Modelling extreme flood hazard events on the middle Yellow River using DFLOW-flexible mesh approach

Abstract. Severe flooding events in China are a common cause of life losses. Many efforts have been carried out to understand flooding development and impact on the Yellow River. New approaches on modeling, specifically with the current development of the software modeling tool DFLOW-FMβeta gives the opportunity to enhance the understanding of the behavior of the Yellow River during extreme events. The modeling approaches based on discretization of the modeled domain in square and rectangular grids have a great importance in the management of rivers but usually they present two drawbacks: the required accuracy of the meandering of wide long rivers is not well represented, and the reduced speed in computational runtime due to the need of using many grid cells. A new tool, developed by Deltares, based on a flexible mesh discretization of the domain, presents the advantage that the two drawbacks can be overcome. The approach has the advantage of combining different grids, in order to properly represent the river and compute the flooding extent accurately. The method is checked and demonstrated on the Yellow River case. Along with the test of the new proposed modeling method new characteristics of the spatial flooding process in the Yellow River emerges and are presented in the paper, showing the capabilities of the software application tool in modeling such a complex environment like the one studied.