Formation conditions and evolution property of debris flow resulting from Glacier Lake Outburst Floods in Tibet

The GLOFs could not form debris flow at the beginning of moraine dam failure, because the discharge are very big and there are not sufficient loose materials to evolve to debris flow in the breach. Whether the GLOFs could evolve to debris flow or not depend on average gradients in the “U” ship glacier gully and the magnitude of old tills, outwash materials and landslide or rock avalanche, and whether there are rapid erosive process, if the width of gully do not sharply change (Lv et al. 1999).