Publication Date:
2023-06-26
Description:
We analyze vertical ground displacement time-series data from GNSS stations in the Po river basin, Italy, to measure deformation signals associated with the drought occurring since 2021 and to estimate the quantities and spatial distribution of water storage loss. We use a regularization model, based on L1-norm, to reconstruct the long-term temporal evolution of vertical ground displacement trends. Next, we performed a principal component analysis (PCA) to extract a spatially consistent signal in ground displacements. The first principal component is well-correlated with trend changes of the Po river level, indicating that common long-term variations in vertical ground displacements are driven by the hydrology of the area. Using the PCA results, we estimate variations in equivalent water height (EWH) and find that the GNSS uplift of up to 7 mm is caused by an EWH decrease of some decimeters. The results are compared with GLDAS and GRACE models: while the temporal evolution of the three products, when averaged over the study area, is similar, the spatial distributions are different. This is likely due to the fact that GLDAS only takes surface water into account, and GRACE has a too-coarse spatio-temporal resolution. Our results show that multi-year changes in water storage can be effectively monitored both in terms of temporal evolution and spatial distribution using space geodetic measurements, such as GNSS. This approach eliminates the need to rely solely on large-scale models or satellite measurements, which cannot reach the spatial resolution required at the scale of river basins such as the Po.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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