Geology Reference
In-Depth Information
Table 14.2
Comparison of SHETRAN with five physically-based erosion and sediment yield models.
Model feature
SHETRAN
ANSWERS
WEPP
EUROSEM
LISEM
InHM
Simulation type:
Continuous
Y
N
Y
N
N
Y
Single event
Y
Y
Y
Y
Y
Y
Maximum basin size
2000 km
2
Order 100 km
2
2.6 km
2
Small basin
Small basin
Order 100 km
2
Spatial distribution
Grid
Grid or GIS raster
Grid
Uniform slope
planes
GIS raster
Finite element
mesh
Overland flow:
Rainfall excess
Y
Y
Y
Y
Y
Y
Upward saturation
Y
N
N
N
Y
Y
Erosion process:
Raindrop
impact/ overland
flow
Y
Y
Y
Y
Y
Y
Rilling
N
N
Y
Y
Y
N
Crusting
N
Y
N
Y
Y
N
Channel banks
Y
N
N
Y
N
N
Gullying
N
N
N
N
N
N
Landsliding
Y
N
N
N
N
N
Roads
N
N
N
N
N
Y
Output:
Time-varying
sedigraph
Y
Y
N
Y
Y
Y
Time-integrated
yield
Y
Y
Y
Y
Y
Y
Erosion map
Y
Y
Y
N
Y
Y
Land use
Most vegetation
covers
Mainly agricultural
Wide range
Mainly agricultural
Mainly
agricultural
Most vegetation
covers
of land uses
Y, yes; N, no.
and forests, which can be simulated by SHETRAN,
WEPP and potentially InHM.
As noted by Merritt
et al
. (2003), most models
tend to represent only one of the broad erosional
processes. All those in Table 14.2 consider soil
erosion by raindrop impact and overland flow in
some form. WEPP, EUROSEM and LISEM repre-
sent the process in considerable detail, account-
ing for rilling, crusting and other effects. However,
these effects are most significant at small scales
and may merge with or become dominated by a
wider range of erosion controls at larger scales (de
Vente & Poesen, 2005). Other specialist classes of
models consider erosion by gullying (e.g. Bull &
Kirkby, 1997; Sidorchuk, 1999; see Chapter 19)
and by landsliding (e.g. Montgomery & Dietrich,
1994; Wu & Sidle, 1995; Dietrich
et al
., 2001;
Dhakal & Sidle, 2003; Sidle & Ochiai, 2006).
However, of the physically-based, basin-scale
models, only SHETRAN currently provides a
framework within which components have been
developed for raindrop impact/overland flow ero-
sion, landslide erosion, channel bank erosion
(albeit at a simple level) and transport of contami-
nants adsorbed to sediment particles, and within
which a preliminary design has been developed
for a gully erosion component (Bathurst
et al
.,
1998a). A class of semi-quantitative models that
