Land subsidence due to groundwater exploitation in China

Problems

• Land subsidence, the gradual sinking of land, has become a critical environmental issue in China due to extensive groundwater exploitation. This phenomenon is particularly pronounced in the North China Plain, Tianjin, Beijing, and other urban areas, where the demand for water has led to the over-extraction of groundwater resources.
  
  Groundwater is a vital water source for agricultural, industrial, and domestic needs. In China, it accounts for more than 70% of the total water supply in the North China Plain. However, the excessive withdrawal of groundwater has led to significant environmental consequences, including land subsidence. This damages infrastructure and alters the geological and hydrogeological environment, leading to further geohazards. 
  

• Causes of land subsidence in China

  Groundwater, freshwater found beneath the Earth's surface in saturated rock or soil layers, is a vital resource for agriculture, industry, and domestic use in China. However, due to rapid population growth and economic expansion, groundwater extraction rates have soared in recent decades. This excessive withdrawal disrupts the natural balance within aquifers, the geological formations that store groundwater. As water is pumped out faster than it can be replenished, the pore spaces between soil particles or rock fractures become compressed, leading to land subsidence.
  
  The North China Plain (NCP), a major agricultural hub, is a prime example. Here, intensive agricultural practices combined with rapid urbanization have resulted in unsustainable groundwater depletion. Studies utilizing satellite data have revealed significant land subsidence across the NCP, posing a threat to infrastructure like canals, pipelines, and buildings.

• Consequences of a sinking landscape

  Land subsidence caused by groundwater exploitation has severe consequences for China's environment, infrastructure, and economy.
  
  Environmental Damage: Subsidence can disrupt natural drainage patterns, leading to waterlogging and increased salinity in coastal areas. This can harm agricultural productivity and damage ecosystems.
  
  Infrastructure Risks: As the ground sinks, buildings, bridges, roads, and other infrastructure can become damaged or misaligned. This poses a significant safety risk and necessitates costly repairs or reconstruction.
  
  Economic Losses: Land subsidence can render land unsuitable for agriculture or development, leading to economic losses for farmers and businesses. Additionally, the costs associated with infrastructure repairs and mitigation strategies further strain the economy.
  
  The case of Shanghai, a major metropolis built on soft alluvial deposits, exemplifies the challenges. Decades of groundwater extraction resulted in significant subsidence, impacting buildings and threatening coastal defences. While regulations have curbed groundwater pumping in recent years, the city still grapples with the legacy of past practices.

• Conclusion

  Land subsidence caused by groundwater exploitation presents a significant challenge for China's future development. China can address this challenge by prioritizing sustainable water management practices, implementing robust monitoring and regulation, exploring alternative water sources, and adopting appropriate mitigation strategies. Embracing innovation and collaboration in water management will be key to ensuring a future where economic growth and environmental sustainability go hand-in-hand.