Kgari, the largest sand island on earth, is famous for its crystal clear freshwater lake. New research from the University of Adelaide suggests these iconic bodies of water may be more vulnerable than previously thought.
Scientists have discovered signs of a major dry period during the mid-Holocene, about 7,500 years ago, by analyzing ancient sedimentary layers at Lake Kgari, located off the southeast coast of Queensland.
“Our study shows that some of Kgari’s deepest lakes dried up around 7,500 years ago, long after the end of the last ice age and during a period of high rainfall,” said lead researcher Associate Professor John Tibby from the University of Adelaide.
Associate Professor Tibby said dryness symptoms were not uncommon in Australia. However, this particular event stands out because it occurred during a period that was generally wetter than the current one.
“There are many lakes in Australia that have dried up because there wasn’t enough rainfall to sustain them during the Millennium Drought,” Associate Professor Tibby said. His research was published in Quaternary Science.
“Lake Kgari, which we studied, has existed for between 35,000 and 55,000 years, but the drying phenomenon we identified occurred unexpectedly during periods of heavy rainfall.”
Wind patterns and unexpected lake loss
Researchers believe changes in the wind system could help explain the mystery. Co-author Dr Harald Hofmann from the Commonwealth Scientific and Industrial Research Organization (CSIRO) said regional wind patterns are likely to influence where rainfall ends up.
“Previous studies have shown that heavy rains also occurred in Minjeriba during this period, but due to the southeast trade winds that were occurring at the time, rainfall from the south only entered the Minjeriba lake and not the Kgari lake,” he says.
Dr Hoffman said the discovery raises important questions about how Lake Kgari will respond to future climate change.
“This discovery highlights the urgent need to know more about Kgari’s beautiful lakes. The climate is predicted to become drier, but rainfall is becoming more intense, so we have no idea whether these lakes are at risk of drying up.”
Sediment records reveal water shortage
The researchers identified an ancient aridity phenomenon by detecting notable gaps in the sediments from some of the island’s oldest lakes.
“Lake sediments are like a diary, recording what happens in and around the lake,” says Professor Tibby.
Layers of pollen preserved in the mud can reveal what types of plants once grew nearby, while increased sand content may indicate increased erosion. If the sediment layer is completely missing, that indicates something more dramatic.
“Our study found that some of Kgari’s oldest lakes were depleted of sediment between 7,500 and 5,500 years ago. This indicates that the lake area was not covered by water, meaning there was no lake.”
Cultural significance of Kugari’s eyes
To the traditional owners, the Butula people, these lakes are known as the “Eye of Kgali”. Conway Burns, study co-author and Buturaman, emphasizes the importance of protecting them for future generations.
“Kugali is the name of the dreaming spirit who formed this island, and her eyes are more than just water, they are windows to eternity,” Burns says.
“When you stand in front of Lake Kgari, you don’t just see the reflection of the sky and the forest; you see the spirit of the country staring back at you. Her eyes hold ritual, memory, and the whispers of the Creator. They carry the voices of our departed ancestors and loved ones, guiding us with forgiveness, wisdom, and reflection.”
“These waters are sacred and secret. They are not ours to own, they are ours to protect. Because we are her children, we are entrusted with a heartfelt and eternal responsibility: to preserve her beauty, her spirit, her voice whispering through the streams and her eyes so that future generations can feel the same connection and respect.”
