The primary aim of this study is to determine the ellipsoidal heights of the Lowest and Highest Astronomical Tides (LAT) and (HAT) in Alexandria Western Harbor (AWH), as these measurements are of significant importance in the field of cartography. In order to get precise calculations of these elevations, it is important to obtain observed sea level data spanning a period of 18.6 years, which corresponds to a nodal cycle. To address the lack of available sea level data in the study area, the researchers utilized modeled sea level data obtained from a hydrodynamic model known as the Delft-3D model. This model provided a 19 year dataset, which was employed as a substitute to overcome the data scarcity issue. The levels known as LAT (Lowest Astronomical Tide) and HAT (Highest Astronomical Tide) were selected as the established benchmarks for denoting the depths and heights on nautical charts, respectively. The validation of the model involved the utilization of observed sea level measurements obtained from tide gauges located within the area of interest, namely the AWH. A geodetic control point located within AWH was established and accurately referenced to the most recent geodetic reference frame, ITRF-2014. Subsequently, it was transported using leveling techniques to the zero level of the tide gauge in order to determine sea level realization and facilitate chart datum calculations. Based on the concurrent examination of observed and modeled sea level datasets at identical time intervals, it was deduced that the primary driver of sea level variations is tidal energy, accounting for 54% (in the case of observed data) and 75% (in the case of modeled data) of the overall power contributing to sea-level fluctuations. The elevated percentages observed can be attributed to the presence of 13 notable tidal constituents, with the solar annual (Sa), lunar semi-diurnal (M2), solar semi-diurnal (S2), and solar semi-annual (Ssa) tidal constituents being the most influential. The aforementioned results demonstrate the significance of seasonal patterns influenced by yearly weather fluctuations, which consequently impact fluctuations in sea levels within the region. Furthermore, the tidal regime seen in AWH is classified as semi-diurnal, characterized by a ratio of 0.25. The root mean square error (RMSE) of amplitudes between the modeled and observed datasets varied from 0.005 to 0.012 m, suggesting that the modeling findings reasonably simulate the heights. The sea level data spanning a period of 19 years, from January 1, 1996, to November 30, 2015, exhibited a positive linear trend, indicating a rise in sea level at a rate of 3.4 mm/year. This finding is consistent with previously determined rates of sea level rise. In order to perform tidal datum calculations, the ellipsoidal heights of the Lowest Astronomical Tide (LAT) and Highest Astronomical Tide (HAT) were revised, taking into account a safety margin of ±10 cm. The recommended values for LAT and HAT, with respect to the International Terrestrial Reference Frame of 2014 (ITRF-2014), are 14.29 and 15.23 m, respectively. Alternatively, when referenced to the World Geodetic System of 1984 (WGS-84), the suggested values for LAT and HAT are 14.36 and 15.20 m, respectively.