Erna, a resident of Jakarta, Indonesia, shares her experience of watching her home sink dramatically over the past twenty years, with flooding becoming a frequent issue. Jakarta is among the fastest-sinking cities in the world, particularly in its northern regions, which are now significantly below road level. The flooding situation has worsened, leading to the loss of vital infrastructure like mosques and ports underwater. Despite numerous efforts to elevate floors and strengthen homes, the ground continues to sink, leaving residents like Erna struggling without the option to move elsewhere.
Global Scope of Urban Subsidence
A study conducted by Nanyang Technological University (NTU) in Singapore looked into 48 coastal cities across Asia, Africa, Europe, and the Americas. The findings revealed that nearly 76 million people live in areas sinking at least 1cm per year between 2014 and 2020. Cities like Tianjin in China have faced severe subsidence, with some regions sinking nearly 19cm annually, leading to infrastructure damage and the need for evacuations.
Causes: Groundwater Extraction and Natural Factors
The issue of subsidence stems from various factors, including construction, mining, tectonic activity, and soil compaction. However, one of the main culprits is excessive groundwater extraction, particularly in rapidly urbanizing Asian cities. When too much groundwater is pumped out, it compresses the soil layers, resulting in sinking land and increased flooding risks. Coastal delta cities like Jakarta, Bangkok, and Shanghai are particularly susceptible to this phenomenon of “relative sea level rise,” where the land sinks even as sea levels rise.
Consequences and Responses
Jakarta is grappling with more frequent flooding, displacing hundreds of thousands of people and prompting Indonesia to construct a new capital on a less vulnerable island. Other cities, such as Lagos in Nigeria, are facing similar hurdles, with many residents lacking access to piped water and turning to groundwater extraction. Coastal defenses like seawalls can create a “bowl effect,” trapping rainwater and exacerbating the flooding situation.
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