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Wet Season Transforms the Zambezi River
This page contains archived content and is no longer being updated. At the time of publication, it represented the best available science. However, more recent observations and studies may have rendered some content obsolete.
The Zambezi River forms part of the border between Zambia and Namibia, where the Caprivi Strip juts eastward from the rest of Namibia. Flowing down a gentle gradient in this region, the Zambezi often spills onto floodplains during the rainy season, with water levels peaking between February and April.
Water levels were high when the Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite observed this stretch of the river on March 31, 2013 (top image). For comparison, the bottom image shows the river on August 25, 2012, during the dry season. Both the river and the surrounding floodplain show sharp differences.
The Zambezi River flows through braided channels, and the main channel appears swollen in March 2013; its bluer color indicates greater water depth. But the differences in the floodplain dwarf changes in the channels. Where browns and tans of dried vegetation and burn scars prevail in the dry season, green plant life is revived in the wet season. The water-loving floodplain grasses surrounding the Zambezi River depend on annual floods and seasonal rainfall that is relatively abundant compared to much drier areas to the west.
The spread of water and vegetation in the wet season appears more or less confined within an uneven boundary north of the river, suggesting a rise in elevation along that floodplain margin. The vegetation provides food for a multitude of fish and animal species.
Although the Zambezi River watered its floodplains generously in late March 2013, conditions were in fact fairly dry for the season. In early April 2013, the U.S. Agency for International Development (USAID) reported that a large stretch of southern Africa, including the Caprivi Strip, was in the midst of drought. The bulletin stated: “Many local areas in Angola and Namibia have experienced less than half of their normal rainfall accumulation since January, as pronounced dry spells have affected parts of Zambia, Botswana and South Africa since February. The likelihood for recovery is minimal as the southern African monsoon season is coming to an end.”
NASA Earth Observatory image created by Jesse Allen and Robert Simmon, using Advanced Land Imager data from the NASA EO-1 team. Caption by Michon Scott and Robert Simmon.
Along the Zambia-Namibia border, the Zambezi River showed sharp contrasts between August 2012 and March 2013.