Floods - Extreme Events: A Physical Reconstruction and Risk Assessment - page 71

Figure 3.9. Bedrock scour concavity in limestone, in a tributary (Broken River) of
the Burdekin River, North Queensland. The scour concavity marks the height of past
floods. Note the dog in the right foreground for scale.
remains to be thoroughly investigated. However, Dury (1973)argued that bedrock
meander wavelengths are a function of more frequent flood events. Dury noted
though that many bedrock streams have meander wavelengths that appear too
large to have formed under modern high frequency flood discharge events. He
suggested that this phenomenon is best explained by climatic change where the
present climate is less humid and the size of floods has decreased to the present
day. In other words, the large meander wavelength of the bedrock channels is
due to a wetter climate in the past when the size of the 2--3 year flood was much
greater. The modern streams, which display meander wavelengths smaller than
that of the bedrock gorge in which they flow, were termed 'underfit streams' by
Dury.
While the relationship between meander wavelength and climate change in
bedrock channels is ambivalent, there is little doubt that high frequency floods