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Forecasting impact of climate change on
WELCOME TO THE SECOND AIACC
runoff coefficient in Limpopo basin using ANN
WORKSHOP, DAKAR
AF_42 RESEARCH TEAM
BOTSWANA
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecastingimpact
impact of
change
on on
Forecasting
ofclimate
climate
change
runoff
coefficient
in Limpopo
basin using
ANN
runoff
coefficients
in Limpopo
basin
using Artificial Neural Network
presenter:
Prof. B.P. Parida
UniversityAF_42
of Botswana,
MARCH 24 -27, 2004
DAKAR WORKSHOPGaborone
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Area :
80 000 km2
~ 1/8 area of
Botswana
4 Dams:
350 M Cum.
Farm Land :
~ Food
Security
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Multi-cell representation
The Limpopo Basin
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Year
Run off Coeff
1971
0.40
1972
0.29
1973
0.47
1974
0.46
1975
0.37
1976
0.56
1977
0.35
1978
0.21
1979
0.48
MARCH 24 -27, 2004
1980
0.37
Year
Run off Coeff
1981 0.35
1982 0.38
1983 0.35
1984 0.34
1985 0.48
1986 0.40
1987 0.52
1988 0.38
1989 0.36
AF_42 DAKAR WORKSHOP
1990
0.56
Year
Run off Coeff
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
0.39
0.35
0.50
0.43
0.60
0.55
0.59
0.43
0.40
0.45
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Why runoff coefficient (roc) ?
Rainfall ~ Runoff complex
roc = (total runoff) / (total rainfall)
Assumed to marginalize the impact of
land use changes
decrease in rainfall ~ increase in roc
decrease in roc
~ decrease in flow
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Source: Hydrological Sciences Journal
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Dendrides
Cell body
Axon
Nucleus
Axons
Nucleus
Dendrites
MARCH 24 -27, 2004
Sunapses
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Biological Neuron - specific type of cell - provides
cognitive and other related activities.
- Neuron collects signals from dendrites
- Spikes of electrical activity sent out by a neuron
through – long thin strands – axon which is split into
thousands of branches
- At the end of each branch – synapse, which converts
the activity from axon into electrical effects that
excite activity. ( changing effectiveness of synapse,
influence from preceding neuron is influenced)
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Artificial Neuron – simulates the four basic
components as well as functioning of the natural
neuron.
- Each neuron receives output from many other
neurons through input path.
- Each of the inputs to a neuron is multiplied by a
weight.
- Products are then summed up and fed through a
transfer function to generate an output.
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Xo
Wo
W1
X1
Sum
W2
Transf er
X2
Output
path
W3
X3
.
.
.
Processing
element
W4
Xn
Inputs Xn
Weights W n
The basic structural functioni ng of a neuron
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
First and hidden layer
Input neurons
Output layer
neuron
Input array
Output array
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Output of the best minimized performance function
adopted for the study
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
T = TARGET
A = ACHIEVEMENT
Regression between target and modelled runoff coeffs
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Conf. Levl
MSE
PCs used
2.5
Quantity value
2
1.5
1
0.5
0
1
2
3
4
5
6
Quantity optimized
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
7
8
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Target and simulated runoff coefficients plotted for
the entire study period
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Input variables used:
Annual Rainfall and Annual Evaporation
Target /Output variable:
Water balance computed runoff coefficients.
Training Algorithms Used: Automated regularization with early stopping
(as it outclassed others)
Transfer functions used:
Log-sigmoid for hidden layer
and purelin for the output layer.
The optimum number of neurons in the hidden layer: Fifteen
Final Choice of Architecture: Was arrived using PCA,
was also found to be the best with two
components used and at 0.001 significance level.
For Forecasting/Prediction: Model Predictive Control
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Simulations up to year 2000 & Forecasts into the year 2016
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Runoff Coefficients
0.70
0.60
0.50
By Extrpolation
0.40
Excel Toolbox
0.30
By ANN
0.20
….
0.10
20
15
20
13
20
11
20
09
20
07
20
05
20
03
20
01
0.00
Year
A comparison between the forecasted runoff co-efficient
obtained from ANN, EXCEL Tool Box & Extrapolation.
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
y = 0.0035x + 0.4908
0.70
y = 0.0004x + 0.4833
y = -0.0006x + 0.4468
0.60
0.50
By Extrapolation
0.40
Using ANN
0.30
Using Excel Tool Box
0.20
0.10
0.00
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
Comparison of Trend in Runoff Coefficints.
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Period
1971 - 1980 :
1981 - 1990 :
1991 - 2000 :
2001 - 2010 :
2001 - 2016 :
MARCH 24 -27, 2004
Avg.
ROC
0.40
0.41 (2.5%)
0.47 (14.6%)
0.48 (2.13%)
0.50 (4.2%)
AF_42 DAKAR WORKSHOP
% increase
per year
9
4.7
6.1
4.7
3.8
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
In conclusion:
It is evident that the by the next two
decades runoff is likely to decrease
so a good water management strategy
will be necessary as a possible
adaptation measure.
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP
Forecasting impact of climate change on
runoff coefficient in Limpopo basin using ANN
Thank You for
listening
MARCH 24 -27, 2004
AF_42 DAKAR WORKSHOP