The Entropic Braiding Index (eBI): A Robust Metric to Account for the Diversity of Channel Scales in Multi-Thread Rivers

The Braiding Index (BI), defined as the average count of intercepted channels per cross-section, is a widely used metric for characterizing multi-thread river systems. However, it does not account for the diversity of channels (e.g., in terms of water discharge) within different cross-sections, omitting important information related to system complexity. Here we present a modification of BI, the Entropic Braiding Index (eBI), which augments the information content in BI by using Shannon Entropy to encode the diversity of channels in each cross section. eBI is interpreted as the number of effective channels per cross-section, allowing a direct comparison with the traditional BI. We demonstrate the potential of the ratio BI/eBI to quantify channel disparity, differentiate types of multi-thread systems (braided vs. anastomosed), and assess the effect of discharge variability, such as seasonal flooding, on river cross-section stability.

Automated summary

The Braiding Index (BI) is a widely used metric for multi-thread river systems, but it fails to account for the diversity of channels within different cross-sections, omitting important information related to system complexity. In this study, the researchers propose a modification called the Entropic Braiding Index (eBI) which uses Shannon Entropy to encode the diversity of channels, providing a more comprehensive characterization of the system. They demonstrate that the ratio BI/eBI can quantify channel disparity, differentiate types of multi-thread systems, and assess the effect of discharge variability on river cross-section stability.