Geology Reference
In-Depth Information
Fig. 6.3
Spatial variability of both unconcentrated and concentrated erosion combined along a uniform, planar,
100-m long × 30-m wide slope according to differing rainfall intensity as predicted by MAHLERAN (after Wainwright
et al
., 2008b).
to a series of plots of different lengths in the same
environment, with similar slopes and vegetation
covers (Wainwright
et al
., 2008c). These plots had
been monitored for a period of three years for run-
off and erosion responses to natural rainfall
events. While the results of this test showed a
poorer goodness-of-fit, they produced results that
predicted the correct ordering of events, even if
the absolute magnitudes were not always well
simulated (Fig. 6.4). Further assessment of these
tests suggested that there are also a number of
limitations of subcomponents of submodels, not
least because research has tended not to concen-
trate on parameterizing transport distances and
virtual velocities for different particle sizes in dif-
ferent transporting mechanisms, in part because
typical erosion models make no use of these data,
but also because of the technical difficulties in
obtaining them. In this case, modelling across dif-
ferent scales has demonstrated the weaknesses of
existing empirical and conceptual support for
understanding erosion processes, and the link
between data collection and theoretical under-
pinning, as discussed in the introduction.
6.6 Erosion and Landscape Evolution
As discussed above, Zhang
et al
. (2002) demon-
strated that scaling from event to monthly and
annual timescales in process-based models is
not straightforward because of non-linearities in
