Terminology, metrics and classification

Group Leader: Nicola Surian

The aim of the working group is to make a critical review of terminology, metrics and classification used in braided rivers. This will imply a detailed review of the state of the art, but also discussion about what terminologies, metrics, and classifications are more appropriate and what, eventually, should be avoided. Definition of common terminology and metrics will allow more reliable comparisons of data coming from different studies and to build large datasets on braided rivers. Common terminology, and classification, will facilitate also communication among scientists. Besides benefits for the scientific community this will be useful also for practitioners. This means that the final products of this working group could be not only scientific papers but also practical guidelines to work on braided rivers.

A preliminary summary on how to address the different topics is given below.

Terminology – Aspects to be addressed: which terms are used to described braided river morphology and processes? Are those terms appropriate or other terms are needed? Do authors give the same meaning to terms? For instance, as for the latter issue, “active channel width” is not used with the same meaning by different authors (e.g. Ashmore et al., 2011; Belletti et al., 2012).

Metrics – Features of braided rivers (e.g. channel width, braiding intensity, islands) have been measured in different ways in the past, but rarely a critical analysis of these metrics was carried out. A good example in this direction is the work by Egozi and Ashmore (2008) on braiding intensity. Besides, new metrics are now available due to recent technologies (e.g. Terrestrial Laser Scanning). Aspects to be addressed: which are the most relevant features to measure in a braided river? Which are the critical aspects related to those measurements (e.g. data source, errors associated with measurements)?

Classifications – Though each stream classification may have some limitations, we should recognized that classifications are needed and useful for different reasons, last but not least a clear communication among people (i.e. scientists and practitioners). Aspects to be addressed: which braided stream types have been defined in the past? Have such types be defined precisely or in a more qualitative way (e.g. distinction between “bar braided stream” and “island braided stream”)? How differences between gravel and sand braided rivers should be taken into account? Do classifications make a clear distinction between braided channel morphology and other channel morphologies such as anabranches and wandering?

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