Zróżnicowanie spływu powierzchniowego i spłukiwania gleby na poletkach doświadczalnych o różnej długości (Szymbark, Beskid Niski)

The study on soil wash was conducted on the experimental slope within the Scientific-Research Station of the Institute of Geography and Spatial Organization (Polish Academy of Sciences) in Szymbark in years 1990-96. Five experimental plots installed on the slope were 2m wide, had lengths of 2, 4, 8, 16, and 32m and were under black fallow. Measurements of overland flow and soil wash reveled relationships between the processes and lengths of the plots and sums and intensity of rainfall events. The volume of the surface flow increased with increasing length of the plots, from 3352 dm³ (2m) do 12153 dm³ (32m), but on the other hand this was accompanied by decrease in the flow index. The index value was highest on the shortest plot (2 m) - almost 5 times greater than on the 32m-long plot. The observed relationship is typical for the river catchments: the smaller the catchment, the higher the flow index is (pertaining to 1 km² of the area). The soil wash occurred to be more differentiated with respect to the length of the plots (from 131,6kg to 1166,4kg). The relationship between maximum intensity of rain and soil wash on all plots has a character of polynomial equations of the second degree, described by negative correlation coefficients. As the plot's length increases, the relationship is stronger. During rainfall events of a very high intensity, over 1,5 mm min⁻¹ (high kinetic energy), the soil wash is limited by aggregating soil particles due to action of the rain droplets. Agrotechnical treatments significantly influence the process of soil relocation (weeding, ploughing). Observed soil wash directly following such treatments was much more intensive in comparison with conditions of slightly compressed soil.