Towards identifying sources of subsurface flow: A comparison of components identified by a physically based runoff model and those determined by chemical mixing techniques

A physically‐based semidistributed model, TOPMODEL, is applied to a 340 hectare spruce forested catchment in mid‐Wales. the model is calibrated to runoff and the subsurface flow is divided into components of flow identified by depth of origin. in addition, chemical mixing techniques are used to provide a hydrograph separation between acidic soil waters and well buffered deep waters. the short‐term variations in the components of flow identified by these two approaches compare well.