Grasslands and cattle ranches sprawl across the hot Barkly Tableland area of Australia’s Northern Territory. But when its rainy seasons are especially rainy, a network of ephemeral lakes can become inundated, with water covering thousands of square kilometers.
Two rather wet years in a row allowed Tarrabool Lake and Lake Sylvester, seen in the images above, to expand appreciably. The rainy seasons in 2022–2023 and 2023–2024, which stretch from October through April, were both among the top ten wettest in northern Australia since 1900. The Australian Bureau of Meteorology reported that rainfall was “very much above average” in this region of the Northern Territory in both seasons.
This series of images, acquired by the MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA’s Aqua and Terra satellites, shows the evolution of Tarrabool Lake and Lake Sylvester between November 2022 and November 2024. Near the start of the wet season in 2022 (left), only Lake Sylvester appears to contain any water. Rains later in the season, including several days of downpours in early March 2023, helped fill in the lakes enough that water persisted into the start of the next rainy season.
In November 2023 (center), Tarrabool Lake is visible where the land was previously dry, and Lake Sylvester has expanded and merged with adjacent ephemeral lakes. The ensuing 2023–2024 wet season included the tenth-wettest January and second-wettest March on record for northern Australia. Contributing to that, severe tropical cyclone Megan brought widespread rainfall to the region in March. The Northern Territory’s Barkly Highway flooded enough in places following that event for fish to be seen crossing the road.
Early in the 2024–2025 wet season, the lakes covered more area than at similar times in the past two years. The OLI (Operational Land Imager) on the Landsat 8 satellite captured this image showing their extent on October 30, 2024. Lake Sylvester had merged with nearby Corella Lake and Lake Deburgh. Likewise, the water in Tarrabool Lake had connected with an area known as Eva Downs Swamp to the northwest to form a single freshwater wetland. Both systems are considered important areas for waterbirds. Together, when fully flooded, the wetlands span approximately 4,750 square kilometers (1,830 square miles), nearly the size of the state of Delaware.
According to a report from the Australian Bureau of Meteorology and the Commonwealth Scientific and Industrial Research Organisation (CSIRO), the amount of annual rainfall in the Barkly region has trended upward in recent decades, and evaporation rates have declined. Still, rainfall is highly variable from year to year. It falls more reliably from December to March, when monsoonal weather patterns tend to form.
NASA Earth Observatory images by Lauren Dauphin, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview, and Landsat data from the U.S. Geological Survey. Story by Lindsey Doermann.
