NISAR Reveals Major Flooding In Mozambique

An Earth-observing satellite mission launched in 2025 by NASA and the Indian Space Research Organisation (ISRO), NISAR uses synthetic aperture radar (SAR) to image of nearly all of Earth’s land and ice surfaces. A SAR system works by transmitting microwaves, which interact with the surface and reflect back to the sensor. Scientists use the information in the return signals to create detailed images of the surface, and by comparing images of the same area at different times, they can observe change that has occurred. An advantage of radar is that it allows NISAR to see through clouds, in darkness or in light.

Early in 2026, NISAR’s L-band SAR observed a flood that struck southern Mozambique around the Limpopo and Incomati river basins. This flooding was triggered by intense seasonal rainfall in December and January, which displaced over 600,000 people, damaged 400,000 acres of cropland, and flooded 30,000 homes. NISAR captured images on Jan. 5 and Jan. 17, 2026, that show the extent of the flooding throughout the river basins.

NISAR transmits and receives radio waves of different polarization. In a typical observation scenario, two bands of imagery are acquired, referred to as HH (horizontal polarization on transmit and receive) and HV (horizontal polarization on transmit and vertical on receive). These different polarizations can tell us about how the radio waves scatter off Earth’s surface. In these visualizations, the HH band is assigned to red, the HV band to green, and the ratio of these two bands to blue.

The different colors on the map indicate the likely characteristics of the surface. For example, magenta areas, because they are showing strongly in the red (HH) channel, suggest that the waves are reflecting off flooded forests. Green parts of the map indicate areas where the polarization of the waves has changed from horizontal to vertical, perhaps scattered in many directions by tree canopies — a phenomenon called volume scattering. Dark blue areas signify open water.