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Volume 15, Issue 3 (Autumn 2025)
Disaster Prev. Manag. Know. 2025, 15(3): 384-413 |
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Vayskarami I, Haghizadeh A, Fathabadi A. Impact of Digital Elevation Model Resolution on Flood Hazard Simulation: A Case Study of the River Downstream of Khorramabad City, Iran. Disaster Prev. Manag. Know. 2025; 15 (3) :384-413
URL: http://dpmk.ir/article-1-741-en.html
URL: http://dpmk.ir/article-1-741-en.html
1- Department of Watershed Management Engineering, Faculty of Natural Resources, Lorestan University, Khorramabad, Iran.
2- Department of Watershed Management Engineering, Faculty of Agriculture and Natural Resources, Gonbad Kavous University, Gonbad Kavous, Iran.
2- Department of Watershed Management Engineering, Faculty of Agriculture and Natural Resources, Gonbad Kavous University, Gonbad Kavous, Iran.
Abstract: (456 Views)
Background and Objective Despite significant advancements in the development of hydraulic models, the accuracy of flood predictions is influenced by various factors, including topography, the precision of digital elevation models (DEMs), and roughness coefficients. This study aimed to evaluate the effect of DEM resolution on the efficiency of the 2D HEC-RAS model in simulating flood hazard zones.
Method Three DEM layers with resolutions of 0.5, 2, and 3 meters were used to assess the efficiency of the 2D HEC-RAS model. Water flow simulations were conducted in a 3-kilometer-long section of the river downstream of Khorramabad City, Lorestan Province, Iran. Measured flow rates in April and November 2024 (34 and 15 m3/s, respectively) and the flow rate during a flood event in April 2019 (1000 m3/s) were considered. The flow variables (including depth, velocity, and spread width) measured based on the DEM layers were compared with the values measured at four cross-sections within the study area for the specified flow rates. The evaluation metrics were the root mean square error (R.M.S.E) and mean absolute percentage error (M.A.P.E).
Results Using the DEM with a resolution of 0.5 meters yielded simulation results for flow and flood hazard maps that were much closer to the real data compared to those obtained from DEMs with lower resolutions of 2 and 5 meters. The average prediction errors for flow depth and velocity using the 0.5-m resolution DEM were 10% and 12% lower, respectively, than those of the 2-m and 5-m resolution DEMs. Additionally, analyses of hydraulic parameters, including flow depth, velocity, and spread width, revealed a significant correlation between DEM resolution and flood prediction accuracy.
Conclusion The resolution of DEMs plays a crucial role in enhancing the performance of the 2D HEC-RAS model in simulating flood hazard zones. With higher DEM resolution, better flood prediction results can be obtained. Therefore, it should be considered as an effective strategy in flood risk management and reducing flood-related damages. The findings underscore the importance of hydraulic model precision and the necessity of utilizing high-resolution models in studies related to flood risk management and mitigation.
Method Three DEM layers with resolutions of 0.5, 2, and 3 meters were used to assess the efficiency of the 2D HEC-RAS model. Water flow simulations were conducted in a 3-kilometer-long section of the river downstream of Khorramabad City, Lorestan Province, Iran. Measured flow rates in April and November 2024 (34 and 15 m3/s, respectively) and the flow rate during a flood event in April 2019 (1000 m3/s) were considered. The flow variables (including depth, velocity, and spread width) measured based on the DEM layers were compared with the values measured at four cross-sections within the study area for the specified flow rates. The evaluation metrics were the root mean square error (R.M.S.E) and mean absolute percentage error (M.A.P.E).
Results Using the DEM with a resolution of 0.5 meters yielded simulation results for flow and flood hazard maps that were much closer to the real data compared to those obtained from DEMs with lower resolutions of 2 and 5 meters. The average prediction errors for flow depth and velocity using the 0.5-m resolution DEM were 10% and 12% lower, respectively, than those of the 2-m and 5-m resolution DEMs. Additionally, analyses of hydraulic parameters, including flow depth, velocity, and spread width, revealed a significant correlation between DEM resolution and flood prediction accuracy.
Conclusion The resolution of DEMs plays a crucial role in enhancing the performance of the 2D HEC-RAS model in simulating flood hazard zones. With higher DEM resolution, better flood prediction results can be obtained. Therefore, it should be considered as an effective strategy in flood risk management and reducing flood-related damages. The findings underscore the importance of hydraulic model precision and the necessity of utilizing high-resolution models in studies related to flood risk management and mitigation.
Type of Study: Case report |
Subject:
Special
Received: 2025/01/10 | Accepted: 2025/05/31 | ePublished: 2025/10/1
Received: 2025/01/10 | Accepted: 2025/05/31 | ePublished: 2025/10/1
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