Abstract
A model for quantitatively expressing the hydrological cycle in a forested mountain catchment is proposed as a HYCYMODEL. HYCYMODEL is able to predict both short‐ and long‐term hydrographs because the model parameters remain independent of time. It shows a good applicability for ten years of continuous data at both hourly and daily intervals for the Kiryu catchment—a forested mountain basin. Since HYCYMODEL does not need hydrograph separation between storm flow and base flow, it is a particularly attractive model.