Several field experiments on debris were carried out at the Chemolgan test site in Kazakhstan. Artificial floods triggered the formation of debris flows with resulting solid concentrations by volume of more than 0.73. The volume of eroded and entrained sediments is related to the magnitude both of the initial water discharge and of the "hydraulic" load resulting from the sediment-laden flow, although the data show a considerable scatter. It appears that surges with a high sediment concentration tend to be less erosive than more fluid mixtures. Similar measurements were performed in a laboratory flume. The analysis of this data shows an even larger variability of the eroded volumes but on the whole results in similar trends.