# 6. Policy implications

Irrigation has shaped civilizations across history and continues to present much potential in regions such as sub-Saharan Africa (SSA), where a small fraction of land is irrigated and even less by groundwater (Rodella, Zaveri and Bertone, 2023). Irrigation can significantly increase production, especially in arid and semi-arid regions (Kukal and Irmak, 2019, Fernández-Cirelli et al., 2009). In the case of SSA, shallow groundwater irrigation has the potential to be game-changing, protecting farmers from weather shocks and helping countries of the region tackle food insecurity (Gowing et al., 2016; Rodella, Zaveri and Bertone, 2023).

With stunting affecting one in four children in the SSA region, the question is not whether to expend groundwater irrigation, knowing that access to shallow groundwater can decrease the chances of childhood stunting by 20% for rural children in this region by protecting agricultural productivity (Rodella, Zaveri and Bertone, 2023), but how to do so sustainably, minimizing unintended consequences (Balasubramanya et al., 2024). Lessons from other regions, such as South Asia and the Middle East, can guide these efforts.

The results presented in our paper provide novel insights into some of those risks as they relate to groundwater-dependent ecosystems. They are threatening GDEs and present three main issues. First, as GDEs are poorly mapped or monitored, their total value and benefits need to be better understood and measured. Yet, with slight variation in groundwater level needed, there is little chance of restoration when they are gone due to their fragile nature, particularly in dryland areas (Rohde et al., 2017). Second, GDEs are important for the livelihoods of populations in rural areas that are typically more vulnerable. An unfettered provision of solar pumping could lead to a deterioration of GDEs on which pastoralists rely for their cattle while also expanding agricultural land to areas previously used for transhumance and grazing, heightening tensions between farmers and pastoralists (Rodella, Zaveri and Bertone, 2023). Third, beyond their importance for wildlife – including for migratory birds – GDEs play an essential role in carbon storage (Mendonça et al. 2017). Countries seeking to reduce their emission by switching groundwater pumping to solar, owe to consider the carbon impacts of compromising the role GDEs play as carbon sink.

For those reasons, the results highlight the necessity for policymakers and development partners to collaborate upstream on largescale solar energy deployment in regions with high irrigation potential, such as SSA, that will facilitate easier and cheaper access to much-needed solar pumping irrigation but require enforceable policy and regulation to protect against unintended consequences, such as the deterioration or destruction of GDEs. Our analysis also highlights the need for more data on GDEs from location to the services they provide to people and the environment to monitor better their health and address situations of poor groundwater management that could threaten their existence. The proper monitoring of GDEs can thus be an efficient strategy to contribute early warning information on the mismanagement of groundwater resource and help prevent or remedy impacts.

# 7. Conclusion

We proposed an analytical hierarchy process to evaluate the risk posed to groundwater dependent ecosystems (GDEs) by an uncontrolled expansion of access to groundwater through photovoltaic pumping in sub-Saharan Africa. More specifically, we evaluated the risk of over exploitation of groundwater resources which could endanger GDEs, and we considered the following input data: global horizontal irradiance, renewable groundwater resources, groundwater storage, population density, static water level and aquifer transmissivity. We found that numerous GDEs in southern and eastern Africa have a higher risk of over exploitation, especially in South Africa and Namibia. On the opposite, we found that GDEs in the regions of Gabon, Congo and southern Nigeria are less at risk. Additionally, by comparing our results with the number of people relying on an unimproved water source in 2017, we highlighted regions like southern Nigeria and South Sudan that could be prioritized for investments in new photovoltaic water pumping systems (PVWPS) because of the higher groundwater development need and the lower risk posed by photovoltaic pumping to GDEs. On the opposite, in other regions, like in Namibia and South Africa, where the groundwater development need is lower while the risk posed by PVWPS to GDEs is higher, investments should be wisely targeted, and a very close monitoring of groundwater resources will be required.

Despite the limitations (see Section 5), the results of this study are important in highlighting some of the unintended consequences that could result from a scaling up of photovoltaic pumping without the adequate safeguards in place to assess the potential impacts on GDEs. The findings can help policymakers and implementing ministries and agencies integrate in their development planning the potential areas where the development of PVWPS could be prioritized and where it must be more carefully monitored to ensure a sustainable use of the groundwater resources and a reduced impact on GDEs.

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