Comparative evaluation of performances of different conceptualisations of distributed HBV runoff response routines for prediction of hourly streamflow in boreal mountainous catchments

Unidentifiability and equifinality of parameters pose challenges to calibration and prediction by conceptual precipitation-runoff models. Evaluation of prediction performances of parametrical parsimonious and more complex conceptualisations is lacking for hourly simulation. We conducted a comparative evaluation of four configurations of the distributed (1 × 1 km2 grids) HBV (Hydrologiska Byrans Vattenballansavdelning) runoff response routines for hourly streamflow simulation for boreal mountainous catchments in mid-Norway. The routines include the standard Swedish Meteorological and Hydrological Institute HBV or HBV-SMHI, HBV-non-linear (standard soil routine and non-linear reservoirs), HBV-Soil Parsim R (standard soil routine and linear reservoirs) and HBV-Parsim (parsimonious and linear soil routine and reservoirs). The routines provided simulated hydrographs, flow duration curves and quantile–quantile plots, which are marginally different from each other for the study catchments. However, the HBV-Parsim provided better parameter identifiability and uncertainty, and simulated baseflow that better matches the baseflow separated by filtering techniques. Performances of the HBV-Parsim indicated a potential for application of parametrical parsimonious routines, which would benefit model updating for forecasting purposes. The study revealed strong effects of the soil moisture (SM) parameters on the recharge, percolation and hence the baseflow, which substantiates the importance of evaluating the internal simulation (e.g., SM and baseflow) of the HBV routines against measurements or analytical computations.