Geoscience Reference
In-Depth Information
TABLE 8.3
Software Settings Used in GEP Estimation of Pan Evaporation
Variable
Setting
Number of chromosomes
30
Head size
8
Number of genes
3
Linking function
Addition
Fitness function
Relative root squared error
Generation
10,000 (user defined based on previous experience of when a
good generalisation is achieved)
Mathematical
Default functions: addition, subtraction, multiplication, division,
square root, exponential, natural logarithm,
x
to the power of 2,
x
to the power of 3, cube root, sine, cosine, arctangent
With parsimony pressure
No
Enable complexity increase
No
Mutation
0.044
Inversion
0.1
IS transposition
0.1
RIS transposition
0.1
One-point recombination
0.3
Two-point recombination
0.3
Gene recombination
0.1
Gene transposition
0.1
Numerical constants
Constants per gene
2
Lower bound
−10
Upper bound
10
Data type
Floating point
RNC mutation
0.01
Dc mutation
0.044
Dc inversion
0.1
Dc IS transposition
0.1
Figure 8.6 presents the results of an analysis of the solutions of how each Sub-ET functions in
relation to the overall
E
PA N
solution. For this particular model, it can be seen that each Sub-ET
has a valuable role to play, suggesting sub-model redundancy is minimal. The diagram supports
the claim made by Ferreira (2001) that GEP utilises sub-solutions, which specifically offer their
own individual returns, in addition to that supplied by the collective sum of numerous internal
components. Useful future research might focus on determining whether each sub-ET is solving
a particular facet of a problem and how these sub-models relate to the physical processes that
control
E
PA N
.
8.4.2 r
ainfall
-r
unoff
M
odelling
Flood forecasting is an important aspect of applied hydrological sciences because of how it con-
tributes to the assessment and estimation of the hazards associated with rainfall, lake levels, river
levels and potential drought or flooding. This case study shows how GP can be used rainfall-runoff
modelling for the Annapolis River in Nova Scotia, Canada, using standard meteorological and
hydrological records. The location of the catchment is shown in Figure 8.7.
