Page 122 - CIWA Water Data Revolution Overview Report

have expanded by about 1.4% and 0.6% per annum on average over the past 25 years, and

now cover about 55 000ha and 367 000ha respectively.

3.12 Running the Water Accounting Plus Model for the Incomati and Maputo River Basins

The Incomati and Maputo SIWA+ model runs were conducted for the period 2003-2021 with

the first couple of years used for “model warm-up”. Outputs from the VegET model of (Akpoti

et al., 2024) served as input to the pixel-based water balance model. The model was used to
generate the water accounts for each basin under current conditions 2001-2021.

3.13 Summary WA Results for the Incomati Basin

The Incomati River Basin resource base sheet averaged for 2003 to 2021 and is presented in

Figure 6. For this period a number of indicators are calculated: the average annual rainfall

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over the basin was approximately 25.7 km /year, actual ET was 35.1 km /year, while the
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average annual flow out of the basin was 3.6 km /year. Overall, from 2003 to 2021, the basin
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is recharging surface and groundwater storage at an average rate of 8.6 km /year.