# 1. Introduction

Expanding access to electricity and water are key development priorities, closely related in the regions where access gaps are most pronounced, such as in the case of Sub-Saharan Africa (SSA). The World Bank estimates that currently, 600 million people in SSA lack access to electricity, creating significant barriers to health care, education, productivity, digital inclusivity, and ultimately job creation (IEA, IRENA, UNSD, World Bank, WHO., 2024). Those barriers are compounded by a lack of access to clean water: 400 million people in SSA lack access to safely managed drinking water services (UNICEF, WHO, 2022). Progress in photovoltaic technologies has enabled a lowering of costs (Chandel et al., 2015; Global Solar Atlas, 2024) that can be a game changer in expanding access. Multilateral development partners such as the World Bank and the African Development Bank Group are partnering to provide at least 300 million people in Africa with electricity access by 2030. The expansion of photovoltaic energy at scale will also enable an expansion of solar pumping for irrigation.

This is promising for SSA where less than 5 percent of agricultural land is irrigated, and less than 7 percent of irrigated lands uses groundwater (Rodella, Zaveri and Bertone, 2023). This could also present challenges in terms of impacts on groundwater-dependent ecosystems (GDEs) and overexploitation if access to groundwater resources is not appropriately controlled, a scenario welldocumented in regions such as South Asia and the Middle East (Lezzaik et al., 2018; Mukherjee, 2018).

There is growing recognition of the importance of those GDEs, from their socio-economic to their environmental value, including for carbon storage (Esteban and Dinar, 2016; Mendonça et al. 2017; Murray et al., 2003, 2006; Rohde et al., 2024). For instance, Mendonça et al. (2017) estimate that perennial lakes, mainly GDEs, trap some 0.33 billion tons of CO2 per year, corresponding to about 1% of the present global CO2 emissions.

GDEs play a crucial role in supporting the livelihoods of some of the most vulnerable populations in Sub-Saharan Africa, such as pastoralists (Rohde et al., 2024). The role of GDEs can often be indirect, for instance, through the hydraulic lift provided by certain tree species. However, GDEs are not consistently identified and mapped on a large scale, especially in developing countries. This data gap is significant, as GDEs, particularly in arid regions, are highly susceptible to even minor fluctuations in groundwater levels, which can jeopardize their survival.

A new World Bank database of GDEs in Sub-Saharan Africa shows their diversity and importance to people living in poverty (Rodella, Zaveri and Bertone, 2023). The database was compiled using a wide range of sources reflecting local and academic knowledge and identifies more than 200 GDEs across four main geographic types—inland surface waters (riverine, lacustrine, and wetland ecosystems); coastal and marine ecosystems (coastal and near-shore marine ecosystems), terrestrial springs (near spring and springs influenced zone ecosystems; includes oases); and terrestrial vegetation (sparse vegetation ecosystems and forests and woodlands ecosystems).

This dataset allows for novel analysis of the potential impacts of intervention affecting groundwater directly and indirectly. For instance, water extraction from aquifers by pumping systems can lead to the overexploitation of groundwater resources and a decrease in groundwater storage, which can, in turn, cause a loss of discharge from groundwater to wetlands, springs, streams/rivers, or coastal areas (McCallum et al., 2013). In addition, a decline in groundwater storage can lead to a decrease in the water table (Wada et al., 2010), rendering groundwater inaccessible to terrestrial vegetation (Barron et al., 2014).

To the authors’ knowledge, this is the first paper looking at the potential impacts of the extension of photovoltaic water pumping systems (PVWPS) on GDEs. Even though several articles studied the suitability of photovoltaic water pumping systems (PVWPS) in different regions of sub-Saharan Africa (e.g., Gebrezgabher et al., 2021; Schmitter et al., 2018; Soenen et al., 2021; Xie et al., 2021), no article has investigated the risk posed to GDEs by the uncontrolled access to groundwater through photovoltaic water pumping across the continent. The potential to scale up shallow groundwater irrigation in the SSA region is undeniable and could be a game changer for poverty, food security, and climate adaptation (Rodella, Zaveri and Bertone, 2023). However, the analysis seeks to illuminate the unintended consequences of unfettered access and highlight the need for preventive measures to be in place prior to scaling up photovoltaic pumping.

In this article, we use the Analytic Hierarchy Process (AHP) to map the risk posed to sub-Saharan GDEs by an uncontrolled expansion of access to groundwater through photovoltaic pumping. More specifically, we evaluate the risk of over-exploitation for GDEs using mapped data on groundwater, irradiance, population, and GDEs. Section 2 details the datasets used in our analysis.

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