Sustainably tapping into North Africa's groundwater resources with isotope hydrology

There is more to freshwater resources than meets the eye. While fresh water is visible in the form of rivers, lakes and glaciers, fresh groundwater resources — hidden beneath the Earth — often go unseen. Groundwater is found in spaces within soil, sand and rock, and is stored in, and moves slowly through, aquifers. It accounts for 99 per cent of Earth's fresh water, and, according to the United Nations Educational, Scientific and Cultural Organization (UNESCO), nearly half of the world's urban population depends on it. This dependency on groundwater is expected to grow in light of the effects of climate change.