Recession analysis of the rear seabed topography due to excavation of marine sand based on the concept of equi-wave phase potential.

Globally, increasing coastal erosion-including background erosion due to rising sea levels-has become a serious environmental concern. One common mitigation strategy is the artificial supply of sand to the coast through marine sand mining (MSM). However, to ensure its effectiveness, there is an urgent need for corresponding erosion assessments. This study introduces the concept of equi-wave phase potential (EWPP) and proposes a methodology for deriving both analytical and numerical schemes to assess beach erosion resulting from MSM. EWPP governs the isobaths of seabed topography formed by sediment transport, drawing a physical analogy to the potential energy influenced by Earth's gravity. The key advantage of EWPP is that locations sharing the same potential will ultimately exhibit identical seabed depths. Using this concept, the study derives analytical and numerical solutions to predict changes in shoreline and isobath lines behind the sand mining zone. The numerical results align well with the analytical predictions, particularly highlighting the influence of trench length on shoreline and terrain changes. A graphical tool based on the EWPP analytical solution is also presented, offering preliminary guidance for coastal stability assessments in marine mining projects. Overall, the findings are significant, as they suggest that the extent of beach erosion can be proactively managed by adjusting key variables in response to fixed mining conditions.