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When good rivers turn bad: Extreme flooding
Case study - The Johnstone River, Far North Queensland

Carello's Levee

Impact of Modified Carello's Levee - Click to enlargeModifying the shape of Carello's Levee

This levee protects a residential suburb but also reduces the flow of the main river channel.

Impact of Scheme 1 Dredging - Click to enlargeDredging the river channel

By removing accumulated river silt from the main channel, river flow is increased. But dredging lasts only a short time and is expensive. Flooding rivers carry huge volumes of sediment. Sediment load can only be reduced by revegitating river banks upstream.

Impact of Carello's Channel on 2 Year ARI - Click to enlargeImpact of Carello's Levee on once in two year flood

The levee protects those on the left bank but puts those on the right bank at greater risk.

Impact of Carello's Channel on Peak 10 Year ARI Flood Levels - Click to enlarge Impact of Carello's levee on once in ten year flood

In a once in ten year flood a considerable area od the right bank is inundated to protect a small but populated area on the left bank.

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1. Origins of extreme weather | 2. Finding hidden treasure | 3. Streams and mass wasting
4. The Johnstone River, FNQ


The resources contained in this unit are courtesy of Earth Science Australia http://earthsci.org/