We study vertical ground displacement time-series from GNSS stations in the Po river basin to measure deformation signals associated with the severe drought occurring since 2021 and estimate the spatial distribution of water loss. The detection of vertical ground displacement trend changes allows us to extract a spatially correlated signal that follows the Po level trend changes and SPEI-12 drought index. GNSS stations in the basin mostly underwent uplift, up to 7 mm, since 2021, which corresponds to ~80 Gtons of water loss. Compared to GLDAS and GRACE, the GNSS results show a similar temporal evolution of water content, but a different spatial distribution. Our study indicates that using dense GNSS networks is an effective way to monitor long-term changes in water storage even in small water basins and serve as a reliable indicator of drought severity.