Your guide to understanding levee banks and flooding
When you hear the word “levee” – do you think of a charge, tax, fee or fine? With many of us currently grappling with the high cost of living, it’s only natural that our minds should turn to levies of a financial kind!
But we’re talking about that other sort of levee, the kind famously mentioned in the 1970s hit song American Pie. If that’s the extent of your knowledge of levees, this blog is for you! Read on to learn all about levee banks, how they work and why they’re so important.
What is a levee?
A levee bank is an embankment or wall of earth along a river to hold the water in the river channel during a flood. The purpose of a levee bank is to protect the area behind the levee bank from flooding.
Levee banks reduce the likelihood of flooding and the risks of flooding to life, assets and the environment.
Levee banks can be permanently in place nearby a river or temporary as required in a flood event.
How do levee banks work?
Much more than just piles of dirt, levee banks play a very important role in protecting people, property, crops and infrastructure from floods.
An effective levee bank is constructed in the right position near a river, allowing space for flood waters but stopping them from flooding people’s houses, sheds, properties, crops or other infrastructure and buildings.
They are designed to a height and constructed with the right materials so that when the river is flooding, the water stays in the river channel, up to a certain flood level.
Levee banks reduce the risk of flood, but do not eliminate that risk completely.
What happens if a levee bank breaks? And how does that happen?
Sometimes levee banks break during floods even when the flood level is lower than the levee bank. This can happen if the levee bank was not constructed properly or has not been maintained. Causes of levee bank faults can include:
- Burrowing animals
- Rotting tree roots
- Settling or cracking
- Seepage (foundation material is allowing water through the levee bank)
- Slumping (a part of the levee bank has collapsed)
Even a well-designed and maintained levee can be overtopped if a flood is greater than what the levee bank was designed to protect from.
Does South Australia have levee banks?
Yes! You can find levee banks in many parts of South Australia, including:
- extensive levee banks on the River Murray at Renmark and the lower River Murray, and smaller sections at Paringa, Lyrup and Berri
- levee banks on the Gawler River, Little Para River, Dry Creek, Onkaparinga River, River Torrens and Hindmarsh River.
Management of levee banks
The South Australian government is committed to improving levee bank management. This includes documenting existing levee banks, identify priority areas, determining formal management arrangements and seeking funding for works needed.
Read more about the Department for Environment and Water’s Levee bank management project.
During the 2022-2023 River Murray flood event, 20 levee banks in the Lower Murray Reclaimed Irrigation Area (LMRIA) were overtopped or breached, causing damage to the levee network and inundating large areas of agricultural land. There is a current project underway to repair these levee banks to their pre-flood height.
Read more about the Department for Environment and Water’s LMRIA Levees Intermediate Remediation project.
Flooded with information yet? If you want to learn more about levee banks and flooding, check out:
- The Department for Environment and Water’s Learn about flooding webpage.
- The South Australian Flood Awareness Map where you can look up your address and check your flood risk.
- The South Australian levee bank dataset including high resolution LiDAR and aerial photography.
