Land subsidence due to groundwater exploitation in Bangladesh

Problems

• Groundwater plays a very significant role in the water supply for human activities. As a part of the developing world, Dhaka, the capital of Bangladesh, has experienced large-scale abstraction of groundwater to meet the water supply needs of its rapidly growing population. 
  
  Dhaka was historically reported as a city of migrants and a growing population zone; its 1985 population was 4.9 million, which grew to 7.8 million by 2022. By 2022, it had achieved a mega city status of over 10.2 million. It is now one of the world’s 25 largest cities.
  
  Dhaka is more than 80% dependent on groundwater for domestic, industrial, and commercial water supply. The rise in groundwater use over the last 50 years continues apace, from drilling the first borehole in 1949 to more than 400 public-supply boreholes abstracting an estimated 1.6 Mm3 year-1 against the city’s demand of 2.1 Mm3 day-1. 
  
  New investment in the late 1990s significantly increased the number of public-supply boreholes operated by the utility DWASA. Abstraction from private boreholes, whose numbers have also expanded dramatically to more than 1000, is unquantified but likely to be substantial.
  
  The impacts of land subsidence in Bangladesh are multifaceted. It can lead to the destruction of property, increased flood risk, damage to infrastructure such as roads and bridges, and can disrupt the natural flow of surface water. In agricultural regions, subsidence can affect crop yields by altering drainage patterns and reducing soil fertility.
  
  In the lower Ganges-Brahmaputra Delta region of Bangladesh, land subsidence has been observed at rates of up to 6 mm/year. This is particularly concerning given the country’s vulnerability to sea-level rise and the potential for increased flooding. Studies have shown that areas with high groundwater extraction rates, such as Dhaka, are experiencing significant subsidence, affecting the stability of buildings and infrastructure.

• Conclusion

  Land subsidence due to groundwater exploitation is a complex challenge that requires a multidisciplinary approach. Bangladesh must balance the need for groundwater with the preservation of its land and the well-being of its people. The adverse effects of land subsidence can be mitigated through concerted efforts in policy, management, and community engagement, ensuring a sustainable future for the nation.