12 Jul 2023
 | 12 Jul 2023

Benthos as a key driver of morphological change in coastal regions

Peter Paul Arlinghaus, Corinna Schrum, Ingrid Kröncke, and Wenyan Zhang

Abstract. Benthos has long been recognized as an important factor influencing local sediment stability, deposition and erosion rates. However, its role in long-term (annual-to-decadal scale) and large-scale coastal morphological change remains largely speculative. This study aims to derive a quantitative understanding of the importance of benthos in the morphological development of a tidal embayment (Jade Bay), as representative for tidal coastal regions. To achieve this, we firstly applied a machine learning-aided species abundance model to derive a complete map of benthos (functional groups, abundance and biomass) in the study area, based on abundance and biomass measurements. The derived data were used to parameterize the benthos effect on sediment stability, erosion/deposition rates, and hydrodynamics in a 3-dimensional hydro-eco-morphodynamic model, which was then applied to the Jade Bay to hindcast morphological and sediment change for 2000–2009. Simulation results indicate significantly improved performance with benthos effect included. Results suggest that the model is able to reproduce the main pattern of morphological change only when benthos impact is included, whilst abiotic drivers (tides, storm surges) alone would lead to an opposite pattern. Based on comparison among scenarios with various combinations of abiotic and biotic factors, we further investigated the level of complexity of hydro-eco-morphodynamic models that is needed to capture long-term and large-scale coastal morphological development. The accuracy in parametrization data was crucial for increasing model complexity. When the parametrization uncertainties were high, increased model complexity decreased model performance.

Peter Paul Arlinghaus 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 egusphere-2023-1303', Matthew Hiatt, 16 Aug 2023
    • AC1: 'Reply on RC1', Peter Arlinghaus, 21 Sep 2023
  • RC2: 'Comment on egusphere-2023-1303', Anonymous Referee #2, 18 Aug 2023
    • AC2: 'Reply on RC2', Peter Arlinghaus, 21 Sep 2023

Peter Paul Arlinghaus et al.

Peter Paul Arlinghaus et al.


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Short summary
Benthos is recognized to strongly influence sediment stability, deposition/erosion. This is well studied on small scales, but large scale impact on morphological change is largely unknown. In this study we quantify the large scale impact of benthos by modeling the evolution of a tidal basin. Results indicate profound impact of benthos by redistributing sediments on large scales. As confirmed by measurements, including benthos significantly improves model results compared to an abiotic scenario.