Fish farms make land sink

The land is sinking fast beneath fish farms at a delta in China, mainly due to groundwater pumping. The resulting relative increase in sea-level is far more dramatic than any caused by climate change. (Hat tip: Nature News.)

Fish farms are big business in China. Nearly 90 percent of all farmed fish come from Asia, and the Yellow, Pearl, and Mekong deltas have become aquaculture hotspots. To support these facilities, people often pump groundwater — in the case of the Yellow River delta, about 1 billion cubic meters in 2001.

Using satellite-based measurements taken from 2007 to 2011, researchers determined that the land has sunk by as much as 25 centimeters per year in parts of the Yellow River delta. That’s “more than global average sea level rise is expected to produce in a century,” the authors write in Geophysical Research Letters. “Consequently, the largest threat to coastal stability in deltas may not be global sea level rise but effective sea level rise due to land subsidence from groundwater extraction.” Roberta Kwok | 20 August 2013

Source: Higgins, S. et al. 2013. Land subsidence at aquaculture facilities in the Yellow River delta, China. Geophysical Research Letters doi: 10.1002/grl.50758.

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