In addition to the climate scenarios based on GCM data, further scenarios were defined for climate sensitivity analysis. Observed climate data of the period 1961–1990 were modified by increasing/decreasing precipitation by 10%, as well as increasing temperature by +2 °C and +4 °C. Again the same development as in the Baseline scenario
was used. For the sake of brevity and clarity we do not present scenarios that are combinations of different levels of development and climate projections. One obvious combination would be to assess the impact of Moderate development in conjunction with climate model projections for the near future. PI3K signaling pathway However, the current climate model projections are highly uncertain which we show in the results section. Therefore, little could be learned from additional scenario combinations. First we report on the simulation results for discharge under Selleckchem NU7441 historic conditions
and the related performance of the river basin model. Subsequently, results of the scenario simulations for the pre-defined development and climate change scenarios are presented. This section gives insights into the historical hydrological conditions of the period 1961–1990 in the Zambezi basin, as observed and modelled. Fig. 5 shows a comparison of simulated and observed monthly hydrographs for the Upper Zambezi River at Victoria Falls and the Zambezi River at Tete. With the exception of a few years, the simulated discharge closely matches the observed discharge at Victoria Falls. The differences are larger for the simulation of discharge at Tete, but still the general characteristics are simulated well. From Fig. 5 it is clear that the hydrograph at Victoria Falls represents undisturbed river flows with typical seasonality, whereas the hydrograph at Tete is impacted by the operation of the large Kariba and Cahora Bassa reservoirs. For example,
during the 1980s there was no typical seasonality in discharge due to constant releases from Kariba reservoir in dry periods and flood attenuation in wet periods. Tau-protein kinase From 1975 to 1977 the simulations deviate considerably from the observed discharge. During this period Cahora Bassa reservoir was first filled and the operation rules imposed on the model do not reflect the actual operations in this period well. During the 1980s water levels in Cahora Bassa reservoir were affected by the armed conflict in Mozambique. The reservoir was not run with normal operations from 1981 to 1998 because transmission lines from the hydropower plant were destroyed. The simulation of the operation of Kariba reservoir – which is the largest reservoir in the basin and twice as large as Cahora Bassa – is evaluated next. Fig. 6 shows a comparison of simulated and observed water levels. Kariba dam was completed in 1959 and the filling of the reservoir lasted until 1963, which is simulated well (Fig. 6, left side).