Subsidence

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Abandoned coal mine subsidence stablization project

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Subsidence is the gradual settling or sinking of the Earth's surface with little or no horizontal motion. The phenomenon can result from a variety of factors, including the removal of underground water, the melting of permafrost, mining activities, the extraction of natural gas, oil, or minerals, and the natural compaction of soil over time. Subsidence can lead to significant damage to infrastructure, including buildings, roads, and bridges, and can also impact water drainage and flood management systems.

Causes

Subsidence can be caused by both natural and anthropogenic (human-induced) factors:

• Natural Causes: These include the compaction of soil layers over geological time periods, the dissolution of limestone by groundwater forming sinkholes, and the melting of permafrost which leads to the ground settling.
• Anthropogenic Causes: Human activities such as the extraction of groundwater for irrigation, mining operations that remove support from the Earth's crust, and the extraction of oil and natural gas can lead to subsidence. Urban development, which increases the weight on the soil beneath structures, can also contribute to the process.

Effects

The effects of subsidence can be widespread, affecting both the environment and human structures:

• Infrastructure Damage: Buildings, roads, and bridges can suffer cracks and structural damage, leading to costly repairs and in some cases, the need for demolition.
• Environmental Impact: Subsidence can alter the natural drainage of an area, leading to increased flood risk and changes in water quality. It can also disrupt ecosystems and wildlife habitats.
• Economic Costs: The economic impact of subsidence includes the direct costs of repairing damage to infrastructure, as well as indirect costs such as decreased property values and increased insurance premiums.

Prevention and Mitigation

Efforts to prevent or mitigate the effects of subsidence focus on managing the factors that contribute to the phenomenon:

• Water Management: Regulating the extraction of groundwater to prevent excessive depletion can help reduce subsidence. Recharging aquifers by injecting treated wastewater or stormwater can also be effective.
• Regulation of Mining and Extraction Activities: Implementing stricter regulations on mining and the extraction of oil and natural gas can help minimize the impact of these activities on subsidence.
• Urban Planning: Designing infrastructure to accommodate or resist the effects of subsidence, and limiting development in areas known to be at high risk, can help reduce damage and economic costs.

See Also

• Sinkholes
• Groundwater depletion
• Mining
• Urban planning