Oct 4, 2019 01:21 AM
https://cosmosmagazine.com/earth-science...-time-bomb
EXCERPT: . . . As the world’s largest source of fresh water, groundwater is vital for irrigation and global food security, particularly during dry spells. But it’s under increasing threat from human activities and climate change. Already, groundwater extraction exceeds recharge rates from rain and rivers, particularly in areas that are intensively irrigated, depleting this precious resource with “potentially devastating effects on aquatic ecosystems...”
A glimpse into the sustainability of global groundwater extraction for rivers, streams and lakes in the next few decades has revealed a worrying picture. The hydrological model, published in the journal Nature, shows that in nearly 20% of regions that pump groundwater, rivers are already flowing too low to maintain healthy aquatic ecosystems.
By 2050, more than half those localities will have surpassed their environmental flow limits, or streamflow critical point. The most striking finding, says lead author Inge de Graaf from the University of Freiburg in Germany, is that just one small drop in groundwater level will create these critically low river flows. “This shows that riverine water freshwater ecosystems are extremely sensitive to water decline,” she adds.
And in contrast to surface-water use, which has immediate impacts on streamflow, it can take decades for groundwater extraction to show a noticeable reduction of groundwater influx. “Groundwater pumping can thus be considered a ticking time bomb whose ecological effects become visible only years later,” says de Graaf. (MORE)
EXCERPT: . . . As the world’s largest source of fresh water, groundwater is vital for irrigation and global food security, particularly during dry spells. But it’s under increasing threat from human activities and climate change. Already, groundwater extraction exceeds recharge rates from rain and rivers, particularly in areas that are intensively irrigated, depleting this precious resource with “potentially devastating effects on aquatic ecosystems...”
A glimpse into the sustainability of global groundwater extraction for rivers, streams and lakes in the next few decades has revealed a worrying picture. The hydrological model, published in the journal Nature, shows that in nearly 20% of regions that pump groundwater, rivers are already flowing too low to maintain healthy aquatic ecosystems.
By 2050, more than half those localities will have surpassed their environmental flow limits, or streamflow critical point. The most striking finding, says lead author Inge de Graaf from the University of Freiburg in Germany, is that just one small drop in groundwater level will create these critically low river flows. “This shows that riverine water freshwater ecosystems are extremely sensitive to water decline,” she adds.
And in contrast to surface-water use, which has immediate impacts on streamflow, it can take decades for groundwater extraction to show a noticeable reduction of groundwater influx. “Groundwater pumping can thus be considered a ticking time bomb whose ecological effects become visible only years later,” says de Graaf. (MORE)