Source: Journal of Geophysical Research: Earth Surface
Topographic analysis, that is, the analysis of landscapes using topographic data, is a powerful tool with a wide range of applications including mapping, tectonic geomorphology, and natural risk assessment. High-resolution topographic data (such as lidar) is becoming increasingly available, but the traditional methods used to extract channels and identify process domains (e.g., hillslopes, channels, floodplains) are not always suitable for the analysis of such data. In particular, traditional flow routing methods tend to extract channels as one pixel wide lines, which is problematic when channels are wider than one pixel. The latter can occur when the resolution of the topographic data is high (e.g., lidar data with ≤ 1 m resolution) or where channels are very wide.
Bernard et al.  provide a new simple approach that solves these problems. They show that running a 2D hydraulic simulation allows a better delineation of channels and hillslopes (see figure above), and propose new hydro-geomorphic metrics that provide very rich information on the different process domains (channels, hillslopes and floodplains) and their dynamics. The method allows to reliably measure channel width, to discriminate confined and unconfined channels, and to better understand the impact of knickpoints (waterfalls) on channel-hillslope coupling.
High-resolution topographic data are revolutionizing the way we analyze landscapes: they contain a wealth of information, but methods to reliably extract some of this rich information are lacking. This work unlocks this potential and provides a unique framework for future topographic analyses.
Citation: Bernard, T. G., Davy, P., & Lague, D. (2022). Hydro-geomorphic metrics for high resolution fluvial landscape analysis. Journal of Geophysical Research: Earth Surface, 127, e2021JF006535. https://doi.org/10.1029/2021JF006535
—Mikaël Attal, Editor, Journal of Geophysical Research: Earth Surface