Mangroves play a critical role in mitigating wave forces and preventing beach erosion by trapping sand behind their vegetation. However, accurately simulating their complex interactions with waves and sediment transport is computationally demanding due to the fine grid resolution required to replicate vegetation. This study employs a low-cost computational method that models mangroves using porosity and the Dupuit-Forchheimer law to analyze the relationship between wave fields and sediment transport. Using the coupled model CADMAS-STR-STM, numerical simulations were conducted to investigate topographic changes under varying resistance coefficients. Experimental results demonstrated counterclockwise flows and shoreward velocities behind mangroves, leading to reduced erosion and increased deposition in certain areas. Numerical simulations qualitatively reproduced these patterns under different parameter combinations. While further refinement is needed, these findings suggest the proposed method's potential to predict sediment transport processes in mangrove environments.