images by Henricus Peters
Trees are very important in our natural landscapes – never more so when it comes to the impacts of flooding….
Dr Gregory Moore, botanist, writes on The Conversation website :
“As the floodwaters recede, mountains of debris are left behind – sheets of plaster, loose clothes, mattresses and, of course, trees. Some debris I’ve seen in floods includes massive tree trunks weighing 5 tonnes of more, bobbing along like corks in the rapidly flowing waters.
The trees that line our creeks, rivers and floodplains are on the front line when major flooding occurs, and bear the brunt of the flood’s mighty forces. But while they are often victims of floods, trees are also our greatest allies.
From stabilising river banks with the strong grip of their roots to changing the course of floodwater, here’s how trees influence floods – and how floods can kill them.
How trees influence floods
The large and fine roots of trees, such as river red gums, bind and consolidate soil, stabilising river banks and reducing erosion. This reduces the amount of sediment entering waterways, and prevents waters down-stream becoming muddied and clogged with silt.
Large trees can also protect smaller plants such as shrubs by acting as a physical barrier, shielding other vegetation from the forceful momentum of floodwater. This is because the presence of trees slows the floodwaters’ speed, as their trunks, roots and branches block and deflect water, and change the direction of flow.
However, slowing floodwaters can also cause the flood front to widen, inundating areas further away from the usual river course. This is a major consideration when creek and river banks are being revegetated – we want to capture the benefits trees provide, but also ensure that if floodwaters slow down there’s no greater risk to property or life. “
Read the full article here
