Ahmed, M.T.T.; Sato, S., and Tajima, Y., 2014. Quantitative estimation of longshore sediment transport based on thermoluminescence: two case studies around Tenryu and Nile River mouths.
Longshore sediment transport (LST) is one of the key factors determining coastal deformation. Appropriate understanding of LST is thus essential to sustain coastal management and propose efficient countermeasures. However, it is quite difficult to quantify LST where detailed information of waves and bathymetries is not available. This study provides a novel methodology for quantitative estimation of LST by utilizing the residual thermoluminescence (TL) properties of feldspar grains. A newly proposed TL-based system estimates LST as a function of alongshore distributions of TL and dominant wave heights at the study sites. This study first analyzed and developed the TL-based bleaching curves due to sun exposure of the 180–300 μm fraction of feldspar grains from three different regions: Egypt, Japan, and Sri Lanka. On the basis of the obtained bleaching curves, the spatial distribution of TL along the coast was estimated, and the alongshore slope of TL decay was compared with the locally estimated average longshore current velocity, mixing sand layers, and moving sand volume, all of which were subsequently linked to LST. The newly proposed methodology was applied to two coastal areas around the Tenryu River and Nile River mouths, and it was found that the proposed methodology is capable of estimating directions and amount of LST around river mouths where sand with high TL is discharged continuously.