Testing the distributed water table predictions of TOPMODEL (allowing for uncertainty in model calibration): The death of TOPMODEL?

Abstract

The distributed predictions of the original version of TOPMODEL are here compared with distributed observations of water table levels in the Uhlirska catchment in the Jizera Mountains, Czech Republic. The calibration of the model has been carried out within the GLUE framework, which allows the estimation of uncertainties in predicting the distributed patterns of the water table at different times. Many of the water table levels are predicted within the limits of uncertainty, but it is shown that the predictions could be improved by the calculation of a local effective transmissivity value (or local upslope contributing areas) at each observation site. These effective transmissivities show a similar relationship to the topographic index as found in a previous study of a small catchment in Norway. Some of the anomalies can be explained by deficiencies in the topographic analysis but this may also be an indication of possible structural deficiencies in the model. Interpretation is, however, difficult, and it remains to be seen whether these anomalies might be avoided in more dynamic distributed models.