Ref: CTALK-2019-0120

Heavy rainfall estimates from underground gravity measurements

Delobbe, L. ; Francis, O. ; Watlet, A. ; Van Camp, M.

Talk presented at EMS Annual Meeting 2019 on 2019-07-12

Abstract: Estimation of rainfall amounts produced by convective storms is challenging due to the very high spatial variabilityof such type of precipitation. In this study we explore the use of underground gravity monitoring to estimate heavyrainfall at a spatial scale of a few hundred meters.Superconducting gravimeters produce gravity measurements with a precision of 1 nm/s2at 1-minute timestep. When performed underground, these measurements are directly affected by rainfall. Water mass increase atthe ground level due to precipitation tends to reduce underground gravity. Rainfall amounts can be derived fromthese gravity variations.The superconducting gravimeters used in this study are installed in Membach (Belgium) and Walferdange(Luxembourg), 48 m and 80 m underneath the surface, respectively. The gravimeters integrate soil water in aradius of several hundred meters. The two gravimeters are located at 85 and 54 km from a C-band weatherradar located in Wideumont (Belgium). Gravimeter data at 1-min time step and radar data at 5-min time step areavailable for the 15-year observation period 2003-2017.The comparison of radar reflectivity and gravity time series shows that short-duration intense rainfall eventsproduce a rapid decrease of the underground measured gravity. Precipitation amounts derived from gravitymeasurements and from radar observations are further compared for more than 500 events with very intenseprecipitation over short durations.We show that a superconducting gravimeter is a valuable source of in-situ observations for the verificationof rainfall estimates derived from weather radars. The two main benefits are the spatial scale at which precipitationis captured and the interesting property that gravity measurements are directly influenced by water mass at groundno matter the type of precipitation: hail or rain

Keyword(s): Weather radar ; Membach ; Walferdange ; Superconducting gravimeter ; Precipitation

The record appears in these collections:
Conference Contributions & Seminars > Conference Talks > Contributed Talks
Royal Observatory of Belgium > Seismology & Gravimetry

 Record created 2019-06-18, last modified 2019-06-18