Surface water extent is observed using passive microwave remote sensing (AMSR2 and GPM sensors). When surface water increases significantly (anomalies with probability of less than 99.5%), the system flags it as a flood. Time series are calculated in more than 10000 monitoring areas, along with small scale flood maps and animations.

GFDS currently monitors around 10000 areas, defined in collaboration with partners. For these areas, the flood signal is further processed to generate time series, flood maps and flood animations.

The purpose is to identify and measure floods with potential humanitarian consequences after they occur.