After two particularly wet years, large temporary lakes in northern Australia’s Barkley Tableland were still flooded as the 2024-25 rainy season began. Successive seasons of intense rainfall have transformed ephemeral lakes on Australia’s Barkley Plateau, as NASA’s MODIS satellite data show; Tarrabul and Sylvester lakes have expanded significantly. This area has become the main habitat for wetland birds.

Rainfall and lake expansion in Australia’s Northern Territory

The Barkley Plateau in Australia’s Northern Territory is a large region of pastures and cattle farms. Particularly during heavy rainy seasons, this arid landscape sometimes changes with the formation of temporary lakes covering thousands of square kilometers.

Consecutive wet years between 2022–2023 and 2023–2024 contributed to the significant expansion of Tarrabul and Sylvester lakes. This wet season, which runs from October to April, has been among the ten wettest seasons in Northern Australia since 1900. According to the Australian Bureau of Meteorology, rainfall in this part of the Northern Territory was classified as “well above average” in both years.

Satellite observations of ephemeral lakes

This series of images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua and Terra satellites shows the evolution of Lake Tarrabul and Lake Sylvester between November 2022 and November 2024. At the start of the rainy season in 2022 (left), only Lake Sylvester appears to have water. Subsequent rains, including several days of heavy rains in early March 2023, helped fill the lakes sufficiently to hold water until the start of the next rainy season.

Lake Tarrabul is visible in November 2023 (center); here the land was previously dry, and Lake Sylvester expanded and joined nearby temporary lakes. The next wet 2023–24 season included the tenth wettest January and second wettest March on record in northern Australia. This was facilitated by powerful tropical cyclone Megan, which brought heavy rainfall to the region in March. Following the incident, the Barkley Highway in the Northern Territory was flooded in places, so fish were seen crossing the road.

Record rainfall amount

At the beginning of the 2024-2025 rainy season. The lakes covered a larger area than in the same period of the last two years. The OLI (Operational Land Imager) on the Landsat 8 satellite acquired this image showing their extent on October 30, 2024. Lake Sylvester is joined by nearby Lake Corella and Lake Deburg. Similarly, the waters of Lake Tarrabul merged with the area to the northwest known as the Ewa Highlands Marsh to form a single freshwater wetland. Both systems are thought to be important for waterfowl. When fully submerged, wetlands cover an area of ​​approximately 4,750 square kilometers (1,830 square miles), nearly the size of the state of Delaware.

According to a report by the Australian Bureau of Meteorology and the Commonwealth Scientific and Industrial Research Organization (CSIRO), annual rainfall in the Barkley region has tended to increase in recent years while evaporation rates have decreased. However, the amount of precipitation varies greatly from year to year. It falls more reliably from December to March, when monsoon weather conditions generally occur.