A debris flow calendar derived from sediments of lake Lago di Braies (N. Italy)

In this study lake sediments were used for developing a high resolution calendar of past debris flow events. Debris flows frequently occur in the high-alpine catchment of the lake Lago di Braies (N. Italy). While the coarse grained material accumulates on the debris flow cones, the fine grained material is flushed into the lake. This material forms characteristic layers in the lake sediments, which are different from the typical annual lamination. By analysing thin sections of sediment, debris flow events of the last 2250 years were reconstructed with an annual resolution. Since debris flow frequency varies strongly, periods with high and low frequencies can be distinguished. However, neither a debris flow magnitude–frequency relationship nor a strong reaction of debris flow activity to past climate changes was identifiable in this study.