## 6 Conclusions  
The analysis of 25 years of PSI measurements in the Brussels region showed that the city centre was affected by an uplift of more than 4 cm along the Senne valley. Following our model, the recharge of the deeper aquifers has been the driving force since the 1970s. The end of large-scale groundwater exploitation since the end of the industrialization of the city is responsible for the groundwater rise. This is attested by several modern (1988-2014) piezometric measurements in these aquifers as well as historical levels. From 1880 to 1970 the city centre was probably subsiding due to the drop of the pore water pressures in the Cenozoic and the Paleozoic aquifers resulting in a compaction of the rocks. The observed uplift rate in the city centre is at its maximum during the ERS and Envisat periods, and tends to reduce during TerraSAR-X and Sentinel 1. The main results of this study demonstrate also that an inelastic rebound produced by the recharge of the deep aquifers has lasted almost 45-50 years. Groundwater exploitations have increased during the industrial era (at least from 1880 to the 1960s) implying a progressive overexploitation of the shallow aquifers and the progressive use of the artesian aquifers such as the deep ones related to the Cretaceous and Paleozoic rocks. The SAR data presented here suggest that the area of Brussels is again stable at a large scale and is no longer affected by uplifting conditions. These results need to be confirmed by new Sentinel 1 SAR images over a long interval (i.e., several years).  
On the contrary, localized subsidence ground movements seem to affect the alluvial plain of the Senne River suggesting natural compaction of recent Quaternary sediments. This process was never before observed along the Senne River on ERS, Envisat and TerraSAR-X images due to the positive PS velocities associated to the aquifer recharge. Subsidence patterns in the Maelbeek, Woluwe and Senne river valleys were also highlighted. The subsidence can be related to the natural settlement of soft, young alluvial deposits, possibly intensified by the load of buildings.  
TerraSAR-X data were provided by Deutsches Zentrum fur Luft-und Raumfahrt (DLR) under the proposal GEO3185. The ERS and Envisat are provided by ESA. Sentinel 1 data were provided by the Copernicus program. Recomputed ERS 1/2 orbital data were obtained from DEOS, TUDeIt. The research is funded by the Geological Survey of Belgium and partly by the Belspo GEPATAR project.  
[PERSON] globally wrote this paper being part of his research activities at the Geological Survey of Belgium, a department of the Royal Belgian Institute of Natural Sciences. [PERSON] provided the InSAR results of ERS and TerraSAR-X and wrote the materials and methods part. [PERSON] (acting also as the PhD supervisor--official co-promotor of the PhD thesis of [PERSON]) and [PERSON] helped with the geological and hydrogeological data interpretation. [PERSON] and [PERSON] (acting also as the PhD supervisor--official promotor of the PhD thesis of [PERSON]) contributed to improve the quality of the paper. [PERSON] provided the SAR software support for processing the Sentinel 1 data.  
The authors declare no conflict of interest.