Fingerprinting sources of beach sands by grain-size, using mid-infrared spectroscopy (MIRS) and portable XRF. Implications for coastal recovery along a tsunami-struck delta coastline

•Combining MIRS-XRF and DA to fingerprint the alluvial sources of beach sands.•Optimal source fingerprinting is achieved with the medium sand fraction.•DA predictions show good agreement with simple forward modeling of sediment fluxes.•Sand provenances display affinities organized into clusters of coastline stretches.•Sand fossil stocks from former beach ridges contribute to post-tsunami beach recovery.