2. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP WELCOME TO THE SECOND AIACC WORKSHOP, DAKAR AF_42 RESEARCH TEAM BOTSWANA

3. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP Forecasting impact of climate change on runoff coefficients in Limpopo basin using Artificial Neural Network presenter: Prof. B.P. Parida University of Botswana, Gaborone

4. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP Area : 80 000 km 2 ~ 1/8 area of Botswana 4 Dams: 350 M Cum. Farm Land : ~ Food Security

5. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP

6. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP

7. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP The Limpopo Basin Multi-cell representation

8. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP YearRun off Coeff YearRun off Coeff YearRun off Coeff 1971 0.4019810.3519910.39 1972 0.2919820.3819920.35 1973 0.4719830.3519930.50 1974 0.4619840.3419940.43 1975 0.3719850.4819950.60 1976 0.5619860.4019960.55 1977 0.3519870.5219970.59 1978 0.2119880.3819980.43 1979 0.4819890.3619990.40 1980 0.3719900.5620000.45

9. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP 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

10. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP Source: Hydrological Sciences Journal

11. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP

12. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP 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)

13. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP 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.

14. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP

15. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP

16. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP Output of the best minimized performance function adopted for the study

17. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP Regression between target and modelled runoff coeffs T = TARGET A = ACHIEVEMENT

18. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP

19. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP Target and simulated runoff coefficients plotted for the entire study period

20. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP 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

21. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP Simulations up to year 2000 & Forecasts into the year 2016

22. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP A comparison between the forecasted runoff co-efficient obtained from ANN, EXCEL Tool Box & Extrapolation.

23. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP Comparison of Trend in Runoff Coefficints.

24. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP PeriodAvg. % increase ROCper year 1971 - 1980 : 0.409 1981 - 1990 : 0.41(2.5%)4.7 1991 - 2000 : 0.47(14.6%)6.1 2001 - 2010 : 0.48(2.13%)4.7 2001 - 2016 : 0.50(4.2%)3.8

25. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP 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.

26. Forecasting impact of climate change on runoff coefficient in Limpopo basin using ANN MARCH 24 -27, 2004AF_42 DAKAR WORKSHOP Thank You for listening