A diversity of hydrological and hydrochemical data is the foundation for an integrated modelling study of a leaching tailing deposit at Bersbo in southern Sweden. A distributed conceptual water balance model system combined with empirical hydrochemical subroutines are used to describe the variation pattern in runoff, alkalinity and pH of the outlet of the drainage basin. Examples of the sensitivity of the model output to perturbations of some of the model parameters are shown.