What can long-term<i>in situ</i>monitoring data tell us about our coastlines?

<jats:title>Abstract</jats:title><jats:p>Long-term<jats:italic>in situ</jats:italic>monitoring of beach morphology is indispensable for capturing the processes of foreshore morphological changes, and thus many beach monitoring campaigns have been conducted globally. Here, we review the various foreshore beach processes attributable to cross-shore sediment transport, which have been elucidated through long-term beach monitoring. Historical<jats:italic>in situ</jats:italic>beach monitoring has revealed many daily–annual-scale cyclic foreshore beach morphological changes and shoreline changes; however, many shorter- and longer-term processes remain unresolved, for example, the short-term response to tidal fluctuations and the long-term response to sea level rise. The cost per area surveyed of state-of-the-art equipment will gradually decrease over time, and the accuracy, resolution, and volume of information obtained from the monitoring methods, which are still in the early stages of development, will improve as research progresses. Continued long-term monitoring and acquisition of previously unmeasured monitoring data through the development of monitoring methods are expected to help elucidate unresolved beach processes.</jats:p>