Land subsidence is the gradual sinking or lowering of the earth’s surface, which can have devastating consequences for human and natural systems. Land subsidence can cause damage to buildings, roads, bridges, pipelines, and other infrastructure, as well as increase the risk of flooding, erosion, saltwater intrusion, and loss of biodiversity. Land subsidence can also affect the availability and quality of water resources, which are essential for human health, food production, and economic development.
Land subsidence is not a new phenomenon. It has been occurring for centuries due to natural processes such as tectonic movements, volcanic activity, and sediment compaction. However, in recent decades, land subsidence has been accelerated and exacerbated by human activities, especially population growth and its associated demands for land, water, energy, and food.
According to the United Nations, the world population reached 7.8 billion in 2020 and is projected to grow to 9.7 billion by 2050. This rapid population growth implies increasing pressure on the earth’s resources and ecosystems, which are already strained by climate change, pollution, and overexploitation. One of the most significant impacts of population growth is the change in land use and land cover, which refers to the human modification of the natural environment for various purposes such as agriculture, urbanization, and industrialization.
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How Population Growth Drives Land Subsidence
Land use and land cover change is one of the main drivers of land subsidence, as it alters the physical and hydrological properties of the soil and the underlying rock formations. Some of the common causes of land subsidence related to land use and land cover change are:
- Groundwater extraction: Groundwater is a vital source of water for domestic, agricultural, and industrial uses. However, excessive and unsustainable groundwater pumping can cause the depletion of aquifers (underground layers of water-bearing rock or soil) and the compaction of their sediments. This results in a loss of pore space and a reduction in the volume and thickness of the aquifer, which leads to land subsidence. Groundwater extraction is one of the most widespread and severe causes of land subsidence worldwide, affecting regions such as Mexico City, Bangkok, Jakarta, California, and many others.
- Mining: Mining is the extraction of minerals and other valuable materials from the earth’s crust. Mining activities can cause land subsidence by creating voids or cavities in the subsurface, which can collapse or settle over time. Mining can also affect the groundwater flow and pressure in the surrounding areas, which can induce or aggravate land subsidence. Mining-related land subsidence can occur in both surface and underground min, affecting coal, oil, gas, metal, and other mineral resources.
- Irrigation: Irrigation is the artificial application of water to crops or plants to enhance their growth and yield. Irrigation can cause land subsidence by increasing the evapotranspiration (the combined loss of water from evaporation and plant transpiration) from the soil surface, which lowers the groundwater level and causes soil shrinkage. Irrigation can also cause soil erosion by removing the topsoil layer and exposing the underlying clay or silt layers, which are more prone to compaction. Irrigation-induced land subsidence can affect agricultural lands as well as urban areas that rely on irrigation water.
- Urbanization: Urbanization is the process of population concentration in cities and towns. Urbanization can cause land subsidence by increasing the weight and load on the soil surface due to the construction of buildings, roads, bridges, and other infrastructure. Urbanization can also alter the drainage patterns and reduce the infiltration capacity of the soil, which can affect the groundwater recharge and discharge processes. Urbanization-induced land subsidence can affect both coastal and inland cities, especially those built on soft or compressible soils.
How Land Subsidence Affects Our Future
Land subsidence poses a serious threat to our future, as it can have negative impacts on various aspects of human well-being and environmental sustainability. Some of the main effects of land subsidence are:
- Infrastructure damage: Land subsidence can cause structural damage to buildings, roads, bridges, pipelines, railways, airports, dams, levees, ports, and other infrastructure. This can compromise their functionality and safety, as well as increase their maintenance costs. Infrastructure damage due to land subsidence can also disrupt essential services such as water supply, sewage disposal, electricity, telecommunication, and transportation.
- Flooding risk: Land subsidence can increase the risk of flooding by lowering the elevation of the land surface relative to sea level or river level. This can expose the subsided areas to tidal inundation, storm surges, coastal erosion, and river flooding. Flooding can cause loss of life, property, and livelihoods, as well as damage to crops, livestock, and ecosystems. Flooding can also increase the vulnerability of the subsided areas to climate change impacts such as sea level rise and extreme weather events.
- Water resources depletion: Land subsidence can affect the availability and quality of water resources by reducing the storage capacity and recharge potential of aquifers, as well as increasing the salinization and contamination of groundwater. This can limit the access to safe and sufficient water for human consumption, irrigation, and industrial uses. Water resources depletion due to land subsidence can also exacerbate water conflicts and water scarcity issues, especially in arid and semi-arid regions.
- Biodiversity loss: Land subsidence can affect the diversity and functioning of ecosystems by altering their structure, composition, and processes. Land subsidence can cause habitat loss, fragmentation, degradation, and invasion for various species of plants and animals, especially those that depend on wetlands, forests, grasslands, and other natural landscapes. Land subsidence can also affect the provision of ecosystem services such as carbon sequestration, nutrient cycling, pollination, and recreation.
How We Can Prevent and Mitigate Land Subsidence
Land subsidence is a complex and multifaceted problem that requires integrated and adaptive solutions. Some of the possible measures to prevent and mitigate land subsidence are:
- Monitoring and assessment: Monitoring and assessment are essential for understanding the causes, extent, rate, and impacts of land subsidence, as well as for evaluating the effectiveness of prevention and mitigation strategies. Monitoring and assessment can be done using various methods such as field surveys, borehole measurements, remote sensing techniques (such as satellite imagery, radar interferometry, GPS), and numerical modeling.
- Regulation and management: Regulation and management are necessary for controlling and reducing the human activities that contribute to land subsidence, such as groundwater extraction, mining, irrigation, and urbanization. Regulation and management can be done using various instruments such as laws, policies, plans, standards, permits, incentives, and penalties.
- Adaptation and restoration: Adaptation and restoration are important for enhancing the resilience and recovery of the human and natural systems affected by land subsidence. Adaptation and restoration can be done using various approaches such as engineering solutions (such as raising or reinforcing infrastructure), ecological solutions (such as restoring or creating wetlands), social solutions (such as relocating or compensating affected communities), and institutional solutions (such as improving coordination and cooperation among stakeholders).
Conclusion
Land subsidence is a serious global challenge that threatens our future by damaging our infrastructure, increasing our flooding risk, depleting our water resources, and losing our biodiversity. Land subsidence is driven by population growth and its associated demands for land, water, energy, and food. Land subsidence can be prevented and mitigated by monitoring and assessing its causes and impacts, regulating and managing its contributing activities, and adapting and restoring its affected systems. By addressing land subsidence, we can protect our environment and ensure our well-being for generations to come.
