Abstract
Hydraulic modeling is a fundamental tool for managing and mitigating flood risk. Developing low resolution hydraulic models, providing consistent inundation simulations with shorter running time, as compared to high-resolution modeling, has a variety of potential applications. Rapid coarse resolution flood models can support emergency management operations as well as the coupling of hydrodynamic modeling with climate, landscape and environmental models running at the continental scale. This work sought to investigate the uncertainties of input parameters and bidimensional (2D) flood wave routing simulation results when simplifying the terrain mesh size. A procedure for fluvial channel bathymetry interpolation and floodplain terrain data resampling was investigated for developing upscaled 2D inundation models. The proposed terrain processing methodology was tested on the Tiber River basin evaluating coarse (150 m) to very coarse (up to 700 m) flood hazard modeling results. The use of synthetic rectangular cross sections, replacing surveyed fluvial channel sections, was also tested with the goal of evaluating the potential use of geomorphic laws providing channel depth, top width and flow area when surveyed data are not available. Findings from this research demonstrate that fluvial bathymetry simplification and DTM resampling is feasible when the terrain data resampling and fluvial cross section interpolation are constrained to provide consistent representation of floodplain morphology, river thalweg profile and channel flow area. Results show the performances of low-resolution inundation simulations running in seconds while maintaining a consistent representation of inundation extents and depths.
Highlights
Floodplain landscape morphology and roughness represent the governing factors of flood flow propagation dynamics [1,2,3,4]
We argue that the downscaling of the flood model resolution—i.e., decreasing the size of the mesh elements that characterize the Digital Terrain Model (DTM) of the inundation domain—has to be properly developed considering the scale and properties of the flood event of interest
Hydrology 2018, The5, procedure is applied and results are presented to depict the effect of the 8 of 16 proposed floodplain terrain processing on flood modeling results with varying performances when upscaling the model from coarse to very coarse resolutions
Summary
Floodplain landscape morphology and roughness represent the governing factors of flood flow propagation dynamics [1,2,3,4]. Recent technological advancements, such as geomatics and remote sensing (or Earth Observation (EO)) sectors, allow for more efficient data gathering of fluvial bathymetry, floodplain topography and surface roughness. Global flood hazard modeling is possible [6] with hyper-resolution hydraulic modeling that are being implemented [7] taking advantage of remotely sensed data from large (i.e., satellite and aerial sensors) to small scale (i.e., drones) fluvial feature and process observation systems [8,9]. The quest for always more accurate and detailed flood models prompts the need for investigations identifying an optimal balance between hydraulic model output details and topographic input data resolution [8]
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