Preprints
https://doi.org/10.5194/esurf-2021-98
https://doi.org/10.5194/esurf-2021-98
 
20 Dec 2021
20 Dec 2021
Status: a revised version of this preprint is currently under review for the journal ESurf.

Short communication: A new tool to define multiscale bedform characteristics from bed elevation data

Judith Zomer, Suleyman Naqshband, and Ton Hoitink Judith Zomer et al.
  • Department of Environmental Sciences, Hydrology and Quantitative Water Management Group, Wageningen University & Research, Wageningen, Netherlands

Abstract. Systematic identification and characterization of bedforms from bathymetric data are crucial in many studies focused on fluvial processes. Automated and accurate processing of bed elevation data is challenging where dune fields are complex, irregular and, especially, where multiple scales co-exist. Here, we introduce a new tool to quantify dune properties from bathymetric data representing multiple dune scales. A first step in the procedure is to decompose the bathymetric data based on a LOESS algorithm. Steep dune lee side slopes are accounted for by implementing objective breaks in the algorithm, accounting for discontinuities in the bed level profiles, often occurring at the toe of the lee side slope of dunes. The steep lee slopes are then approximated by fitting a sigmoid function. Following the decomposition of the bathymetric data, bedforms are identified based on zero-crossing, and the relevant properties are calculated. The approach to decompose bedforms adopted in the presented tool is particularly applicable where secondary dunes are large and thus filtering could easily lead to undesired smoothing of the primary morphology. Application of the tool to two bathymetric maps demonstrates that the decomposition and identification are successful, as the lee side slopes are better preserved.

Judith Zomer et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on esurf-2021-98', Anonymous Referee #1, 05 Feb 2022
  • RC2: 'Comment on esurf-2021-98', Ray Kostaschuk, 11 Mar 2022
  • AC1: 'Comment on esurf-2021-98', Judith Zomer, 14 Apr 2022

Judith Zomer et al.

Model code and software

MATLAB code - Bedform Separation and Identification J. Zomer https://github.com/j-zomer/BedformSeparation_Identification

Judith Zomer et al.

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Short summary
River beds are often composed of different scales of dunes, who’s size and shape is highly variable over time and space. Characterization of these dunes is important in many research studies focused on fluvial processes. A new tool is presented here that aims to identify different scales of dunes from river bed elevation maps. A first step is to separate two scales of bedforms, without smoothing steep slopes of the larger dunes. In a second step, dunes are identified and properties are computed.