Groundwater-dependent ecosystems are everywhere
A new study shows where dry-land regions likely rely on groundwater.
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A new Nature study maps where groundwater-dependent ecosystems are likely to occur in arid regions around the world, offering a first-of-its-kind map that suggests more than half of these habitats are in areas with declining groundwater levels.
Among other things, the geographic scale of the study illuminates just how important, diverse and prevalent groundwater habitats are. In the dry-land regions that the study maps, groundwater supports springs, meadows, streams and wetlands, including in places like Point Reyes National Seashore (where the photo above was taken).
The point: Groundwater matters locally and globally.
“Until now, the location of these ecosystems has been largely unknown, hindering our ability to track impacts, establish protective policies, and implement conservation projects to protect them,” Melissa Rohde, an ecohydrologist and a lead author of the study, said in a press release with the study’s release earlier this week.
The big takeaway: Groundwater is often invisible to us, but it is used for so much, both within communities and within the ecosystems around us, sustaining unique habitats for endemic species. In biodiverse hotspots like the Ash Meadows National Wildlife Refuge, it is groundwater that makes life possible. But many ecosystems that depend on groundwater face major challenges from human use (over-pumping) and a changing climate. The mapping shows in places with intensive groundwater pumping, such as North America (for instance, California’s Central Valley) or Australia, these ecosystems are more fragmented than in Central Asia, the Sahel and South America.
A lack of protection: The results suggest only about one-fifth (21%) of groundwater ecosystems have some protection. But in many cases, groundwater is not a priority, despite its role in ecosystems and communities. The study’s authors write: “In the race to combat climate change and unprecedented biodiversity loss, global initiatives and land protection often overlook the significance of groundwater in supporting important species, habitats and many critical functions including climate regulation”
Starting to learn more: The water flowing beneath the subsurface might be blind to our eyes — at first glance. But with satellite data, we are beginning to understand it better. The scientists behind the Nature paper, led by the Nature Conservancy and Desert Research Institute, used NASA Landsat data that takes into account multiple variables, ranging from evapotranspiration to land temperature data.
The researchers also used satellite data from the past two decades to determine where groundwater-dependent ecosystems overlap with depleted aquifers. The study found that 53% of these ecosystems, at a large-scale, “exist within regions showing declining groundwater storage trends,” with considerable variation across different continents.
An interdisciplinary approach: Groundwater supports ecosystems, and these habitats in turn support not only wildlife but also human communities that rely on availability of groundwater for drinking water, crops and forage. The study includes an analysis of how groundwater-dependent ecosystems in the Greater Sahel, overlapping with four conflict zones, finding “the overlap between [groundwater-dependent ecosystems] and conflict zones of social vulnerability emphasizes the importance of recognizing the interdependencies between GDEs, climate change, rural livelihoods, food security and social stability in subnational, national and regional protection strategies.”
Expanding existing research: Scientists have been looking at groundwater-dependent ecosystems in the West and specific regions for several years, but this study takes that approach across the planet. “It continues to amaze me that we now have the data and technology to capture and analyze information for places the size of a basketball court or a swimming pool, and that we can do this across the entire globe,” said Christine Albano, a Desert Research Institute hydrologist and a co-author of the study.
Some other stories to watch, groundwater and otherwise:
💧 1/ California groundwater rules stayed in court: A judge in California is putting a temporary pause on a state groundwater order as irrigators challenge the merits of that regulatory decision in court. In April, California officials took action under a landmark 2014 groundwater law, requiring growers in Kings County to monitor their usage. The state action, known as probation, came after the state found local plans to address overuse were inadequate. CalMatters’ Rachel Becker has more on the story.
🏗️ 2/ The Grist’s Jake Bittle looks at what happens when a dam in New Mexico goes out of commission — three summers running. This story explores the complexities of water management (the groundwater and surface water connections) and what it says about aging infrastructure. Also, the story has a great and all-too-real quote from the University of New Mexico’s John Fleck: “We’ve optimized entire human and natural communities around the way this aging infrastructure allows us to manipulate the flow of rivers, and we’re likely to see more and more examples where infrastructure we’ve come to depend on no longer functions the way we planned or intended.”
🚧 3/ More on aging infrastructure. Following the federal government’s disclosure of Glen Canyon Dam earlier this year, Morgan Sjogren looks at its future in Sierra Mag.
🐦 4/ Fantastic story on Wilson’s phalarope from High Country News’ Caroline Tracey.
That’s all for now. Wishing everyone a good weekend.
-Daniel