Spectral luminescence scanning (SLS) is a novel technique that uses a UV light source and line-scan camera to generate photoluminescence images of carbonate materials, such as corals. The camera in the Avaatech XRF core scanner records luminescence signals in three spectral domains of visual light, providing Red, Green and Blue (RGB) luminescence intensity data. Spectral luminescence Green/Blue ratios (G/B) of coral skeletons have previously been employed as a proxy to reconstruct river runoff. Prior G/B reconstructions have been formulated based on indirect G/B-runoff relationships (e.g. modelled discharge), as coral cores were drilled from regions where reliable long-term instrumental data were lacking,