Nowadays, studies investigating variations in Total Water Storage (TWS) have gained significant recognition through the analysis of the Global Navigation Satellite System (GNSS) vertical coordinate time series. This study focuses on the island of Haiti. The vertical loading displacements caused by TWS are calculated using the Global Land Data Assimilation (GLDAS) hydrological data model. A comparison between the annual signals of the hydrological model and GNSS data from 32 stations reveals the presence of the TWS signal in the GNSS time series. Despite the island of Haiti exhibiting a relatively small GNSS signal, the correction for hydrological effects computed with GLDAS results in a reduction of the Root-Mean-Square (RMS) scatter of the GNSS time series vertical displacement for 62.5% of the stations. The station with the most notable improvement shows a significant 50% reduction in RMS, along with a correlation coefficient of 0.88 between the GNSS and hydrological displacements.