Regional Climate Models (RCMs) offer significant improvements over Global Cli- mate Models in terms of their representation of rainfall at the spatial and temporal scales required for hydrological modelling. Here we test a new implementation of a grid-based hydrological model embedded in a model of land-surface climatology (the Joint UK Land Exchange Scheme; JULES) against observed river flows in sev- eral major NW European rivers, including the Rhine, Maas, Elbe, Danube, Loire, and Seine. Our hydrological model includes a probability-distributed model of soil mois- ture and runoff production (PDM) coupled with a discrete approximation to the one- dimensional kinematic wave equation to route surface and subsurface water downs- lope (G2G). The model was driven with hourly output from the Hadley Centre regional climate model, using results from the ERA-40 reanalysis experiment as boundary con- ditions (1961-2000). The results of simulations for river catchments in northwest Eu- rope are presented and compared with measured river flows over the same time period, for the same locations. The success with which the runoff production and flow routing components of the land-surface model match observed flow data is evaluated
