After two particularly wet years, large ephemeral lakes in the Barkly Tableland region of Northern Australia were still flooded as the 2024–2025 rainy season got underway.
Consecutive seasons of heavy rainfall have transformed the ephemeral lakes of Australia’s Barkly Tableland, with Tarrabool and Sylvester Lakes expanding significantly, evidenced by satellite data from NASA’s MODIS. The area has become an essential habitat for waterbirds.
Rainfall and Lake Expansion in Australia’s Northern Territory
The Barkly Tableland in Australia’s Northern Territory is a vast region of grasslands and cattle ranches. During particularly heavy rainy seasons, this arid landscape transforms as ephemeral lakes swell, sometimes covering thousands of square kilometers.
Back-to-back wet years in 2022–2023 and 2023–2024 fueled significant expansions of Tarrabool Lake and Lake Sylvester. These rainy seasons, which run from October to April, ranked among the top ten wettest in northern Australia since 1900. According to the Australian Bureau of Meteorology, rainfall in this part of the Northern Territory was classified as “very much above average” in both years.
Satellite Observations of Ephemeral Lakes
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.
Record-Breaking Rainfall Events
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 acquired 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.
Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.