South Africa, Republic of [Applications of Isotope-Enabled Hydrological Models]

This study focused on validating the simulated hydrological processes and the flow component separation ability of the distributed JAMS/J2000iso rainfall-runoff model of the Berg River catchment, which forms the basis of a future climate vulnerability assessment. While JAMS/J2000iso simulates small scale processes and flow dynamics at a hillslope scale, its groundwater and aquifer properties are more conceptual which affects 'plausible' model parameter combinations. Sampling of rain, stream, groundwater isotopes were taken between the periods 2020 to 2021 on a weekly basis and aggregated. A binary mixing model was used to determine the fractional water content of surface runoff and baseflow in the lower reaches and used for comparison purposes with the simulated flow components. The choice of 'plausible' model parameters relied on selecting parameters which gave a similar flow component breakdown using the fractional contribution of each of the water isotopes.