SCHRIFTENREIHE Institut für Pflanzenernährung und Bodenkunde ...

Chapter 5 Modeling Grazing Effects on Coupled Water and Heat Fluxes in Inner Mongolia Grassland
Accumulative
interception (mm)
Accumulative
rainfall (mm)
20
16
12
8
4
0
240
200
160
120
80
40
0
UG 79 UG 99 WG HG
20-May 9-Jun 29-Jun 19-Jul 8-Aug 28-Aug 17-Sep
20-May 9-Jun 29-Jun 19-Jul 8-Aug 28-Aug 17-Sep
Time (days)
Fig. 5.4. Cumulative canopy and residue interception calculated by SHAW model for the
four sites during the growing period in 2006 (accumulative rainfall as a reference).
Model parameterization was conducted from 1 Aug. to 31 Aug. 2004. The
general trend in terms of model approaches is the same in different sites, this is
exemplarily demonstrated for the treatment UG 79 at 5, 20, and 40 cm depths
(Fig. 5). Except for the inverse model, all model approaches underestimate soil
moisture at 40 cm depth, which might be associated with a high unsaturated
hydraulic conductivity in this layer. Model accuracy among the five model
approaches is compared in terms of RMSE (Table 4). The RMSE is the lowest
for inverse model exhibiting the best goodness-of-fit, followed by LDP and then
NN. This proofs that the calibrated and measured parameters are more accurate
than the statistical estimations based on pedotransfer functions (PTFs). The
weakest predictions are found for LDP-NN and LDP+NN, i.e., the approaches
which measured and statistical parameters were mixed. However, the prediction
by LDP-NN is closer to that by LDP, indicating that parameters θr, θs, α, and n
are more sensitive than Ks, which is also supported by the fact that the
estimation by LDP+NN is almost identical to that by NN.
99