Processes Towards Sedimentation around a Reed Island in a Shallow Lake

Authors

  • Mariann Biró-Szilágyi
    Affiliation
    Department of Hydraulic and Water Resources Engineering, Faculty of Civil Engineering, Budapest University of Technology and Economics, H-1111 Budapest, Műegyetem rakpart 3., Hungary
  • Tamás Krámer
    Affiliation
    Department of Hydraulic and Water Resources Engineering, Faculty of Civil Engineering, Budapest University of Technology and Economics, H-1111 Budapest, Műegyetem rakpart 3., Hungary
    National Laboratory for Water Science and Water Safety, Budapest University of Technology and Economics, H-1111 Budapest, Műegyetem rakpart 3., Hungary
  • Krisztián Homoródi
    Affiliation
    Department of Hydraulic and Water Resources Engineering, Faculty of Civil Engineering, Budapest University of Technology and Economics, H-1111 Budapest, Műegyetem rakpart 3., Hungary
    National Laboratory for Water Science and Water Safety, Budapest University of Technology and Economics, H-1111 Budapest, Műegyetem rakpart 3., Hungary
https://doi.org/10.3311/PPci.22380

Abstract

There are many studies on the hydromorphological impacts of emergent aquatic vegetation, but many of these focus on gravity-driven flows in riverine or tidal environments. However, an added effect of emergent vegetation in lakes is that it reduces the main external force (wind) significantly and in a spatially coherent way. We performed long Monte Carlo simulations using a 2D hydrodynamic model and a spectral wind wave model to study resuspension dynamics around a 100-m-wide reed island in southern Lake Fertő/Neusiedl. Wave-current interaction, computed in a post-processing step, was found to enhance maximum bed shear stresses only on the leeward side of the reed island, and even there to a small extent. We have found evidence that the present bed topography is close to an equilibrium where simulated combined wave-current shear stresses have a reasonably uniform exceedance probability over the critical shear stress of the bed sediment. We also found that an artificially flattened lakebed around the reed island would start evolving towards the present bed topography and grain size distribution (both of which were surveyed in the field). Despite the limitations of our modelling framework, our results illustrate the importance of how wind climate is translated to an uneven distribution of sediment entrainment around the reed island, explaining tendencies of sediment accumulation and sorting. Our results lead to a better understanding of the complicated processes involving interaction among wind, vegetation, circulation, wind waves, sediment and bathymetry.

Keywords:

emergent vegetation, lake hydrodynamics, bed shear stress, simulations, field observations

Citation data from Crossref and Scopus

Published Online

2024-01-02

How to Cite

Biró-Szilágyi, M., Krámer, T., Homoródi, K. “Processes Towards Sedimentation around a Reed Island in a Shallow Lake”, Periodica Polytechnica Civil Engineering, 68(2), pp. 459–468, 2024. https://doi.org/10.3311/PPci.22380

Issue

Section

Research Article