Morphodynamic model of the Meuse River : Linne - Roermond v0.5, Roermond - Belfeld v0.5, Belfeld - Sambeek v0.5, Grave - Lith v0.5, Lith - Keizersveer v0.5

The Meuse River at present does not have a validated numerical model for morphodynamics. To uniformise the approaches on the Rhine and the Meuse, a plan was developed for the construction of a two-dimensional morphodynamic model of the Meuse which builds on the recently developed hydrodynamic D-HYDRO model of the Meuse. Transition to D-HYDRO, is desired, since it is foreseen that the new hydrodynamic model will replace the current WAQUA hydrodynamic model in the future.The hydrodynamic model includes the Meuse from Lixhe to Keizersveer. In 2021, a pilot reach in the Common Meuse (in Dutch: Gemeenschappelijke Maas, also Grensmaas) was identified near Meers. In past years, the location of Meers was modelled by carrying out multiple simulations. Also, the reach of Sambeek-Grave was selected as a second pilot location.This document describes the preliminary construction of five submodels covering thefollowing reaches of the River Meuse: i. Linne - Roermond v0.5 ii. Roermond - Belfeld v0.5 iii. Belfeld - Sambeek v0.5 iv. Grave - Lith v0.5 v. Lith - Keizersveer v0.5 At this early stage of model development for the five reaches, no calibration has been conducted yet. The initial outcomes are derived using the same morphological and sediment transport settings as employed in the pilot model of the Sambeek-Grave case study. Hydrodynamic simulations were conducted using steady discharges for a schematized discharge hydrograph. From these simulations, the yearly sediment transport per kilometre was obtained and visually represented. These graphs demonstrate the initialsediment transport gradient, which dictates whether erosion or deposition will occur. Analyzing these graphs enables adjustments to be made to the input parameters — both hydraulic and morphological — to more accurately reflect the measured conditions. Initial morphological computations covering a 4-year span (2014-2018) have been conducted. The temporal evolution of the bed level is visually presented, aiming at the assessment of input accuracy and model stability. However, these runs are not yet suitable for evaluating the model’s accuracy as the model inputs require adaptation. These preliminary model results offer insights and recommendations for adjusting the model inputs, aimed at enhancing model stability, refining the initial sediment transport and its gradients, and improving the morphological outcomes.Various challenges have emerged during the development of these submodels. This report addresses these challenges and provides recommendations for further development of these models.