Morphometric indicators for erosion and debris flows propagation: a case study of the river Byuyukdere watershed, northwest of Kardzhali town (Bulgaria)

Morphometric features of the topographic surface are one of the main prerequisites (conditioning factors) for the occurrence of erosion and debris flows. The following morphometric parameters of the river Byuyukdere watershed were calculated in the current study: basin area, basin relief, basin length, relief ratio, Melton’s index, slope and stream power index. The analysis shows higher susceptibility to erosion and debris flows of the 1st and 2nd order basins (Strahler’s method). The elevated values of the stream power index indicate an intensive erosion in the lower part of the river Byuyukdere watershed, which is related to the volcanogenic-sedimentary rocks and the faulted nature of the river valley. The morphometric analysis was performed in ArcGIS Pro on the base of a 12.5 m resolution digital elevation model.