Increasing the water level accuracy in hydraulic river simulation by adapting mesh level elevation

2D hydraulic models are one of the tools to simulate water levels for effective river management. Mesh resolution in 2D models directly impacts the discretization of the bathymetry, the discharge capacity, and consequently, the accuracy of simulated water levels. The objective of this study is to develop a modified mesh setup that corresponds with the cross-sectional flow volume of the measured cross-section but with a low resolution for the entire discharge range. An algorithm is developed to vertically adjust mesh nodes within a limited range to achieve this objective. Subsequently, the D-Flow-FM software is utilized to model four hypothetical 100-kilometer river reaches to evaluate the modified mesh setup. The findings reveal that the water level using the modified low-resolution mesh is up to 90% closer to the high resolution mesh compared to the original low-resolution mesh for all discharges. Additionally, the simulation of the low-resolution mesh runs approximately 12.5 times faster than their high-resolution counterparts.