Groundwater is key to protecting global ecosystems

Often referred to as “blue gold,” groundwater is our most vital freshwater resource. A hidden treasure beneath our feet, it serves as a crucial natural capital asset essential for meeting human water needs. Remarkably, groundwater accounts for nearly half of the water withdrawn for domestic use worldwide and supports about 43% of all irrigation, nourishing 38% of the planet’s irrigated farmland.

Less well known is that groundwater sustains a broad range of ecosystems critical to livelihoods, especially in climate frontier areas. This is because when hidden water tables meet the Earth’s surface, life can thrive even in the driest locations. Offering refuge during times of drought, groundwater acts like a water savings account that can support ecosystems with the moisture required to survive, even as precipitation dwindles Such ecosystems can range from desert springs to mountain meadows and streams, to coastal wetlands and forests. Often, they are hot spots for biological diversity worldwide supporting rare and endemic species. They also remain essential lifelines for rural communities, especially pastoralists, who depend on the vitality of these ecosystems. 

Now, new data at the global and regional level using machine-learning algorithms and a wide range of archival and local sources is bringing these ecosystems out of the shadows and into the spotlight. A recent study used 30,000 data points of confirmed groundwater-dependent ecosystem locations to train a computer model to identify them at scale based on satellite data. This novel machine learning–enhanced dataset reveals that nearly 60% of groundwater-dependent ecosystems co-exist with pastoral lands, providing critical services for both wildlife and livestock. A World Bank database highlights the diversity of these ecosystems and their importance to rural communities in Sub-Saharan Africa. With support from the Global Water Security & Sanitation Partnership (GWSP), the database compiled various sources reflecting local and academic knowledge to identify more than 250 ecosystems reliant on groundwater (Map 1). 

Not only are these ecosystems critical to livelihoods but they also serve as a crucial insurance against weather variability in some of the poorest areas (Map 2).

Moreover, their carbon-capturing abilities are significant, making them important in the fight against climate change. Worldwide, perennial lakes, which are largely fed by groundwater, absorb approximately 0.33 billion tons of carbon dioxide annually, which is about 1% of current global emissions.

Despite their importance, and the services they provide, groundwater-dependent ecosystems are under pressure due to conflict and unfettered groundwater exploitation. For instance, tensions over water and land between pastoralists and farmers are expected to heighten as climate change is exacerbating food insecurity and resulting in expanded crop cultivation into previously pastoral lands. These ecosystems are thus at the crossroads of conflict and fragility hotspots. In the greater Sahel region, four well-known conflict hotspots (the Liptako-Gourma region at the borders of Mali, Burkina Faso, and Niger; the Lake Chad Basin at the borders of Chad, South Niger, Northern Nigeria, and Cameroon; the Darfur region at the borders of Sudan, South Sudan, Chad, and the Central African Republic; and the South Kordofan region between Sudan and South Sudan) have a high prevalence of groundwater-dependent ecosystems, which support local livelihoods and exist at the convergence of forced migration pathways (Map 3).

Groundwater depletion is another threat. This is because these ecosystems are sensitive to small variations in the groundwater table. In areas where unchecked pumping from wells causes groundwater tables to decline, once-thriving ecosystems can wither and die. Globally, 53% of the mapped groundwater-dependent ecosystems exist within regions exhibiting declining groundwater trends, but only 21% exist on protected lands or regions with policies in place for their protection. 

Well-meaning policies that encourage groundwater exploitation (e.g., solar irrigation)  too can inadvertently jeopardize these ecosystems. Estimates suggest that uncontrolled expansion of solar pumping in Sub-Saharan Africa could pose a risk to most groundwater-dependent ecosystems and, by extension, to the people and biodiversity that rely on them (Map 4). 

This underscores the need to prioritize the development of solar irrigation projects more carefully to ensure sustainable use of groundwater resources and a reduced impact on ecosystems. Integrated approaches to regulation and management across scales can guide sustainable pumping practices, ensuring that solar irrigation contributes to poverty alleviation without causing long-term harm. 

Ultimately, a better understanding of the interdependencies between groundwater-dependent ecosystems, climate change, rural livelihoods, food security, and social stability as part of integrated policies and programmatic decisions will be essential to reduce tradeoffs. The first step in doing so is understanding the location and extent of ecosystems, and their level of dependency on groundwater. Recent advances in machine learning and cloud computing are beginning to fill this critical knowledge gap and can serve as a useful starting point for ground-truthing and further characterizing these ecosystems at local scales. 

As the global community ramps up actions and finance for climate and biodiversity goals, it is crucial not to overlook these ecosystems and to recognize the pivotal role of groundwater in protecting them to achieve these global objectives.