INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
Spatiotemporal analysis of channel wall erosion in ephemeral torrents using tree rootsAn example from the Patagonian Andes
STOFFEL, M.; CASTELLER, A.; LUCKMAN, B.H.; VILLALBA, R.
GEOLOGICAL SOC AMER, INC
Lugar: Boulder; Año: 2012 vol. 40 p. 247 - 247
This paper presents absolute ages for flash floods and related sediment entrainment in headwater catchments to construct a spatiotemporal framework of process dynamics and locations of major areas of channel wall erosion. The most reliable method for datingerosion is through dendrogeomorphic studies of exposed tree roots. Based on the analysis of erosion signals in root-ring records we documented a time series of channel wall erosion and successfully dated 21 erosive fl ash fl ood events since A.D. 1870 in an ephemeral gully in the Patagonian Andes. The study was performed with roots from Austrocedrus chilensis, Nothofagus dombeyi, and Pseudotsuga menziesii. Results demonstrate the potential of root analyses for the determination of major areas of sediment entrainment. In addition, we show that the position of damage within individual root rings allows inferences about the seasonal timing of fl ash flood effects and thus an assessment of possible meteorological triggers of erosive events, short intense storms occurring primarily in austral fall and late winter in this case. The approach presented adds significantly to the documentation of sediment entrainment and facilitates identification of areas of rapid erosion in small, remote headwater catchments with ephemeral fl ash flood activity.