Deep Waters: How ignoring uncertainty in hydrological modelling increases water security risk

Hydrological modelling informs critical decisions in water resource management in South Africa. Hydrological models take inputs of climate data and catchment properties and apply mathematical algorithms to approximate catchment processes, such as evapotranspiration, groundwater storage, and runoff generation. These models, some of which are locally developed, are used to estimate streamflow for ungauged catchments and to predict flows under different scenarios of climate, land cover, or management (Box 1). They provide needed inputs for yield models of reservoirs and supply systems, flood models, and water quality models.