A comparison of recharge estimates to a fractured sedimentary aquifer in South Africa from a chloride mass balance and an integrated surface-subsurface model
1996
Sami, K. | Hughes, D.A.
The paper describes the use of an integrated surface-subsurface modelling approach to estimate recharge to a semi-arid Karoo aquifer and a comparison of the results with a chloride mass balance on a sub-area scale. Parameters were not calibrated, to test the success with which the model can be applied in regions of scarce data. The chloride balance suggests a mean annual recharge of 4.5 mm year-1 based on a mean annual rainfall of 460 mm. The model predicts 5.8 mm year-1 from a mean annual rainfall of 483 mm during the simulation period. Recharge was found to be highly variable in space with a positively skewed distribution in time. Spatial variability was attributed to differences in the distribution of soil moisture content resulting from variations in slope, soil texture and depth. Both methods suggest that recharge is considerably less than the mean of 9.9 mm year-1 estimated from the currently prescribed rainfall-recharge relationship for Karoo aquifers.
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