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UCL Home  /  Geography  /  News & Events  /  News  /  News Archive  /  February 2015  /  Groundwater-fed irrigation reduces arsenic pollution

Groundwater-fed irrigation reduces arsenic pollution

New UCL research reveals key controls on groundwater pollution in Bangladesh

Groundwater-fed irrigation reduces arsenic pollution

In the Bengal Basin of Bangladesh, nearly 50 million people are currently affected by the chronic consumption of arsenic (As) in drinking water.

New UCL research by Dr. Mohammad Shamsudduha (UCL Institute for Risk and Disaster Reduction), Professor Richard Taylor (UCL Geography) and Professor Richard Chandler (UCL Statistical Science), published in Water Resources Research, has examined patterns of As concentrations in shallow groundwater throughout Bangladesh, and reveals that reduced concentrations are associated with areas of higher groundwater-fed irrigation.

There has been a dramatic increase in irrigation using shallow groundwater in Bangladesh since the 1970s, and scientific debate has persisted as to whether this has worsened or improved the As poisoning of water supplies. Much of this debate has so far been informed only by localised studies.

The UCL team assembled a national-scale database, applying advanced statistical techniques to examine a wide range of variables affecting the distribution of groundwater As concentrations across Bangladesh.  They found that, when other factors are accounted for, lower As concentrations are associated with higher groundwater-fed irrigation and groundwater recharge, and a more permeable surface geology. Collectively, these associations suggest that mobile As is flushed from shallow aquifers by groundwater-fed irrigation.

The results have major implications for water management in the Bengal Basin, and other Asian Mega-Deltas currently affected by As in drinking water. They suggest that groundwater-fed irrigation, so vital to food security in the region, also flushes out mobile As from shallow aquifers, so potentially reducing its concentration in drinking water.

These irrigation effects may not be entirely beneficial however, since they imply  a transfer of As from groundwater to the soil, where it may continue to pose a threat to human health and food security.

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Groundwater-fed irrigation, Bangladesh


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