The potential of sand dam road crossings

In many African dryland regions, culverts are built under low-volume rural road river crossings. The capacity of culverts is often inadequate to accommodate the peak floods and, over time, sedimentation reduces this capacity further. As a result, culverts are vulnerable to being washed away. Sand dams that incorporate a ford are an alternative to culverts and offer significant benefits. Correctly designed sand dams manage flood flows and are a robust, cost-effective alternative. Among additional benefits, sand dams recharge the aquifer, reduce downstream flood risks and provide a reliable, year-round water supply in water-scarce environments. This paper documents a case study from Kenya where a sand dam acts as both a road crossing and the source for a water pipeline. The paper describes the principles for siting, design and construction of sand dam road crossings, where this approach is appropriate and the barriers and enablers to wider adoption.