9 Conclusion and Recommendations

9.1 Conclusion

This research made a start in investigating the impacts of climate change on the reliability of power generation output of the Kariba dam. This is done by calibrating and validating the HBV model to observed historical data. A drought analyser function is set up which functions by detecting water years in which a minimum cumulative inflow sum is not met. The droughts are then classified into severity based on the measured deficit.

For the historic time period and the five climate scenarios the discharge at Katima Mulilo is simulated and the drought analyser function is applied to the data. The results are then analysed through probability distribution functions, cumulative distribution functions, and plotted return periods. Based on the simulated discharge generated by this calibrated model, for each of these climate scenarios, drought events appear to occur more often and are more extreme in nature. However, further research must be done to quantify the frequency of drought events, as the data input is not extensive enough to draw definitive conclusions for the climate scenarios.

The main research question of this paper stated, To what extent will varying climate scenarios influence the frequency and severity of droughts of the Zambezi river and what are the implications for the reliability of the Kariba Dam as a source of energy?’. A direct answer to this question cannot be given based solely on the results of this research. To do that a much more extensive research needs to be completed, with longer data periods, more hydrological models and more ensembles per model. The uncertainty of all these models then also needs to be taken into account.

However, the research is indicative of a few key takeaways. Firstly, it is indeed likely that in any future climate scenarios, stipulated by the IPCC, the occurrence of drought events will increase and they will likely more commonly be of an extreme nature. Nevertheless, the recent ‘failing’ of the Kariba dam, cannot be attributed entirely to climate change. The dam has been standing for over 60 years, and in its lifespan the conditions for which it was designed have changed drastically. The percentage of the population that has access to electricity has increased, and the demand per capita has increased with it. Moreover, the population is expected to grow substantially coming decade. As a hydropower source the Kariba dam has limitations to how much more supply it can deliver with the same water inflow. Zambia and Zimbabwe will indeed have to look to other sources of power to meet the immensely growing power demand of both countries regardless of the impacts of climate change on the system.

9.2 Recommendations

For reasons stipulated in Chapter 3 the HBV model was chosen to simulate the observed data. For future research, it is recommended to also repeat the research for more hydrological models, and many more ensembles, and compare their ability in simulating the observed data.

Furthermore, it is recommended for future research to improve upon the developed drought analyser. As elaborated in Section 8.1, dynamically modelling the water-level height would allow for much more definitive conclusions to be drawn regarding detecting years in which the Kariba dam cannot meet a certain power output, even with the available reserves.

Finally, a further study could elaborate on the extension research mentioned in Chapter 7. Population growth, and changes in percentage of the population connected to the national power grid play a substantial role in why the Kariba dam has failed to provide sufficient output in recent years. Climate change is not the sole contributor to this problem. To complete this research, a study could be done regarding the high hydro based power dependency of the region and future possibilities for power diversification.