Behind every robust result is a robust method: Perspectives from a hydrological case study

Stringent modelling methods and diagnostic techniques for improving the credibility of model predictions have received a lot of attention in the hydrological literature. However, previous discussions have revolved mainly around theoretical aspects, and arguably lacked persuasive examples. In this work, in order to illustrate the weaknesses of widespread modelling practices, we instead provide an applied perspective. In particular, we present the case of a distributed rainfall-runoff model that evolves in response to progressively more stringent application of model diagnostics. Through this example we demonstrate the usefulness of the following methodological instruments: (i) benchmarking model results against a null-hypothesis model, (ii) testing model predictions in space-time validation, and (iii) carrying out controlled model comparisons. These instruments, arguably still underutilized in the hydrological community, offer important diagnostic capabilities to increase the rigor of hydrological and environmental model applications.  Therefore their more widespread application is encouraged.