Optimal water allocation in the Zambezi basin

The Zambezi river basin is of utmost importance for the riparian countries in terms of energy, food production and natural resources. In 2030, the Zambezi river basin will support 80 million people and the population is expected to double within 30 years if current growth rates are maintained. This population growth will therefore lead to increasing water demands for food and energy, which may compete with ecological flows in environmentally sensitive areas. Even though there is no legal agreement on the sharing of Zambezi waters, we believe that an assessment of basin-wide economically efficient allocation policies will provide valuable information at a time where water managers and policy makers in the region are negotiating the establishment of a unified river basin institution called the Zambezi Watercourse Commission (ZAMCOM). That institutions would be responsible for, amongst other things, the design of allocation rules. In this study, basin-wide allocation policies are derived from an integrated, stochastic, hydro-economic model which considers the largest existing and planned hydraulic infrastructures and irrigation schemes in the basin. The model allocates water in space and time so as to maximize the net economic returns from both consumptive and non-consumptive uses over a given planning period. The analysis of simulation results reveal that most of the planned irrigation schemes in Zambia, Zimbabwe, Namibia, Angola and Botswana and not economically sound if the power stations that are in an advanced planning phase are implemented.