Wednesday June 11, 2025
Desert Research Institute —
California’s Central Valley — one of the nation’s most critical agricultural regions and home to over 1.3 million people — is prone to flooding. Mapping the extent of winter floods has been challenging for experts, however, because clouds can obscure the view of satellites. Recent efforts to improve satellite flood mapping have been incorporated into a new study that offers insight into where winter flooding is occurring and inform how floodwaters can be used to replenish depleted aquifers.
The research, published June 4 in the Journal of Flood Risk Management, examined 20 years of satellite imagery to identify the extent and location of winter flooding in the region. The midwinter months of December through February were found to have the highest likelihood of floods, particularly when atmospheric rivers brought heavy rains when soils were already saturated. The study also identified areas where floodwaters fail to percolate through soils and offers suggestions for using the water to replenish rapidly depleting groundwater aquifers. By examining insurance claim data and overlays of floodwaters and buildings, researchers also found that flood exposure was actually higher, by value, for buildings outside of officially designated flood boundaries. The study’s findings can be visualized in three interactive maps.