State of debris flow research on the western slopes of the Keprnická hornatina (the Hrubý Jeseník Mts.)

The debris flows are fast dangerous processes initiated also in mid-mountains of the Czech Republic, frequently damaging forest stands. An occurrence of debris flows in the Hrubý Jeseník Mts. is connected with steep slopes and high-gradient channels predisposed by landuse, morphometric, lithological and especially climatic conditions. The first stage of research was implemented in the Klepáčský brook drainage basin. In 2013, a field geomorphological mapping and sampling of disturbed trees for dendrogeomorphic research (tree ring analysis) were carried out. There are preserved several remnants of former debris flows. The oldest accumulations in a form of terraces above the channel bottom, younger but stable and overgrown lateral levees and recent fresh frontal lobes directly in the channel were distinguished. At least 9 debris flow events in the last 60 years were dated in the Klepáčský brook from the tree ring analysis; the year 2010 was the last known and the most represented period in the tree ring series. Spatial dimensions, magnitudes of debris flows and places of their origin has been changed during the last decades so we could analyze their different behaviour patterns (e. g. 1991, 1997 and 2010), recorded in disturbed trees along the brook. The research will be extended to other basins in the Keprnická hornatina Mts., focusing on factors of debris flow predisposition and chronology with an application of dendrogeomorphic methods being actually the most accurate approach for dating of events in far-flung tree-covered basins.The debris flows are fast dangerous processes initiated also in mid-mountains of the Czech Republic, frequently damaging forest stands. An occurrence of debris flows in the Hrubý Jeseník Mts. is connected with steep slopes and high-gradient channels predisposed by landuse, morphometric, lithological and especially climatic conditions. The first stage of research was implemented in the Klepáčský brook drainage basin. In 2013, a field geomorphological mapping and sampling of disturbed trees for dendrogeomorphic research (tree ring analysis) were carried out. There are preserved several remnants of former debris flows. The oldest accumulations in a form of terraces above the channel bottom, younger but stable and overgrown lateral levees and recent fresh frontal lobes directly in the channel were distinguished. At least 9 debris flow events in the last 60 years were dated in the Klepáčský brook from the tree ring analysis; the year 2010 was the last known and the most represented period in the tree ring series. Spatial dimensions, magnitudes of debris flows and places of their origin has been changed during the last decades so we could analyze their different behaviour patterns (e. g. 1991, 1997 and 2010), recorded in disturbed trees along the brook. The research will be extended to other basins in the Keprnická hornatina Mts., focusing on factors of debris flow predisposition and chronology with an application of dendrogeomorphic methods being actually the most accurate approach for dating of events in far-flung tree-covered basins