Geography Reference
In-Depth Information
0.4375
0.375
0.3125
0.25
0.1875
0.125
0.0625
0
0.0625
0.125
0.1875
0.25
0.3125
0.375
0.4375
10 m
(b)
0.5 m
50 m
(a)
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
50 m
m
(c)
Figure 14.5 Laser scanned DEM (grey scale) of a 5881m 2 reach of braided gravel-bed channel draining the proglacial outwash fan of
Glacier du Mont Min´eandFerpecle situated in the Valais region of the Swiss Alps. (a) principal fine gravel bar features, (b) detail of
eroding bar margin showing collapsed sediment blocks, (c) difference surface showing erosion and deposition at sub-bar unit scale
(After Milan et al. 2007).
14.2.4 In-channel hydraulicunit scale
across scales similar to bar and sub-bar features. As
mentioned above, the Riegl LMS Z-201 laser scanner
is useful for investigating these hydraulic units as these
scanners operate using a near-infrared laser (0 . 9
Large and Heritage (2007) have employed terrestrial laser
scanning to characterise and map instream habitat in
the form of hydraulic biotopes. Biotopes are stage-
dependant, in-channel hydraulically-definedhabitat units
(e.g. Newson and Newson, 2000), and in UK rivers occur
m).
While much of the energy at this wavelength is absorbed
by still water, turbidity and surface roughness generate
low energy returns generally below 20% of the initial
μ
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