Evaluation of a data-based hydrological model for simulating the runoff of medium sized Andean basins

Using timeseries of rainfall and streamflow of two basins in the Andean mountain range, South Ecuador, different in size (300 and 1260 Km2), a generalized lumped conceptual model (VHM), offering the possibility of using different levels of complexity with number of model parameters varying between 5 and 15, was tested. To increase the information timeseries of total streamflow were split in timeseries of quick, intermittent and baseflow, and the timeseries were discretized to select independent events of high and low flows. The paper outlines in detailed the procedure for the model structure identification, calibration and validation, as well as the multi-objective criteria approach used to evaluate the performance of the model and its components. It has been shown that the model structure, consisting of a module for soil storage and quick flow, was able to model for both basins the water balance and streamflow components with acceptable accuracy. A low value of the soil water storage facilitates the model calibration but it is not a guarantee that the model performs better. The study further reveals that the risk of over-parameterization and associated uncertainty reduces strongly the more simple the structure of the model.