Enhancing compound flood simulation accuracy and efficiency in urbanized coastal areas using hybrid meshes and modified digital elevation model

Abstract

Accurate flood simulation is crucial for comprehending its impacts, especially in urbanized coastal areas. Reliable flood modeling depends on precise input data, as errors can lead to inaccurate severity estimates. This research investigates the impact of Digital Elevation Model (DEM) modifications on hydrodynamic simulation results, particularly in densely populated urban regions where man-made features like roads and bridges significantly affect water movement. Findings reveal that integrating local survey data to modify DEMs not only significantly enhances result accuracy but also reduces computational costs. Additionally, comparing unstructured and hybrid meshes indicates that using hybrid meshes on a Modified DEM significantly improves accuracy and computational efficiency for flood inundation mapping. A case study of Hurricane Harvey in Houston, Texas, shows a 40 % improvement in flood estimate accuracy and a 34 % reduction in computation time with hybrid meshes on a modified DEM. Additionally, the study evaluates the impact of atmospheric forces and surge, revealing a 20 % improvement in results in the Bay area when atmospheric forces are included. This research underscores the importance of employing accurate DEMs, appropriate meshes tailored to domain features and proper boundary forces for precise flood simulations, helping decision-makers and city planners better assess community vulnerability.