THIS refers to the article ‘On shaky ground’ (June 30), which is a timely reminder of the hazards of unregulated development taking place across Karachi. Another danger that appears to have gone unnoticed in the discourse on construction safety is land subsidence.

The area where a building recently collapsed in Florida, US, had also showed signs of land subsidence.

The region saw subsidence over larger areas because the structures were built on reclaimed wetland.

Further, areas where land is subsiding are more likely to experience the serious effects of sea level rise.

This threat is of serious concern to phase VIII of DHA, Karachi, but prices there are the highest among all the DHA phases, indicating that the public is oblivious to real and imminent threats of land subsidence and sea level rise.

Land subsidence can be caused by a variety of factors, including groundwater pumping.

This risk is also applicable to Karachi, due to the inefficient and deteriorating water supply system across the city, and increased use of boring wells by citizens to extract groundwater.

Groundwater extractions deplete aquifer systems and cause the sediments to compact and the land surface to sink, or subside. Land subsidence can damage structures, such as wells, buildings and highways.

This problem has seriously affected major cities, such as Jakarta and Mexico City.

Unless the threats of unregulated construction, land subsidence, faulty drainage and water supply system are urgently and adequately addressed, the future of this city by the sea and welfare of its citizens will remain doubtful.

Awareness and actions on these issues are therefore immediately needed.

Tariq Hasan

Karachi

Published in Dawn, July 3rd, 2021