Spatial distribution of channel heads in the Polish Flysch Carpathians

One of the key topics in modern geomorphology is the identification of locations where the drainage network begins. However, there still exists a gap in the research literature in the area of channel head location in flysch regions characterized by unique hydrogeological conditions. In this study, we have identified the spatial distribution of channel heads and determined threshold values of morphometric parameters for catchments contributing to channel heads in the Polish Flysch Carpathians. We surveyed a total of 401 channel heads on the main ridge of the Połonina Wetlińska Range using GPS. The DEM was used to identify 16 physiographic parameters for each catchment, and statistical correlations between catchment parameters were also calculated. We compared field data versus the drainage network produced using a topographic map and DEM. The channel head density based on field mapping is five times higher than the density estimated using a topographic map, and 250% lower than that obtained from a DEM. Most channel heads are recharged by very small catchment areas. The threshold value for catchment size has been shown to be about 0.01 km2. The mean slope gradient responsible for channel head formation is 18° in the study area. Given the very small size of catchment areas contributing to channel heads in the study area, remote sensing methods are not useful. Fieldwork is still the best method of mapping channel heads. The distribution of channel heads across the Połonina Wetlińska Range in the Polish Flysch Carpathians cannot be described using simple relationships. Correlations between topographic attributes that are common in other physiographic regions are not very clear in flysch areas.