Parameterisation and application of a hillslope hydrological model to assess impacts of a forest clear-cutting on runoff generation

This paper combines results of an empirical paired-catchment method and hydrological simulation techniques in quantifying and explaining the effect of a clear-cutting on runoff generation. The pair of catchments (56 and 24 ha) is located in the middle boreal zone in Eastern Finland. In the first part, measured runoff from the two catchments, of which one had been partly clear-cut (35%) and the other had not been treated (control), was analysed to detect differences in runoff preceding and following the cutting. In the next part, snow and canopy models were calibrated against snow water equivalent data in an open and forested environment, respectively. Output from the canopy and snow models provided an input to a hillslope hydrological model, which was parameterised for the two catchments and calibrated against runoff measurements. The hydrological model was applied to identify mechanisms that could explain the observed difference in the hydrological behaviour of the two catchments. According to the model results, both the decreased interception in the clear-cut catchment and the increased evapotranspiration in the young, growing forest in the control catchment contributed to the observed differences in spring flood volumes. During the growing season, most of the change in runoff generation between the catchments was attributed to the increased evapotranspiration in the young forest.