Runoff formation in a catchment with Peat bog and Podzol hillslopes

Abstract Hydrological behavior of an ombrogenous raised peat bog has been observed and described in many studies; however, not in complexity with other soils. This research deals with the hydrological function of peat bog in a catchment where peat bog (formed by Histosol or other hydromorphic soils) covers only a part of the area (40–60%). Two soil types, creating two main hillslopes of the experimental catchment in this study, form the dominant soil types (Podzol and Histosol) in the Sumava Mountains, Czechia. A modified HBV model was used to estimate the contribution of each soil type to common outflow and for the estimation of the water balance. According to previous research and field observations, dominant hydrological processes were described for each hillslope (soil). The HBV model was used for the quantification of a ratio between fast and slow flow at Peat bog hillslope and Podzol hillslope. At Peat bog hillslope, the majority of outflow (67%) was formed from the upper soil layer (Acrotelm). In the mineral soil hillslope, a larger portion of runoff was generated from the lower soil layers or bedrock interface (61%). Peat bog contributes to a stream mainly during rainfall events; however, the model showed also significant deep percolation at the Peat bog hillslope and considerable contribution to baseflow during a year. Generally, more precipitation water was turned by the model into runoff at the Peat bog hillslope, which was also exhibited by a lower rate of actual evapotranspiration (21% of precipitation), compared to 29% in the case of Podzol hillslope. If we consider land-use changes in this locality in terms of expanding or reducing peat areas (draining, drains damming, droughts, etc.), this model could sufficiently estimate the hydrological behavior of local streams and thus can be potentially used in hydrological planning by local authorities.