Analysis of sediment from steps in a small catchment in the Polish Carpathians in relation to the transition zone between the hillslope and fluvial system

Abstract

An investigation to determine the transition zone between the hillslope system and the fluvial system in connection with the degree of differentiation of sediment located upstream and downstream of log steps (LS) and boulder steps (BS) was undertaken in the channel of a stream located in a small mountain catchment area in the Silesian Beskidy Mts. (Polish Carpathians), a stream channel into which large wood was introduced artificially several years ago. Granulometric analyses of 41 samples taken from upstream (21) and downstream (20) of steps were performed to analyze the effectiveness of log steps and boulder steps in the differentiation of mineral sediment.It was demonstrated that log steps have a significant impact on the functioning of the channel by shaping its longitudinal profile and affecting the transport of mineral material, whereas boulder steps retain less sediment, showing the beneficial effects of artificial creation of log steps in mountain stream channels. Results of granulometric analyses suggested the location of the theoretical transition zone between the hillslope system and the fluvial system, suggesting the location and range of this zone in small mountain catchment areas can change depending on the intensity and range of slope processes in the longitudinal profile of the channel.