Section 1 of this report provides context on the role of mangroves, as a unique ecosystem, and their benefits to people. It also outlines why sediment supply is important for mangrove sustainability, the impacts of a diminishing sediment supply, and why one should consider sediment when undertaking mangrove conservation and restoration. Section 2 sets the objectives and frame of the rapid assessment tool. Section 3 presents method and guidance to understand and assess key processes, the impact of human interventions and how to measure this impact on sediment flows and deposition, while taking into account the state of relevant governance and policy frameworks at four spatial scales of analysis interlinked by sediment flow connectivity: (1) river basin scale, (2) delta scale, (3) coastal scale, and (4) site scale. Section 4 explains how to conduct a rapid assessment for non-experts when data is readily available – even if it is limited. Section 5 provides concluding remarks on the future of mangroves in the context of climate change and increasing anthropogenic pressures. Further guidance on how to use the tool is provided in the annex.