Using CYGNSS Data to Map Flood Inundation during the 2021 Extreme Precipitation in Henan Province, China

On 20 July 2021, parts of China’s Henan Province received the highest precipitation levels ever recorded in region. Floods caused by heavy rainfall resulted hundreds casualties and tens billions dollars’ worth property loss. Due to highly dynamic nature flood disasters, rapid timely spatial monitoring is conducive for early disaster prevention, mid-term relief, post-disaster reconstruction. However, existing remote sensing satellites cannot provide high-resolution results. Seeing as spaceborne global navigation satellite system-reflectometry (GNSS-R) can observe Earth’s surface with high temporal resolutions, it expected a new solution problem hazards. Here, using Cyclone Global Navigation Satellite System (CYGNSS) L1 data, we first counted various signal-to-noise ratios corresponding reflectivity features Province. Subsequently, analyzed changes delay-Doppler map CYGNSS when observed area was submerged not submerged. Finally, determined affected extreme threshold detection method. The results demonstrated that range retrieved agreed Soil Moisture Active Passive (SMAP) mission data measured Precipitation Measurement meteorological stations. Compared SMAP results, those obtained have higher resolution monitor areas floods over shorter period.