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Tropical groundwater resources may be climate-resilient: study

Xinhua, December 12, 2015 Adjust font size:

Groundwater may prove to be a climate-resilient source of freshwater in the tropics as intense rainfall favors the replenishment of these resources, according to a new study released Friday by the University College London (UCL).

Dependence upon groundwater to meet rising agricultural and domestic water needs is expected to increase substantially across the tropics where, by 2050, over half of the world's population is projected to live.

A clearer understanding of how these sources are replenished is crucial for developing strategies for groundwater usage that are better adapted to the greater variability in rainfall and river discharge brought about by climate change.

To examine how these resources are replenished, Dr Scott Jasechko from University of Calgary and Professor Richard Taylor from UCL assessed the chemical signatures in precipitation and groundwater at 15 sites across the tropics.

By comparing the stable isotopes of oxygen and hydrogen in water molecules from precipitation and groundwater, it was found that groundwater recharge occurs disproportionately from heavy rainfalls, according to the study.

"Our results suggest that the intense rainfall brought about by global warming strongly favors the renewal of groundwater resources," said Professor Taylor.

But he also said the results simply indicate a tendency towards increased groundwater recharge from extreme rainfall, and other influences on groundwater storage including excessive pumping, substantial changes in total precipitation, and land-use change can undermine and overwhelm this resilience.

Groundwater is an invaluable source of freshwater across the tropics, enabling access to safe drinking water and often used for agricultural irrigation. The long-term viability of groundwater resources, and the livelihoods and ecosystems sustained by it, therefore relies on the replenishment of these sources.

"Groundwater is a life-sustaining resource for many people in the tropics. Future research will explore how the combination of climate change and pumping will impact the availability of groundwater supplies across the tropics," said Dr Jasechko. Endit