Reno, Nev. (July 17, 2024) – Groundwater-dependent ecosystems provide crucial support to life in arid regions by acting as water reserves during droughts. As climate change and human activities deplete groundwater levels globally, there is an urgent need for better data on these ecosystems' locations. A new study published in Nature on July 17 addresses this gap by mapping groundwater-dependent ecosystems in dryland regions worldwide, assessing their protection status, and examining their overlap with human communities.
The research, led by scientists from The Nature Conservancy and the Desert Research Institute (DRI), represents the first global-scale mapping of these ecosystems. Researchers from universities, non-profit organizations, and institutions across seven countries collaborated on this effort. Findings indicate that 53% of these ecosystems are in areas experiencing groundwater depletion, while only 21% are located in protected lands or regions with conservation policies.
“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,” says Melissa Rohde, Ph.D., ecohydrologist and environmental consultant who is the lead author of the study. Rohde conducted this research as part of her doctoral dissertation at the State University of New York’s College of Environmental Science and Forestry and through her work at The Nature Conservancy.
Groundwater-dependent ecosystems vary widely from desert springs to coastal wetlands. These areas are often biodiversity hotspots but face increasing threats from climate change and human exploitation. The lack of data prompted Rohde's mapping initiative when colleagues at The Nature Conservancy encountered challenges in conserving these ecosystems due to insufficient information.
Using six years of data from NASA’s Landsat satellite along with over 30 thousand confirmed locations of groundwater-dependent ecosystems, researchers trained a computer model to identify these areas based on satellite imagery indicators such as leaf water content and land temperatures.
“Our team at DRI had been using satellite remote sensing data to locate and characterize changes in groundwater-dependent ecosystems across the western US for many years, and this was the perfect opportunity to expand this work globally,” says Christine Albano, Ph.D., ecohydrologist at DRI.
The analysis revealed that groundwater-supported ecosystems remain greener and cooler during dry seasons—a characteristic detectable via satellite imagery. This enabled researchers to create a global map showing where such ecosystems existed between 2015-2020 with an estimated accuracy rate of around 87%.
“The intention of our map is that it be used as a starting point,” Rohde says. “It provides essential information on where they are likely located and most at risk of groundwater depletion so that we can advance the protection of these biologically diverse ecosystems.”
The map highlights more intact ecosystems in Central Asia, Africa's Sahel region, and South America compared to depleted areas like North America and Australia where extensive agricultural irrigation occurs.
To underscore the role of these ecosystems in supporting rural livelihoods, the study focused on Africa's Greater Sahel region where conflict hotspots coincide with numerous groundwater-dependent ecosystem locations. Climate change exacerbates food insecurity here leading to expanded crop cultivation into pastoral lands.
“These ecosystems have a direct impact on the rural livelihoods of pastoralists,” Rohde notes. “There needs to be creative solutions to preserving these ecosystems depending on regional contexts.”
Despite findings that 21% of such ecosystems are under some level of protection; effective legislation remains limited without understanding how groundwater supports them fully.
“We need to acknowledge that groundwater is critical for many ecosystems,” states Rohde. “If we want to achieve our global biodiversity goals alongside climate goals then connecting dots between groundwater management practices becomes imperative.”
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More information: The full study "Groundwater-dependent ecosystem map exposes global dryland protection needs" is available from Nature athttps://www.nature.com/articles/s41586-024-07702-8
For an interactive version visit https://codefornature.projects.earthengine.app/view/global-gde
Study authors include: Melissa M. Rohde et al.
About DRI
We are Nevada’s non-profit research institute founded in 1959 focusing on impactful science.
Visit www.dri.edu for more details.
About The Nature Conservancy
A global conservation organization dedicated towards sustainable land-water management working across 72 countries.
Visit www.nature.org or follow @nature_press on Twitter for more details.
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