Whereas you might consider soil erosion an agricultural issue, it’s also a problem in cities. Urban environments greatly disturb the natural world, exposing dirt to wind, rain and human activity. Even driving your car or strolling down the sidewalk causes vibrations underground, while constructing new skyscrapers removes topsoil and introduces pollutants to the natural world. 

As global cities build resilience through sustainability goals, experts seek ways to conserve urban soils, including employing moss and trees.

The Causes and Impacts of Soil Erosion in Urban Areas

Land conversion, from dense forests to the construction of roads and buildings, strips metropolitan areas of vegetation, leaving the ground susceptible to disturbances. Exposure to heavy precipitation, worsened by impervious surfaces, intensifies stormwater runoff and flash floods that wash sediment away.

The consequences of this phenomenon are damaging to communities and the surrounding environment. For instance, heavy metals may accumulate in urban soils, becoming a significant source of contamination. Rains may then disperse the polluted earth throughout the city and into your water supply, posing dire health risks to you and your neighbors.

Soil is also crucial for foundation stability to prevent sloping and infrastructural collapse. Of course, urbanization results in more construction sites, which impacts the land. Consider how natural erosion occurs at 1.4 tons annually, but building new structures erodes soil at a 700 to 40,000 times higher rate. Therefore, unsettled land and weakened support can compromise your apartment building’s safety.

Innovative Soil Conservation Techniques in Sustainable Cities

Soil erosion in cities happens much faster than the ground can recover, leading experts to explore various conservation strategies to make metropolises more sustainable in the long term. Here are three innovative ways your location may prevent the ground from wearing away. 

1. Earth-Retaining Structures

Earth-retaining structures are not a new solution for combating soil erosion. In fact, the ancient Egyptians used reed gabions — a woven cage predating modern wire mesh — to protect against Nile flooding. Eventually, civilizations began using other materials, like rocks, timber and concrete, to reinforce the earth. In the 1970s, this approach to soil retention became popular in the United States for its cost-effectiveness and simple construction. 

When employing earth-retaining structures, you can choose between gravity and cantilever systems. Gravity systems rely on friction and weight support to resist soil pressure. Meanwhile, a cantilever wall uses its passive resistance and soil weight to counteract the pressure from the dirt it maintains. Both methods require soil layers between two and three times the wall’s height for stabilization.

2. Soil Erosion Construction Solutions

Cities have implemented several strategies to prevent ground wear. For instance, Tampa, Florida, recommends construction site operators lay temporary gravel at entrances and exits, erect silt fences, and construct block and gravel inlet protection around storm drains to prevent obstructions.

Meanwhile, Tulsa, Oklahoma, recommends preserving as much vegetation on the construction site as possible, minimizing soil exposure, slowing runoff and stabilizing disturbed soil quickly. Covering the soil with mulch and plants can also help secure the ground. 

3. Green Infrastructure

Water cannot drain into concrete and asphalt because these materials aren’t porous. Instead, runoff picks up contaminated soil and flows into lakes, streams and marine environments. Over 80% of ocean pollution derives from human activity on land, such as chemical leaching, which may cause toxic algal blooms and damage aquatic ecosystems. 

Sustainable infrastructure — green roofs, urban forests and rain gardens — can curb stormwater runoff and improve water quality for city residents. Living roofs consist of vegetation and soil over a traditional covering. According to the U.S. General Services Administration, green roofs slow stormwater from buildings by 65% and the flow rate by three hours.

Combating CO2 Emissions With Moss and Trees

Cities greatly benefit from moss and trees to maintain soil structure and sequester urban carbon dioxide (CO2). Moss can absorb nearly 6.43 billion metric tons more CO2 than land without vegetation. This rapidly growing ground cover retains water and offers a substrate for other plants to flourish, especially in rooftop gardens. 

You could also plant trees in your neighborhood to capture and store CO2 and stabilize the soil. In one study of national urban forests, trees sequestered 33,000 metric tons of CO2 in new growth annually. They also provide shade, filter air pollutants and help manage the urban heat island effect. 

Although trees provide a better long-term CO2 storage solution with widespread advantages for cities, moss also offers a quick solution to enhance and strengthen urban soil for a sustainable urban landscape. 

How to Conserve Soil in Your City

Implementing soil conservation and erosion control in cities presents numerous challenges, such as limited space for large-scale initiatives and outdated zoning regulations. Fortunately, there are many ways you can promote soil sustainability where you live.

• Call your local politicians to discuss policy changes for green infrastructure and best construction practices.
• Mobilize community members to raise awareness and support.
• Support community garden projects.
• Plant trees in your local parks.
• Participate in citizen science projects to monitor erosion and collect samples. 

Soil Conservation Is Necessary for Building Sustainable Urban Areas

Comprehensive soil conservation is required to improve cities’ sustainability and resilience against today’s most pressing environmental issues. These techniques are just as crucial for stabilizing urban development projects as they are for strengthening local ecosystems and sequestering CO2.