Unification Church of the United States

• Fish, turtles, crayfish and other aquatic animals retreat to these vital refuges.
• But our research, published today, reveals these waterholes are in danger of filling up with eroded soil from farms.
• This is putting a big squeeze on life in the river.
• When drought breaks, the water flooding into the river carries soil along with it.

Poking at sediment to understand waterholes

• Waterholes in the Moonie River can be more than 5 kilometres long, up to 5 metres deep, and teeming with life.
• We studied three of the deepest waterholes in the Moonie River, as they are the ones that last longest in droughts.
• Using metal rods, we probed the soil’s depth at evenly spaced points along the waterholes.
• Our sediment dating revealed that, in places, more than two metres of soil had filled the deepest waterholes since the 1950s.

Do floods remove soil from waterholes?

• In 2010 and 2011, the Moonie River experienced two very large floods.
• To unravel this, we examined how the sediment had changed since before the floods.
• We observed distinct layers, like those in a B52 cocktail, indicating the sediments had been deposited over a series of flows and floods since the 1950s, rather than solely after individual floods.

How can we solve this problem?

• In the Moonie River, water extraction for human use is minimal, so the problem is unlikely to lie with the river’s flow regime.
• Then determine the most effective ways to prevent erosion and reduce the amount of soil entering the river.
• These actions are essential for safeguarding the diverse aquatic animal life and the people that depend on waterholes for survival during droughts.
• John Tibby receives funding from the Australian Research Council, The Australian Nuclear Science and Technology Organisation, the Queensland and South Australian Governments.