- Annex 9: Hughes D., Mantel S. and Farinosi F. , 2020. Assessing development and climate variability impacts on water resources in the Zambezi River basin: Initial model calibration, uncertainty issues and performance. ACEWATER2 report JRC120956 (Main deliverable)
Study region: The Zambezi River basin, one of the most important water resources in sub-Saharan Africa from both a water supply and hydro-power generation perspective. Study focus: Calibration of two hydrological models (Pitman and WEAP) that have been established for 76 sub-basins covering the total basin area of about 1 350 000 km2. The longer-term purpose of establishing the models is to facilitate scenario analyses of future conditions related to changes in water use and management as well as climate change. New hydrological insights for the region: While there are many (inevitable) uncertainties in the data used, as well as the models and calibrated parameter sets themselves, the results suggest that the models are generally fit for purpose in terms of evaluating future changes. There are, however, some parts of the basin where the reduction of identified uncertainties would lead to improved models and greater confidence in their future use. One of sources of uncertainty relates to the existence of several large wetland areas that have impacts on downstream flows, but are difficult to simulate due to the relatively poor existing understanding of the dynamics of water exchange between the river channels and the wetland storage areas.
- Annex 10: Hughes D. and Farinosi F. , 2020. Assessing development and climate variability impacts on water resources in the Zambezi River basin. Simulating future scenarios of climate and development. ACEWATER2 report JRC120957 (Main deliverable)
Study region: The Zambezi River basin, a transboundary basin supplying vital resources to vast human and environmental systems and subject to radical changes linked to climate and infrastructural development.
Study focus: Application of a hydrological model (Pitman) established for 76 sub-basins covering the total basin area of about 1 350 000 km2 to assess the potential impacts of increasing water demand under global warming scenarios (1.5, 2, and 3 degree).
New hydrological insights for the region: The application of the calibrated model to the analysis of different combinations of climate change and water use showed that the relative impacts are quite different across the whole Zambezi River basin. The greatest impacts are found in the areas containing large open water bodies (natural and man-made), that are very sensitive to the multiple effects of increased aridity. The uncertainty in the future simulation results remains hugely dependent upon the source of the climate change data and the change signals given by them. The sample RCM data (6 models) used are representative of many more model outputs, while the spread of possible climate change signals remains quite large. However, the main uncertainties do not invalidate the overall message of possible water resources change that is summarized in a substantial decrease in water availability under all the combined scenarios.