Performance assessment of the semi-distributed hydrological model HYPE for central Norway
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Norway s water authorities need a comprehensive tool to generate hydrological infor-mation for all water bodies to implement the European water framework directive.The precipitation-runoff model HYPE was developed by the Swedish meteorologicalinstitute SMHI. In Sweden, it is used for flood forecasting, characterization of waterbody status and establishment of environmental goals. The model structure and thespatial assignment system of hydrological properties makes it suitable for predictionsin ungauged catchments.The main question for this thesis was to evaluate, if the semi-distributed model is asuitable simulation framework for Norway and if predictions for ungauged catchmentsare of satisfying accuracy.HYPE was applied and tested for Norway. The model was set up for a region of81,900 km 2 in central Norway and divided into ∼ 2500 sub-catchments. National databases for land use and soil types were combined to assign physiographical attributesto sub-catchments. 40 streamflow stations were implemented, the discharge timeseries of ten stations were used for calibration, validation and regionalization.HYPE was calibrated using a multi-basin approach, i.e. it was not calibrated toindividual stations but for optimal performance across a selection of five stream flowstations. Their respective drainage areas are unregulated and range in size from 100km 2 to 3000 km 2 . The model fitness was assessed with split-sampling for a period offive years. Kling-Gupta-efficiency (KGE) was applied as index of model performance.The regional calibration resulted in a mean KGE of 0.73 and 0.71 for the calibrationand validation period respectively.The model configuration was transferred to five independent proxy catchments withcomparable catchments characteristics. The model yielded a mean KGE of 0.49 forthe selected regionalization catchments. The regionalization was expanded to allimplemented gauges, resulting in a mean KGE of 0.51. Performance assessment ofthe ungauged catchments show a high variance in model fitness.