Water resources estimation in less developed regions – issues of uncertainty associated with a lack of data

There is an urgent need within less developed regions for tools to quantify water resources and their variability and to determine the impacts of development scenarios. While there has been a relatively long history of the practical application of hydrological and water resource models in southern Africa, the quality of the results are constrained by the limitations of the available data. There are unanswered questions about what the scientific and practical priorities should be in terms of improving predictions and reducing uncertainty. The paper provides some background to the problem through a brief review of the use of models in the region, the quality of the available data and some of the constraints. The overall conclusion is that there is a need to improve the access to, and the reliability of, model input data. Unless these issues are resolved, improvements in modeling approaches are unlikely to result in reducing uncertainties in simulation results.