Construction planning in coastal urban areas requires a detailed understanding of water table dynamics, particularly when excavation is projected below the phreatic surface. This study presents the simulation of six critical scenarios using independent numerical models developed with MODFLOW 6 and the ModelMuse interface. These scenarios correspond to six dates between November 2023 and April 2024, selected for exhibiting astronomical tide events with maximum and minimum levels occurring within a 24-hour window—conditions considered critical for excavation and dewatering processes.

Each model was calibrated using three piezometric observations per day (09:00, 12:00, and 15:00 hours), resulting in a total of 18 field records. The comparison between simulated and observed values produced low error metrics: root mean square errors (RMSE) ranged from 0.014 to 0.087 meters and mean absolute errors (MAE) ranged from 0.012 to 0.075 meters. While these differences are small—in the order of centimeters—they are consistent with the short evaluation period and the low day-to-day variability observed during calibration. However, during the full six-month study period, recorded groundwater levels ranged from –0.10 to 0.53 meters above sea level. Understanding the dynamics of the water table across this range is essential for anticipating construction challenges and designing appropriate mitigation strategies.

Taking the 18 observations as representative, the overall model performance yielded an RMSE of 0.056 m and an MAE of 0.049 m, supporting the use of numerical simulation as a reliable planning tool for construction projects below the water table in coastal environments. Moreover, the integration of numerical modeling in early project stages promotes more sustainable construction practices by reducing environmental impacts and enabling better-informed decisions.