Soil sealing or soil surface sealing is the loss of soil resources due to the covering of land for

housing Housing refers to a property containing one or more Shelter (building), shelter as a living space. Housing spaces are inhabited either by individuals or a collective group of people. Housing is also referred to as a human need and right to ...

road A road is a thoroughfare used primarily for movement of traffic. Roads differ from streets, whose primary use is local access. They also differ from stroads, which combine the features of streets and roads. Most modern roads are paved. Th ...

s or other

construction Construction are processes involved in delivering buildings, infrastructure, industrial facilities, and associated activities through to the end of their life. It typically starts with planning, financing, and design that continues until the a ...

work. Covering or replacing the

topsoil Topsoil is the upper layer of soil. It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs. Description Topsoil is composed of mineral particles and organic mat ...

with '' impervious'' materials like

asphalt Asphalt most often refers to: * Bitumen, also known as "liquid asphalt cement" or simply "asphalt", a viscous form of petroleum mainly used as a binder in asphalt concrete * Asphalt concrete, a mixture of bitumen with coarse and fine aggregates, u ...

and

cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...

as a result of

urban development Urban means "related to a city". In that sense, the term may refer to: * Urban area, geographical area distinct from rural areas * Urban culture, the culture of towns and cities Urban may also refer to: General * Urban (name), a list of peop ...

and infrastructure construction paired with compaction of the underlying soil layers results in the mostly irreversible loss of relevant soil

ecosystem services Ecosystem services are the various benefits that humans derive from Ecosystem, ecosystems. The interconnected Biotic_material, living and Abiotic, non-living components of the natural environment offer benefits such as pollination of crops, clean ...

. The global rise in population has heightened the need for soil sealing, which in turn leads to the degradation of land. Sealed land is a serious form of land take (use of land specifically for building settlements, roads, and businesses). Soil sealing and land take together leads to the complete loss of soil functions, including its biological, physical and chemical properties.

Impacts

Replacing natural soil with man-made surfaces greatly affects the process of

water infiltration Infiltration is the process by which water on the ground surface enters the soil. It is commonly used in both hydrology and soil sciences. The infiltration capacity is defined as the maximum rate of infiltration. It is most often measured in meter ...

. These artificial surfaces don't allow water to seep through as easily as soil does, leading to increased

surface runoff Surface runoff (also known as overland flow or terrestrial runoff) is the unconfined flow of water over the ground surface, in contrast to ''channel runoff'' (or ''stream flow''). It occurs when excess rainwater, stormwater, meltwater, or other ...

. Additionally, sealing the soil for underground construction alters water movement, further diminishing the soil's natural ability to purify water. In cities, having lots of heat-absorbing concrete and asphalt but not enough cooling vegetation creates heat islands effect. Using human-made materials to cover soil significantly affects its ability to provide essential services like food production. This occurs when fertile agricultural land is converted into buildings and houses. Countries with rapidly growing populations and economies are experiencing notable loss of agricultural land due to development. Soil sealing affects the soil's function as a natural habitat. By completely covering the uppermost layer of soil with man-made substances, it creates fragmented habitats for local

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

. Consequently, this leads to soil

biodiversity loss Biodiversity loss happens when plant or animal species disappear completely from Earth (extinction) or when there is a decrease or disappearance of species in a specific area. Biodiversity loss means that there is a reduction in Biodiversity, b ...

. Further, these impacts worsen with a decrease in the soil's carbon and nitrogen content, as well as its

respiration rate The respiration rate is a parameter which is used in ecological and agronomical modeling. In theoretical production ecology and aquaculture, it typically refers to respiration per unit of time (usually loss of biomass by respiration per unit of w ...

. Soil's intangible benefits such as spiritual connection, learning, and feeling like we belong to this place, are at risk because land take and soil sealing for urban projects are removing recreational spaces in city centers. The impact on cultural services becomes apparent when people worldwide are willing to invest more money in homes located in areas with natural surroundings.

Assessment

Various methods are employed globally to evaluate soil sealing. Some of the methods are * Wet sieving tests * Raindrop impact tests under field and laboratory conditions * Penetration resistance (PR) * Consistency Index (C5–10) * Soil stability Index (StI) * Crusting Index (CI) * Normalized Difference vegetation Index (NDVI) * Normalized Difference Built-up Index (NDBI) * Soil Adjusted Vegetation Index (SAVI)

Soil unsealing

A complete soil unsealing process involves entirely removing any human-made materials like asphalt and cement that obstruct the soil's natural functions, thereby restoring its ability to perform its natural processes. There is very limited research about the process of soil unsealing. Due to mostly irreversible losses, soil unsealing is very difficult. However, by following some steps soil unsealing is feasible. * Transforming urban, barren, or previously used dumping soils into spaces for urban parks, green roofs, and gardens. However, it's essential that the soil is thoroughly decontaminated before any such use to ensure the safety of the environment and the health of those who will be using these spaces. This technique aligns with a European research project in urban planning that emphasizes minimizing construction in green areas and reusing existing industrial sites known as

brownfields Brownfield is previously-developed land that has been abandoned or underused, and which may carry pollution, or a risk of pollution, from industrial use. The specific definition of brownfield land varies and is decided by policy makers and l ...

. * Removing sealed surfaces or buildings to offset the environmental impact of upcoming new urban projects. This approach is employed in the

Walloon Region Wallonia ( ; ; or ), officially the Walloon Region ( ; ), is one of the three regions of Belgium—along with Flanders and Brussels. Covering the southern portion of the country, Wallonia is primarily French-speaking. It accounts for 55% o ...

and Germany, where the "no net land take" principle ensures that urban development plans do not result in a net increase in land usage.

Impacts

Assessment

Soil unsealing

References

See also