HiGrav – High-Resolution Gravity Fields for Better Flood Forecasting

Floods are among the most damaging natural hazards worldwide, and their impacts are intensifying under changing climate conditions. A key challenge in flood forecasting is understanding how much water is already stored in a catchment, in soils, aquifers, snowpacks and rivers, before an extreme rainfall event occurs. The HiGrav project addresses this challenge by exploiting observations from Earth-observing gravity satellites to better characterize large-scale hydrological conditions.

Satellite gravimetry from the GRACE and GRACE-FO missions provides a unique, observation-based view of terrestrial water storage by measuring changes in Earth’s gravity field caused by mass redistribution. However, current gravity-based products are typically available at monthly resolution and coarse spatial scales, which limits their applicability for flood monitoring and early warning. HiGrav project aims to overcome these limitations by substantially increasing both the temporal and spatial resolution of gravity-based water storage information.

HiGrav develops a new framework to derive daily gravity field solutions from GRACE and GRACE-FO observations and to translate them into high-resolution terrestrial water storage anomalies. The project aims to generate globally consistent daily water storage maps at spatial scales relevant for hydrological processes and investigates their value for flood monitoring and forecasting at global and regional scales.

A wetness index is developed to characterize pre-event hydrological conditions and flood potential, and its value is assessed using historical flood records, hydrological observations, and forecasting experiments. By integrating satellite gravimetry, machine learning, and hydrological modelling, HiGrav aims to establish gravity-based water storage for flood monitoring and early-warning applications.