The impact of overgrazing on water fluxes in a semi-arid watershed – The suitability of watershed scale modeling in a data scarce area

South Africa. This study focuses on the impact of overgrazing on the water resources in a semi-arid catchment in South Africa. We have applied the SWAT+ model to a data-scarce area. During the modeling process, hydropedological principles were applied in model parameterization and analysis of simulation results to identify areas which are sensitive to overgrazing. The scenario analysis indicates that overgrazing might not necessarily have a large impact on the water balance of the whole watershed, but may have negative impacts at the local subbasin scale. These impacts are increased surface runoff and evaporation which are the consequence of compaction of topsoils. The application of hydropedological principles in the analysis of simulation results help to identify areas sensitive to overgrazing. Shallow soils, soils with low surface infiltration capacities and hydromorphic soils are vulnerable to adverse effects from overgrazing. •Overgrazing might not have a large impact on the water balance at the watershed scale, but may have negative impacts at the local scale.•Impacts of overgrazing are increased surface runoff and evaporation.•Hydropedological principles can help to overcome data scarcity to improve modeling efficiency.