The paper presents an approach to the modelling of watercourses or their sections according to and in order to determine their suitability for hydropower water use on a large scale. The method is based on a multi-criteria analysis approach which in addition to existing guidelines defines and describes in detail the main stages for model establishment and hydropower suitability analysis. Since hydropower planning stands in direct conflict with other ecological water-related objectives, evaluation of suitability is based on two main criteria, which are supported with the belonging criteria. The first main criterion is based on evaluation of watercourses by their attractiveness for hydropower water use; the second one on evaluation of watercourses according to their ecological state or value. To support proper determination of unknown model parameters (e.g. weights of selected criteria) the paper also presents an upgrade of general multi-criteria analysis process with a calibration stage, which can efficiently upgrade in cases when calibration data is available. The proposed method was tested and discussed on a real case study with three dislocated Slovenian Alpine watercourses, where weights of preselected criteria and some thresholds of performance functions were selected as model variables and calibrated.