Methods for the Quantitative Assessment of Channel Processes in Torrents (Steep Streams)

An important part of the risk management of natural hazards in mountain regions concerns the hazard assessment and the planning of protection measures in steep headwater catchments, i.e. torrent control and slope stabilization. Torrent processes in steep channels have their rightful place among the various alpine natural hazards and the corresponding control measures have a long tradition in the European alpine countries. In the planning and execution of such measures, professional experience has been of paramount importance. This experience was based primarily on observations made during and after hazardous events, as well as on regular field visits in the catchments of a steep headwater stream. Quantitative measurements, e.g. of the discharge and of the eroded and deposited solid materials, have been increasingly carried out only in the last decades. This set the basis to develop and improve quantitative methods to predict flow hydraulics, bedload transport and debris flows in torrent catchments. This publication presents an overview of methods to quantify channel processes in steep catchments. The understanding and the quantitative description of channel processes provides an essential basis for the planning of protection measures.