habitat that concrete does not.

Not only that, but because it is alive, an engineered, planted streambank will strengthen over time rather than weaken. In fact, this is the case in all green infrastructure with proper implementation and plant selection.

     View this post on Instagram           

 

A post shared by Nigel Dunnett (@nigel.dunnett)

While gray infrastructure still has viable applications for the foreseeable future, green infrastructure can help conserve the natural resources that will protect that future.

Public funding for conservation in Texas over the last three decades adds up to $2.2 billion. Studies have shown that every $1 invested in conservation returns $4 to $11 in ecosystem services like clean air and water and reduced flood risk. And every $1 invested in land conservation for water protection helps avoid $6 in water infrastructure costs.

“Nature-based solutions can be part of the solution,” the Environmental and Energy Study Institute said. “They have a smaller carbon footprint than gray infrastructure and usually sequester carbon — plus they literally grow over time!”

What is Ecological Landscaping?

Ecological landscaping seeks to implement a vision of human-designed outdoor spaces that integrate into natural processes. In action, it leverages natural sciences to create healthy communities of diverse native plants and wildlife.

It promotes the costless ecological benefits that support all life. And it satisfies human needs and aesthetics.

Ecological landscaping works to restore any ecosystem by fostering healthy soil and supporting pollinators. It can resolve trenchant infrastructure shortfalls. Examples include heat islands and wasteful stormwater drainage in urban areas, and soil erosion and monoculturing in rural areas. It can also ease pressure on existing, engineered solutions to these problems.

Finally, it can result in colorful, attractive landscapes.

a planted rain garden with a birdbath, both filled with waterFunctional and appealing

Designers of ecological landscapes seek to plan communities as unified systems where natural and manufactured components work together. Arguably, every landscape design must integrate into a “novel ecosystem” — a system of biotic, abiotic, and social components defined by human influence.

The key goals of these landscapes serve the three pillars of sustainability: economic, social, and environmental benefits. The main factors the ecological landscaper must consider are soil restoration, species biodiversity, and plant propagation. All these measures build educational and social opportunities, and support functioning economies in the long term.

two workers prepare a plant bedPhoto: Marc Opperman

“Ecology-based design emphasizes stimulating growth of soil biotic populations and maximizing above and below-ground biodiversity. Specific methods and materials vary by site,” said Rick Martinson, Ph.D. in Horticulture and owner of WinterCreek Restoration & Nursery. “But every design strives to create a fully functional landscape that doesn’t rely on artificial inputs.”

Prioritizing ‘Ecosystem Services’

Imagine a typical city or suburb. Blocks are laid out in squares, lined with impermeable structures that reflect heat and do not absorb water. Natural materials are relegated to the medians, margins, and other in-between spaces.

A typical suburbPhoto: Harry Thomas via Pexels

In this standard format, cities are linear designs that usually consume water and produce waste at high rates. Stormwater flows faster over hard surfaces, causing erosion and depositing pollutants downstream.

The overall effect is to interrupt nature’s cyclical, filtering processes.

an illustration showing how cities affect natural water cyclesIllustration: University of Florida Institute of Food and Agricultural Sciences

These impervious designs also obstruct the flow of “ecosystem services.”

These free, nature-provided functions are the reason all human life exists. They allow life on multiple levels, from growing food to filtering water, controlling disease, and supporting recreational and cultural opportunities.

ecosystem services categories including provisioning, regulating, cultural, and supporting

Infrastructure that ignores or restricts ecosystem services fails to capitalize on these vital, zero-cost resources. But ecological landscape designers can remediate these deficiencies. The critical path is to harness natural elements to perform infrastructural functions (called “green infrastructure”).

an illustration desribing a rain gardenPhoto: thewatershedproject.org

One common example of green infrastructure design is a rain garden, a landscape structure that mimics natural water cycling. Rain gardens can cause stormwater to infiltrate soils and recharge aquifers, reducing flood and pollution hazards that most impermeable drainage structures worsen.

Even more simply, trees, vegetation, and green roofs can reduce heat island effects. They shade reflective surfaces, deflect solar radiation, and regulate atmospheric moisture.

     View this post on Instagram           

 

A post shared by 07sketches-Architecture&Design (@07sketches)

Biodiversity is Key

But creating healthier plant communities is more complex than just installing more green things. Biodiversity among species is a major driver of ecosystem structure and function. So intentional species selection is critical to any ecological landscaper’s plant plan.

As well-designed plant communities mature, they tend to increase in resilience and benefit. Consider the rain garden below (swipe right for seasonal progress).

     View this post on Instagram           

 

A post shared by Maas Verde Landscape Restoration (@maasverde_atx)

Every size ecosystem needs a wide variety of species to function beneficially. In fact, a non-biodiverse environment could not produce any of the ecosystem services listed above.

We need multiple species of pollinators for food production. Plant communities with multiple cohabitating species resist disease better, limiting failure. Stronger plant communities retain and enrich soil, limiting flooding and supporting resource security. And research has established links between exposure to nature and mental well-being. (The Royal Society further explains these concepts in a colorful 90-second read.)

Landscapes like rain gardens, butterfly gardens, and even hardscape projects should include diverse plantings. Designers should prioritize native species, because these plants have adapted to their local ecosystem for thousands of generations.

Yes, we mainly live in novel ecosystems. But these changes point even more directly to the benefits of native plants.

“Seven to eight generations of human management have affected most soils in our area,” explained Ted Maas, president and founder of Maas Verde. “We can perform amendments, but that creates human influence, too. So plants that have adapted to these soils over long periods of time are more likely to thrive.”

As Martinson points out, “fully functional landscapes” are the goal. The effective ecological landscape designer considers links between all species at a site. This also factors in migratory and resident wildlife, including insects and soil biota.

Monarchs on Gregg’s mistflower (top); Ruby-throated hummingbirds on lantana. Photos: Texas Parks and Wildlife Department, Travis Audubon

Soil Health and Long-Term Benefits

Creating human-friendly systems where plant communities also thrive is the overarching goal of ecological landscaping. But the benefits of these landscapes must propagate in the soil first.

Many areas, urban and rural, experience deeply degraded soil conditions due to a range of causes. Ecological landscaping needs to address erosion and sterility in soils.

An example of gully erosion, in which fast-moving water removes soils by cutting channels in landscapes

Virtually all sites that have undergone conventional construction or industrial-scale agriculture exhibit these conditions.

At a typical construction site, crews prepare the area by scraping away vegetation and topsoil down to a depth of several yards. Materials that replace it are usually impermeable (concrete, asphalt) or do not support the site’s original ecology.

This creates several problems. Applying hard surfaces over soil compacts it, increasing erosion and runoff and decreasing nutrient exchange. And plants that are unsuited to their location tend to root poorly, require chemical treatments, or fail.

Roots naturally decompact and aerate soils. Decomposition and water infiltration in soils stimulate nutrient cycling, and biodiversity of species builds resilience against stressors. Ecological landscaping performs these functions.

Illustration: Institute for Local Self-Reliance

This generates lasting resilience, leading to long-term resource security in communities. Once the system establishes itself, it becomes more valuable as it propagates.

An ecological landscape is “an investment that tends to increase in value as plants grow and become more self-sufficient. Studies have shown that capital costs can be reduced by 15 to 80 percent by using green infrastructure in stormwater management, paving, and landscaping,” Oregon State University’s Gail Langelotto and Singe Danler explain.

Maintenance costs represent one clear example of these savings. Since native plants are adapted to their site, they require little chemical treatment or irrigation (if any).

‘Rethinking’ Landscape Design

Traditional landscapes conform to traditional human infrastructure designs — linear, decoupled from natural processes, and waste-producing. Ecological landscapes will alter these designs and perform new, integrated functions within the novel ecosystems that result.

A bioswale on an urban street. Photo: Department of Energy & Environment

“Ecological landscaping does not necessarily replicate natural landscapes, although it may include parts of them; rather, it incorporates natural systems and processes into a human-centered design. By rethinking landscape design and modifying some of its objectives, we can make use of the many services natural ecosystems freely provide, often more efficiently and economically than built systems.”

-S. Danler, G. Langellotto

The quantifiable benefits of ecological landscaping are substantially unknown, mainly because the trade is so nascent. While its rudimentary principles have existed for well over half a century (it’s not functionally wrong to think of the Barton Creek Greenbelt as one giant rain garden), the industry is young.

Ecosystems need time to develop and mature, and society needs time to accept change. People generally like it when their surroundings seem cohesive and conform to the status quo. Transitioning the aesthetic ideal of a landscape from the conventional lawn (perfectly manicured but often dysfunctional) to the native plant garden (wilder but functional) will take time.

A conventional turfgrass lawn and plantings (left) and rain garden (right)

Installing ecological landscapes at scale can ease this pain point. More importantly, linking more naturally landscaped areas together makes the habitat far more viable for the plants and wildlife it hosts.

Ecological landscapes can look different, or messy, but design techniques like critical species selection and clean edging can add intentionality. Below grade, the soil will store the benefits of increased biodiversity and erosion control for future generations.

Maas Verde believes creating aesthetic, functioning landscapes will spark widespread adoption of these re-imagined structures. And that through this process, we can restore ecosystems.