Evaluation of a conceptual, semi-distributed hydrological model : a case study of Hörbyån

Abstract: Research in hydrological modelling has been directed towards the development of more complex models that may consider the spatial and temporal variations of meteorological and physical characteristics of a drainage basin. The aim with this study was to evaluate the HBV-model (Hydrologiska Byråns Vattenavdelning), a conceptual, semi-distributed hydrological model. This model is able to take the spatial distribution of meteorological and physical factors in a drainage basin into consideration. An attempt to investigate the possibilities to improve the calibration and validation results from the HBV-model were made by increasing the spatial resolution of physical and meteorological characteristics of Hörbyån’s drainage basin (located in Skåne, the southern part of Sweden). Hörbyån’s drainage basin was partitioned into five and ten sub basins. Area values of the precipitation, elevation and vegetation types (forest/open land) were calculated in every basin. Distributed information of soil types (sand/clay) was also considered with parameters for the soil moisture zone. The results were compared with calibrations and validations of Hörbyån’s drainage basin used as a single basin. The calibration and validation results in the HBV-model were improved when the spatial distribution of vegetation and precipitation were taken into account. The calibration results were slightly improved when elevation zones and soil types were considered in the model. However, to run the HBV-model when increasing the spatial resolution of physical and meteorological characteristics in a drainage basin was time consuming and the requirements of input data were large.