Quantifying Uncertainty in Flood Predictions in Fixed Cartesian Flood Model Due To Arbitrary Conventions in Grid Alignment

Abstract Digital elevation models generated by sampling and interpolating LiDAR data onto a square grid can produce reliable flood predictions. However, the arbitrary conventions in grid alignment that can introduce uncertainty in flood predictions are frequently overlooked. Hence, our research quan...

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Main Authors: M. Nguyen, M. D. Wilson, E. M. Lane, J. Brasington, R. A. Pearson
Format: Article
Language:English
Published: Wiley 2025-05-01
Series:Water Resources Research
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Online Access:https://doi.org/10.1029/2024WR038919
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author M. Nguyen
M. D. Wilson
E. M. Lane
J. Brasington
R. A. Pearson
author_facet M. Nguyen
M. D. Wilson
E. M. Lane
J. Brasington
R. A. Pearson
author_sort M. Nguyen
collection DOAJ
description Abstract Digital elevation models generated by sampling and interpolating LiDAR data onto a square grid can produce reliable flood predictions. However, the arbitrary conventions in grid alignment that can introduce uncertainty in flood predictions are frequently overlooked. Hence, our research quantified this uncertainty using a Monte Carlo approach and flood model LISFLOOD‐FP to generate multiple flood simulations for analysis. The simulations were generated by transforming the alignments of the square grid (North translation, East translation, North‐East translation, rotation, and a combination of rotation and translation) with different resolutions (2‐, 5‐, 10‐, and 20‐m). We also used different flood scenarios (5‐, 10‐, 20‐, 50‐, 80‐, and 1,000‐year return periods) to observe how the uncertainty changes in a specific event. Results demonstrate that the grid alignment introduces uncertainty in flood predictions, leading to significant variability in flood extent (7%) and the number of flooded buildings (27%). Because the main river aligns with the grid lines, higher variability in water depths, flood extent, and flooded buildings is associated with grid rotation than translation. Finer resolutions have less variability in water depths, flooded areas, and the number of flooded buildings owing to the decreased movement of LiDAR points between pixels. For each flood scenario, if water overtops certain thresholds in only a few simulations, variations in water depths and flooded areas increase. However, if it only fills locations that can be flooded by water volume in smaller flood event, they decrease. The number of flooded buildings depends on if the inundated regions are residential.
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spelling doaj-art-e5951933593b44f1a3d19aac04bbecb52025-08-20T02:09:31ZengWileyWater Resources Research0043-13971944-79732025-05-01615n/an/a10.1029/2024WR038919Quantifying Uncertainty in Flood Predictions in Fixed Cartesian Flood Model Due To Arbitrary Conventions in Grid AlignmentM. Nguyen0M. D. Wilson1E. M. Lane2J. Brasington3R. A. Pearson4Geospatial Research Institute University of Canterbury Christchurch New ZealandGeospatial Research Institute University of Canterbury Christchurch New ZealandNational Institute of Water and Atmospheric Research (NIWA) Christchurch New ZealandWaterways Centre University of Canterbury Christchurch New ZealandNational Institute of Water and Atmospheric Research (NIWA) Christchurch New ZealandAbstract Digital elevation models generated by sampling and interpolating LiDAR data onto a square grid can produce reliable flood predictions. However, the arbitrary conventions in grid alignment that can introduce uncertainty in flood predictions are frequently overlooked. Hence, our research quantified this uncertainty using a Monte Carlo approach and flood model LISFLOOD‐FP to generate multiple flood simulations for analysis. The simulations were generated by transforming the alignments of the square grid (North translation, East translation, North‐East translation, rotation, and a combination of rotation and translation) with different resolutions (2‐, 5‐, 10‐, and 20‐m). We also used different flood scenarios (5‐, 10‐, 20‐, 50‐, 80‐, and 1,000‐year return periods) to observe how the uncertainty changes in a specific event. Results demonstrate that the grid alignment introduces uncertainty in flood predictions, leading to significant variability in flood extent (7%) and the number of flooded buildings (27%). Because the main river aligns with the grid lines, higher variability in water depths, flood extent, and flooded buildings is associated with grid rotation than translation. Finer resolutions have less variability in water depths, flooded areas, and the number of flooded buildings owing to the decreased movement of LiDAR points between pixels. For each flood scenario, if water overtops certain thresholds in only a few simulations, variations in water depths and flooded areas increase. However, if it only fills locations that can be flooded by water volume in smaller flood event, they decrease. The number of flooded buildings depends on if the inundated regions are residential.https://doi.org/10.1029/2024WR038919uncertainty quantificationgrid alignmentLISFLOOD‐FPMonte Carlo simulationsDEMs
spellingShingle M. Nguyen
M. D. Wilson
E. M. Lane
J. Brasington
R. A. Pearson
Quantifying Uncertainty in Flood Predictions in Fixed Cartesian Flood Model Due To Arbitrary Conventions in Grid Alignment
Water Resources Research
uncertainty quantification
grid alignment
LISFLOOD‐FP
Monte Carlo simulations
DEMs
title Quantifying Uncertainty in Flood Predictions in Fixed Cartesian Flood Model Due To Arbitrary Conventions in Grid Alignment
title_full Quantifying Uncertainty in Flood Predictions in Fixed Cartesian Flood Model Due To Arbitrary Conventions in Grid Alignment
title_fullStr Quantifying Uncertainty in Flood Predictions in Fixed Cartesian Flood Model Due To Arbitrary Conventions in Grid Alignment
title_full_unstemmed Quantifying Uncertainty in Flood Predictions in Fixed Cartesian Flood Model Due To Arbitrary Conventions in Grid Alignment
title_short Quantifying Uncertainty in Flood Predictions in Fixed Cartesian Flood Model Due To Arbitrary Conventions in Grid Alignment
title_sort quantifying uncertainty in flood predictions in fixed cartesian flood model due to arbitrary conventions in grid alignment
topic uncertainty quantification
grid alignment
LISFLOOD‐FP
Monte Carlo simulations
DEMs
url https://doi.org/10.1029/2024WR038919
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