Ridge to reef modelling for use within land–sea planning under data‐limited conditions

Soil erosion associated with land‐use change is considered one of the greatest human threats to coral reef ecosystems globally. To account for sediment runoff in land–sea planning, spatially and temporally dynamic models are needed that predict where soil loss is occurring, in addition to where sediments are travelling and settling in coastal marine areas. This assessment is particularly difficult given the complex three‐dimensional movement of sediment in water bodies. This study assessed the vulnerability of key marine resources to sedimentation in Raja Ampat, Indonesia, by developing a coupled terrestrial and marine model that relied primarily on global datasets. The model predicted the quantities of sediment at river mouths, and the spatial extent over where this sediment disperses in the ocean. In total, 1850 km 2 of coral reefs, marine protected areas, dive sites, pearl farms, and other benthic habitats in Raja Ampat were found within sediment plumes with varying degrees of impact. Two hypothetical land‐use scenarios were created to illustrate the sensitivity of sedimentation on marine resources to development, and to compare future alternative management scenarios. The model provides a powerful tool for planners to understand how land management, and land‐use change might affect marine resources, particularly in data‐limited regions.