Optimizing the contributions of sand dam water storage through understanding their spatiotemporal variability: Evidence from the Shashe catchment, Limpopo, River Basin

Shashe catchment, Limpopo River basin, Zimbabwe Sand dams, small structures built in ephemeral rivers to capture and store river flows in the sand, provide an important water source for rural communities that lack formal infrastructure. While their potential benefits are increasingly recognized, the spatiotemporal variability in the water they store remains unstudied. This knowledge gap constrains evidence-driven planning for sand dam development and limits the incorporation of sand dams into an integrated storage framework, a key approach to enhance resilience by satisfying storage needs from a diverse range of sources. To address this gap, this study uses in situ data to report on the spatiotemporal variability of water storage in sand dams in the Shashe catchment of the Limpopo River Basin. Five sand dams and two natural (i.e., undammed) sites were monitored weekly for water level fluctuations from January to December 2024. Results indicate that all sand dams greatly improve water availability during the dry season compared to natural sites. Sand dams built on larger rivers are nonetheless more effective at maintaining water supply throughout the dry season. Seepage is identified as the primary pathway for water loss from the sand dams. To unlock the full potential of sand dams, planners should actively consider siting parameters, namely the river width, sediment accumulation thickness, sand accumulation area, and catchment area. Utilizing these criteria to inform planning can enhance the contribution and impact of sand dams, building more resilient and sustainable water systems. Weekly water storage volumes in sand dams and natural (i.e., undammed) sites in the Shashe catchment • Weekly water level fluctuations were monitored at five sand dams and two natural sites from January to December 2024. • Sand dams greatly improve water availability during the dry season compared to natural sites. • Sand dams built on larger rivers are more effective at maintaining water supply throughout the dry season. • Seepage is identified as the primary pathway for water loss from the sand dams. • Despite seepage losses, sand dams provide essential water storage for rural communities.