Data supporting the paper submitted to Earth's Future: "Extreme hydrometeorological events, a challenge for geodesy and seismology networks" by Van Camp, de Viron, Dassargues, Delobbe and Chanard. The data contains: -Gravity [nm/s²]: from the superconducting gravimeter (after correcting for tidal and atmospheric pressure effects), To convert it into mm water: use factor -1/0.39 [mm/nm/s²] -Seismology [counts]: from the broadband Guralp CMG-3ESP seismometer, -Rain [mm water]: data inferred from the weather radar -Flow [m³/s]: water entering the Eupen reservoir This paper contains the time series from and around the Membach station, Belgium, as recorded during the July 2021 flood of the Vesdre River. Time in second since 2021-01-01 00:00