Author(s): Frederik Folke; Martin Hammerle
Linked Author(s):
Keywords: Vegetation; Airborne laser scanning; Roughness; 2d model; Telemac-2D
Abstract: Natural embankments and floodplains are characterized by the presence of species-rich vegetation providing an important habitat for other organisms. However, emerged and submerged vegetation can significantly alter the flow field leading to an increase in hydraulic resistance – especially during flooding events. The hydraulic influence of vegetation is currently mainly simulated in 2D models using empirical resistance coefficients such as Manning or Strickler, which can be determined using tables from the literature. This method is subject to major uncertainties and a certain subjectivity on the part of the user. Influences such as the ratio of flow depth to vegetation height or the influence of flexibility must be estimated a priori, as these effects are not mapped in the model. This method is no longer state-of-the-art to model vegetation-induced hydraulic resistance. Instead, vegetation approaches considering the underlying physical mechanisms should be used (e. g. Baptist et al., 2007; Folke, 2023; Box et al., 2023). Relevant vegetation parameters need to be collected as input data for the vegetation approaches. Simple and efficient methods for collecting vegetation parameters are therefore essential for large-scale applications. The aim of this study is to demonstrate the potential of current airborne laser scanning (ALS) data for deriving vegetation parameters even though originally collected for the creation of digital terrain models.
Year: 2024