Water for sustainable development: examining the water–energy–food–society nexus (SDG 17)

SDG 17 underscores the pivotal and interconnected role of water, including its energy implications, in addressing challenges related to human well-being and sustainable development. Solar water pumps (SWPs) offer an important technological innovation exemplifying this water–energy–food–society nexus. As a comparatively new and eco-friendly approach to irrigation, SWPs have the potential to substantially benefit millions of smallholder farmers in sub-Saharan Africa (SSA). With costs for solar products steadily reducing, the small-scale SWP market is expected to grow in sales and expand into new territories. Overall, the region’s groundwater resources are known to be greatly underutilized and hence enable greater SWP adoption. This study assesses the possible risks to groundwater resources from SWP expansion to the year 2030. The current market environment is extremely heterogeneous across regions and countries. It is conservatively estimated that up to 10,000 units are sold each year, with the strongest markets found in East Africa. Around 100,000 SWP units are estimated to be in operation. For projected rates of annual growth spanning from 6% to 18%, along with intentionally high estimates of groundwater pumping, the upper limit on the quantity of available groundwater pumped by small SWP development to 2030 would vary from 0.4% to 0.6% at the SSA scale. Values in the regions vary from a low of <0.1% for Central Africa through to a high of 1.6%–2.1% for Southern Africa. Specific countries may generally support additional SWPs ranging from tens of thousands up to millions of units without negatively impacting on groundwater availability. Countries characterized by greater recharge and lower current groundwater use can accommodate greater numbers of SWP systems. Short-term threats to the availability of groundwater are assessed to be low over the short and medium terms. Over the long term, risks to groundwater may be greater than evaluated in this study should SWP growth rates exceed the projected range or if improvements in technology allow for stronger, small-capacity pumps to flood the market. To address long-term groundwater management challenges, key action areas have been defined that recognize the diverse conditions across the regions.