Sharing the invisible

When the dry season grips the Mono River Basin in West Africa and surface water retreats, the true lifeline at the borderlands between Togo and Benin comes into play. It isn’t found in the riverbed, but deep below the earth.

For the many millions of rural residents across Africa, groundwater is the ultimate safety net against climate change. As the rains fail and the rivers run dry, it is the invisible aquifers below ground that keep crops alive, children in school, and communities intact.

Yet, for decades, this transboundary resource has remained largely unmeasured, and in some areas is increasingly under threat. You cannot protect what you cannot see, and you cannot sustainably manage an aquifer that crosses international borders without knowing what is happening beneath the soil of your neighbors. A transboundary aquifer can be freely pumped by one country, inadvertently lowering the water table and drying up rural community wells in another.

But unlocking this hidden and often misunderstood resource requires more than just goodwill; it requires real-world data (and more than a little on-the-ground detective work to get that data).

Under the Global Environment Facility (GEF)-funded Groundwater for aDvancing Resilience in Africa (G4DR) project, teams of hydrogeologists and local officials recently set out across the Mono River Basin (shared by Togo and Benin) and the Shire Aquifer System (shared by Malawi and Mozambique) on a critical mission: the hydro-census.

Their goal was simple on paper but daunting in practice: locate existing boreholes, assess their status, and establish the foundations for what will be the first truly cooperative, cross-border groundwater monitoring network in the continent (and possibly anywhere).

Boreholes are narrow, deep shafts drilled into the earth to reach the water table. Generally speaking, there are two main types. Most people are familiar with production wells. These are community boreholes equipped with handpumps or motorized pipes designed specifically to pull water out for drinking, sanitation, and agriculture.

However, a scientific hydro-census is primarily searching for monitoring boreholes (also known as observation wells). These are not designed to extract water; instead, they are essentially dedicated listening posts.

“While a community-dug, rural production well might only need to be 20 meters deep to reach drinking water, a monitoring borehole often needs to be drilled much deeper to accurately assess the long-term health of the entire aquifer system,”

explains Dr Girma Ebrahim, a lead hydrogeologist working on the project.

“From these monitoring boreholes, you can measure groundwater level, and in many cases temperature and electrical conductivity, which is an indicator of water salinity and by extension coastal saltwater intrusion.”

These measurements can be done manually with a dip meter, which involves dropping a probe down the borehole and unwinding a graduated tape until the probe contacts water, triggering an audio or visual alert.

Alternatively, a submersible data logger can be permanently installed (suspended on a cable) to provide continuous measurements over time which can then be downloaded for analysis (or ‘beamed’ to the cloud in the case of more advanced setups).

Prior to the G4DR teams deploying to the field, national databases suggested a healthy distribution of functional monitoring boreholes in both basins. The reality on the ground, however, revealed that approximately a third were not actually functioning, due to varying degrees of damage – leaving a sizeable dent in any hoped-for monitoring network.

Fortunately, in the Mono Basin the team determined that, given the right rehabilitation work, these non-functioning boreholes could be resorted and successfully monitored. Most sites in the Shire Aquifer, however, were completely blocked or extensively damaged rendering them beyond saving.

So faced with a lack of viable existing infrastructure, the Shire team converted their rehabilitation budget into plans for drilling new, purpose-built observation boreholes. In a vital first step for regional water diplomacy, technical teams sat down to co-design entirely new transboundary monitoring networks.

“Every GPS coordinate for a new borehole had to be discussed, scientifically validated, and jointly agreed upon to ensure both sides of the border would benefit from the data,”

Girma reflects.

Today, as drilling equipment prepares to break ground on these newly co-designed transboundary sites in the Shire, and rehabilitation work begins in the Mono, these basins are stepping out of the dark.

The project is currently engaging with stakeholders to develop formal data-sharing protocols. Because these aquifers are connected, pumping activity or pollution in one country directly impacts the groundwater availability in the neighboring country.

The current monitoring network is just the beginning – as G4DR’s Chief Technical Advisor, Dr Jonathan Lautze indicates.

“The ultimate goal over the next decade is to proactively integrate the management of both surface and groundwater – a strategy known as conjunctive management,”

he comments.

By turning the invisible into the visible, the G4DR project is proving that the deepest resilience doesn't come from the water itself, but from the communities and countries willing to adapt and manage it together.

The Groundwater for aDvancing Resilience in Africa (G4DR) project is a four-year (2024–2028) transboundary initiative enhancing regional water security through sustainable groundwater development. Operating across Pan-African, national, and local scales, it features three pilot sites: the Mono River Basin (Benin/Togo), the Shire Aquifer System (Malawi/Mozambique), and the Upper Nile Water Management Zone (Uganda). Its objective is to advance climate resilience, food security, and community well-being by coordinating the management and protection of Africa's largest underutilized water resource.

G4DR safeguards the livelihoods of rural and borderland communities by bridging high-level policy with on-the-ground realities. By co-designing transboundary monitoring networks, creating data-driven risk frameworks, and empowering women and youth, the project ensures shared aquifers are equitably managed and integrated into climate adaptation strategies.

Funded by the Global Environment Facility (GEF), G4DR is implemented by the UN Food and Agriculture Organization (FAO) and executed by the International Water Management Institute (IWMI). Key partners include the African Ministers' Council on Water (AMCOW), the International Institute for Applied Systems Analysis (IIASA), and the SADC Groundwater Management Institute (SADC-GMI).

For more information, please contact Chief Technical Advisor Jonathan Lautze (j.lautze@cgiar.org)

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