River deltas face threats other than rising sea levels. Physical geographer Philip Minderhoud (Utrecht University and Deltares Research Institute) has studied soil subsidence in the Mekong delta, and managed to raise the issue with the Vietnamese government. Minderhoud will defend his dissertation in University Hall at Utrecht University on 15 February.
In the late 1980s, Vietnam transitioned towards a market economy, which resulted in increased agricultural production, population figures, and urbanisation, all of which heightened the demand for ground water. But as Minderhoud wrote in his dissertation, pumping out ground water exacerbates the problem of soil subsidence. “The area also has a soft, shallow soil layer. The growth in infrastructure that has accompanied the past few decades of economic development has placed an extra burden on the soil. This is another reason the soil is subsiding, which makes the sea level rise more quickly in relation to the land. It’s as if the delta is sinking into the sea. Plus, salt water is pushing ever farther land-inwards, so the delta also faces the problem of salinization.”