Balancing water and sand demands: a research agenda to support more sustainable sand harvesting from sand rivers in sub-Saharan Africa

Abstract

Sand river systems, a type of ephemeral river with shallow groundwater stored in its sandy riverbed, are increasingly gaining recognition for being nature-based water storage systems that play a pivotal role for ecosystems and rural livelihoods. However, these unique water systems are not only appreciated for their water storage and transmission; the sand is also extracted to serve the growing urban construction demands. As a result, there is increasing competition, tension and conflict about the different, often mutually-exclusive, uses of these rivers. In this paper, we call for research action as we see an urgent need to recognise the challenges and conflicts that occur and have a detrimental impact on the ecosystems and people depending on these rivers. We identify challenges and knowledge gaps, based on three case studies from sub-Saharan Africa, each with different sand harvesting histories and approaches to address these challenges. We conclude that current knowledge about the scope, intensity and impacts of sand harvesting from these shallow aquifers is minimal. Despite the regulation attempts in a few countries, monitoring and governance to establish sustainable sand harvesting and sand river conservation remain below par in all countries studied. Therefore, we call for conjunctive action to address the identified research needs, based on different actors from riparian communities, governments, academia, NGOs and the private sector. We conclude that addressing these needs is pivotal in coping with current and future challenges in different contexts to protect and benefit from these valuable river systems in the semi-arid and arid lands of sub-Saharan Africa.