science

Terrawatch: what the world can learn from China’s sinking city


Fissures and sinkholes are the norm in China’s Shanxi province. Intensive agriculture combined with major coal production has put huge pressure on water resources and sucked the earth dry, leaving the city of Taiyuan, with a population of 5 million, and the surrounding area suffering some of the highest subsidence rates in the world. Pipelines, roads, bridges and railways need constant repairs, and gaping cracks in buildings have resulted in entire communities having to be rehoused.

Since 2003, the Chinese government has been trying to solve this problem by diverting surplus water from the Yellow River. Now satellite measurements, published in Remote Sensing of Environment, reveal that this mammoth feat of engineering – taking 1.2bn cubic metres of water every year – has partially solved the problem, with diverted water rehydrating underground pores and reversing the sinking trend.

But it hasn’t worked everywhere: the pore spaces in clay-rich areas cannot be fully reopened. And even where it has worked, the bounce-back is limited.

The biggest successes have been in regions where water diversion has been combined with water conservation, tree planting and modernising irrigation techniques. Other water-stressed and subsidence-prone parts of the world, including the Iranian central plateau, the US high plains and north-west India will do well to learn from the Chinese experience.



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