EGU25-17954, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-17954
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Two-Dimensional Hydrodynamic Modeling and Comparison of Flood Propagation from İmranlı Dam Break Using Different Remotely Sensed Topographic Data
Gokcen Uysal and Enver Tasci
Gokcen Uysal and Enver Tasci
  • Eskisehir Technical University, Faculty of Engineering, Department of Civil Engineering, Eskisehir, Türkiye (gokcenuysal@eskisehir.edu.tr)

Floods exacerbated by climate change significantly increase the risk of dam failure, posing a critical threat to downstream regions. A cost-effective way to analyze the consequences of dam break floods is by using unsteady hydrodynamic models that incorporate St. Venant’s or diffusion wave equations. These models require detailed topographic data, land cover information, and a dam break hydrograph. This study assesses the influence of various remote sensing topographic datasets on 2-dimensional (2D) hydrodynamic flood modeling using HEC-RAS v6. The methodology is applied to İmranlı town in Türkiye, located downstream of an irrigation dam. Under a 500-year return period flood scenario, a breach hydrograph is simulated in HEC-RAS, assuming overtopping when the reservoir is at full capacity. Manning's roughness values are derived from the ESA-WorldCover satellite land use map. Two types of topographic data are tested: Digital Surface Models (DSMs) and Digital Terrain Models (DTMs). Specifically, datasets include field-based Light Detection and Ranging (LiDAR) DSM (0.5 x 0.5 m resolution), Turkish General Directorate of Mapping (HGM)-based DSM (5 x 5 m resolution), Advanced Land Observing Satellite – Phased Array type L-band Synthetic Aperture Radar (ALOS-PALSAR)-sourced DTM (12.5 x 12.5 m resolution), and Shuttle Radar Topography Mission (SRTM)-sourced DTM (30 x 30 m resolution).

The study also explores the impact of combining high-resolution and low-resolution topographic data by mosaicking LiDAR data, limited to urbanized areas, with other datasets. Results are evaluated using performance metrics such as Mean Absolute Error (MAE), Root Mean Square Error (RMSE), F-index, and correlation coefficient (R²). Additionally, comparisons are drawn using flood-related maps, including flood inundation area, water depth, velocity, duration, and hazard. The study highlights that nearly the entire İmranlı district center and the Doğançal settlement would be inundated in the event of a dam failure, exposing approximately 7,028 individuals to flood risk. The findings suggest that while high-resolution HGM-based data serve as a reliable reference, integrating satellite datasets like ALOS-PALSAR with LiDAR enhances model performance, making them valuable alternatives when high-resolution data are unavailable.

How to cite: Uysal, G. and Tasci, E.: Two-Dimensional Hydrodynamic Modeling and Comparison of Flood Propagation from İmranlı Dam Break Using Different Remotely Sensed Topographic Data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17954, https://doi.org/10.5194/egusphere-egu25-17954, 2025.