Flood Risk reduction using protective and boulder walls: A review with special reference to Afghanistan

Afghanistan faces progressively regular and severe floods that cause substantial loss of life, destroy the infrastructure, and interrupt livings. Structural mitigation measures mainly protective walls built from locally available boulders offer practical, low-cost solutions in this resource-constrained context. This review synthesizes national and international literature on flood risk reduction using protective walls, with special importance on boulder walls in Afghanistan's flood-prone provinces. We assess design considerations, efficiency, environmental impacts, and implementation challenges. Key results show that while boulder walls provide cost-effective, community-driven flood mitigation, they require technical design support and integration with non-structural measures such as early warning systems and land-use planning to attain sustainable risk reduction. This review offers evidence-based guidance for practitioners, policymakers, and communities working to improve flood resilience across Afghanistan.