Geology Reference
In-Depth Information
The quantity of input data available to predict the desired output and subse-
quently a reliable model was analyzed using the M-test. The variation of the
Gamma values and Standard Error (SE) corresponding to the data points for the
above-mentioned three inputs are shown in Fig.
7.20
. The variation of the Gamma
values and the SE corresponding to the data points for all the inputs is shown in
Fig.
7.21
, where we can note that, even though the Gamma value is a little higher
for [W, T, Ed] than [W, RH, Ed] input sets, modeling with all available weather
variables can make a model with less complexity (less gradient and the SE).
However, it is dif
cult to make a decision right now on which model we should
choose for modeling. The combination [W, RH, Ed] is better if we consider the
minimum Gamma value, whereas the combination [W, T, Ed] has less complexity
and SE compared to the earlier model. Even though the Gamma value (0.0217) of
[W, T, Ed] is a little higher than that of [W, RH, Ed] (0.0216), both numerical
values are very close. The M-test analysis results of [W, T, Ed] input combinations
are shown in Fig.
7.22
.
From Table
7.5
we can deduce that the combination of daily wind speed, daily
relative humidity, and daily saturation vapor pressure de
cit can make a good
model, comparable to the combination which composes all inputs. The relative
importance of inputs is W > Ed > RH > T in terms of Gamma statistic values. It
does not mean that daily mean temperature has no effect on evaporation. The
significance of the daily mean temperature data set was relatively small when
compared to other input sets, since the elimination of this input made less variation
in the Gamma statistic value. It may be because the saturation vapor pressure is a
function of temperature and that data itself indirectly re
ects the temperature data
information. The M-test analysis results in different scenarios are shown in
Fig.
7.23
, including
“
All,
”“
No W,
”“
No T,
”“
No RH,
”
and
“
No Ed
”
(the scenario
“
All
”
corresponding to all four inputs, and other scenarios corresponding to
