Digging Deeper: the Critical Need to Protect and Preserve Our Soils

Did you know that soil is the second largest carbon sink on the planet, surpassed only to the world’s oceans? It plays a crucial role in slowing down the rate of global warming by storing 10% of the carbon dioxide generated by humans.

Despite its pivotal role in sustaining human life, the importance of soil is often overlooked. This is particularly true in urban environments where the construction of towns, cities, and road networks, known as urbanisation, is trapping soil beneath layers of concrete and asphalt, rendering them inaccessible and useless.

But what is it that makes soil so important? Here are the top four benefits of soil in urban areas: 

1. Soil plays a crucial role in mitigating urban heat islands.

A study comparing grass, asphalt, grey sandstone, and white gravel found that grass consistently recorded the lowest surface and surrounding air temperatures. This is because, unlike the other surfaces, grass and soil absorb solar heat rather than reflect it back into the atmosphere. 

You might be wondering, however, how grass manages to maintain the lowest surface temperature despite absorbing heat? The answer lies in the process of photosynthesis, where grass converts thermal heat energy into chemical energy. Not only does photosynthesis help to lower ambient temperatures, but it also increases our oxygen supply as a by-product, making it a win-win situation for both people and our planet.

The issue faced today is minimal grass coverage in cities due to increased urbanisation. The surfeit of concrete reflecting heat back into the surroundings results in temperatures up to 4°C higher than in rural areas - a phenomenon known as the urban heat island effect. This temperature increase, coupled with global warming, could lead to disastrous consequences, especially in the Middle East where temperatures can already reach 50°C during summer months. In 54°C, the risk of heatstroke increases, resulting in more cases of fainting, seizures, and even death.

To combat urban heat island effect, cities must prioritise the creation of green spaces in urban areas. To learn more about urban heat islands and ways to prevent them, check out our blog on building resilience with green urbanisation.

2. Soil fosters biodiversity

Soil is a diverse and complex ecosystem that provides a vital habitat for a vast array of living organisms. From microscopic bacteria and fungi to larger creatures like worms, insects, and even some mammals, the soil is teeming with life. These organisms play important roles in the soil food web, breaking down organic matter, cycling nutrients, and supporting plant growth. In turn, all other levels of life, including humans, rely on these soil organisms for their survival. 

As humans, we depend on pollinators such as birds, bees, and insects for a third of the world's crop production, not to mention the fact that without plants, we wouldn't have enough oxygen to survive. 

For a better understanding of its importance and how we can help to support it, here are 6 reasons why we need biodiversity in urban environments. 

3. Soil helps mitigate the risk of flooding 

Healthy soil plays a vital role in combating floods thanks to its remarkable absorption capabilities. Able to absorb up to 1.5 Olympic-sized swimming pools worth of water per hectare, porous soils prevent surface water accumulation and facilitate infiltration into the water table.

However, urbanisation has caused an increase in impermeable surfaces, leading to greater volumes of stormwater runoff. Aside from polluting nearby water bodies by picking up contaminants such as oil and debris, stormwater runoff and the associated flash floods also poses a significant threat to both people and property. 

To learn more about how we can mitigate the costly damage caused by floods, check out our blog post on turning cities into sponges.

4. Soil is the largest natural water filter on earth

Soil possesses the unique ability to purify water by filtering it through its layers, ensuring that the harmful contaminants picked up by water as it travels over impermeable surfaces do not compromise underground water reserves.

As water passes down through the soil, it undergoes five processes: filtration, absorption, precipitation, oxidation, and microbial activity. These processes, involving physical, chemical, and biological interactions, remove and degrade contaminants, both large and small, before the water enters the water table.

Unfortunately, the filtration capabilities of soils in the Middle East are limited. The high sand content allows water to travel rapidly through the layers, meaning it cannot effectively remove contaminants. As a result, desert regions are more prone to poor groundwater quality.

At Polypipe Middle East, we have multiple solutions that aid in filtration. Our sustainable water management solutions, Polystorm and Permavoid, utilise a patented geotextile for enhanced filtration. The geotextile wraps around these subsurface geocellular tanks, enabling water to pass through as it travels down through the sandy soil. The geotextile is composed of a blend of hydrophilic (water-attracting and oil-repellent) and hydrophobic (oil-attracting and water-repellent) fibres, allowing only pure water to enter the tank. These fibres work by trapping contaminants and breaking them down through microbial processes, in much the same way as soil. The result is a self-maintaining water management system, ideal for applications near sensitive aquifers or source protection zones.

For a deeper understanding of how geotextiles work, read our blog on the hidden heroes behind sustainable urban water management.

In addition to their ground-breaking filtration capabilities, Polystorm and Permavoid can also be used for many other applications. By mimicking the natural water management capabilities of soil, these systems can also help realise all the other aforementioned benefits.

For instance, Permavoid can serve as a zero-energy, subsurface irrigation system, providing a more sustainable and cost-effective way to maintain green spaces in arid climates. As noted above, these green spaces will help to reduce urban heat island effect, increase biodiversity, and reduce flood risk. 

Permavoid’s 93% void ratio offers excellent water storage capabilities, and its use of capillary cone technology allows water to be extracted from the tank only when needed. This demand-based approach helps to minimise water wastage due to evapotranspiration, ultimately reducing overall water demand. This is a particularly useful feature in arid climates where green spaces rely heavily on irrigation for sustenance.

For greater flood management, Polystorm can be installed deep underground to capture large volumes of stormwater runoff before it poses a risk to property and public safety. By collecting and storing stormwater channelled from buildings’ rainwater outlets and surface drains in subsurface tanks, Polystorm can reduce flood risk in urban areas by up to 80%. Like soil, Polystorm treats the water to remove contaminants before releasing it back into the surrounding environment.

For more information on how our filtration and storm water management solutions can elevate your next project, get in touch with our technical team today.

Tel: +971 (0) 4 518 3000 

Email: middleeast@polypipe.com