What role do floods play in the environment?

As Victorian residents try and make sense of another serious flood event, we take a look at some of the positive ecological outcomes of flooding.

Tuesday, June 15, 2021

Picture: Latrobe River just to the south of Tanjil South, looking upstream.

As the cleanup continues for Victorians living in the states North and hard-hit Gippsland region, there are many of us still coming to terms with another serious flood event. Many thousands of Victorian residents have gone without power for multiple days, and many more will begin the daunting task of significant damage repairs and insurance claims.

While flood impacts are a serious concern for lives and livelihoods, some are also positive. Flooding is a natural ecological process that plays an integral role in ensuring biological productivity and diversity in floodplains wetlands, billabongs, rivers, and streams.

Floods link the river with the land surrounding it, recharge groundwater systems, fill wetlands, increase the connectivity between aquatic habitats, and move both sediment and nutrients around the landscape, and into the marine environment.

Picture: Tanjil River, looking upstream from Moe-Walhalla Road

Within these natural ecosystems, many plants and animals rely on flooding for their species to prosper.

From an article in Australian Geographic after the disastrous 2011 Queensland floods, Professor Richard Norris, an ecologist at the University of Canberra, was positive about the rejuvenating aspects of floods.

“A lot of floodplain vegetation is dependent on rejuvenation after floods, particularly those species that depend on [them] for seeding and germination."

Other plant species, like the famous River Red Gum, need the occasional drink that floods provide when they’re away from the permanent water’s edge.

Some bird species breed opportunistically as a response to flooding, even travelling thousands of kilometres to do so. Colonial nesting waterbirds, in particular, require substantial floods to support large breeding events in floodplain wetlands. These include egrets, ibises, pelicans, cormorants and herons.

Professor Richard Kingsford, director of the Australian Wetlands and Rivers Centre at the University of New South Wales, says floods are hugely important to the Australian environment. Indeed, an endangered waterbird, the Australian bittern, “depends on floods to create breeding habitats, particularly in the Murray Darling Basin.”

Picture: Tanjil River at River Connection Road, Willow Grove

Plant and bird species aren't the only ones that rely on floods. Some fish species commence spawning as a result of a flood event, while flooding can also help fish move up or down a waterway.

While our thoughts are always with people affected by floods, it's also a timely reminder that floods play an important role in our natural environment.

Did you know?

You might also like to know that our teams play a role in managing floods. Our Landscaping teams specialise in constructed urban wetlands and waterways, which are often required to hold water runoff in urban areas, especially during flood events. We also conduct planting and revegetation projects for Water Authorities and Catchment Management Authorities, helping them manage water assets designed to mitigate the effects of flood events.

Pictured below: a before and after photo of our Tyers constructed urban wetland. The first photo shows the wetland planting almost finished, just a week before the floods. The second photo shows the wetland holding significant flood water.