14 December 2020
Within the context of Integraal Riviermanagement (IRM), Rijkswaterstaat (RWS) aims to create a one-dimensional morphodynamic model of the Meuse River between Eijsden and Keizersveer. This report describes the setup and calibration of this model. The purpose of the model is to simulate the long-term morphological development of the Meuse river bed both in response to human intervention and resulting from boundary forcing. The model is set up in the new D-HYDRO software suite (dflow1d).
Three models were built: representing the state of the river system in 1995 (j95), 2011 (j11) and 2019 (j19). All models were derived from the current 5 th generation hydrodynamic SOBEK models but were simplified to allow for stable and fast morphological simulation. The conversion steps and choices are described in detail in this report. The models were tested in two steps. First, the flow velocity, discharge distribution between main channel and floodplain, and water levels were compared with 2D model simulations. The 1D model main channel flow velocities compared favourably to 2D main channel flow velocities – which is most important for morphological simulation – using a uniform constant roughness value of 0.035 sm -1/3 . Water levels are generally overestimated by the 1D model compared to the 2D model.
Second, the morphological models are tested on annual sediment transport rates, bed level change over a period of 17 years, and celerity of bed disturbances. The ground truth data for these comparisons are based on a review of literature and available sounding data. Because the ground truth data was found to exhibit significant uncertainty, the morphological models were tested on their ability to simulate overall trends and correct orders of magnitude. We found that a combination of two sediment transport formulas (Meyer Peter Muller for coarse material; Engelund-Hansen for fine material) resulted in the best results. Both the annual sediment transport-load as well as the celerity of bed disturbances were found to be simulated within bounds suggested by literature. The overall trends in bed level change compare favourably with data.
The model is available here. Check how to access it in the download page.
dr. ir. K.D. (Koen) Berends
Researcher and Advisor, River Dynamics and Inland Waterways