Boudaghpour (2025) Hydrological impacts of climate-driven flood risks: analyzing the AqQala historical bridge collapse over the Gorganrud river

Identification

• Journal: Modeling Earth Systems and Environment
• Year: 2025
• Date: 2025-12-15
• Authors: Siamak Boudaghpour
• DOI: 10.1007/s40808-025-02700-9

Research Groups

• K.N.Toosi University of Technology, Tehran, Iran

Short Summary

This study developed a flood risk forecasting model for the AqQala Historical Bridge over the Gorganrud River to analyze hydrological impacts of climate-driven flood risks under various bridge collapse scenarios. It found that while 25-year floods pose minimal risk, 50- and 100-year floods significantly increase inundation risk when structural failure exceeds 70%, highlighting the urgent need for adaptive flood management and resilient infrastructure planning in the face of climate change.

Objective

• To examine the hydrological processes and risks associated with the collapse of the AqQala Historical Bridge over the Gorganrud River during climate-driven extreme weather events.
• To propose a novel environmental risk-forecasting model for historical bridges, integrating current hydrological data with climate change projections to provide a comprehensive framework for understanding evolving flood risks for infrastructure planning and environmental management.

Study Configuration

• Spatial Scale: Approximately 880 meters of the Gorganrud River, specifically focusing on the AqQala Historical Bridge (70 meters in length) and the nearby Bahonar Bridge, located in AqQala, Golestan Province, north of Iran.
• Temporal Scale: Analysis of 25-year, 50-year, and 100-year return period flood events, with model calibration and validation using data from a major flood event that occurred from March 28 to April 10, 2012.

Methodology and Data

• Models used:
  • HEC-RAS software (version 4.1.0) for one-dimensional flood modeling and analysis of river behavior.
  • ArcGIS (version 10.4) for processing geographic information system (GIS) data.
  • ENVI (version 5.3.1) for processing satellite images.
• Data sources:
  • Regional Water Company of Golestan (GSRW) (2012a, b) for Gorganrud River and AqQala Historical Bridge data, including altitude, slope, river width, riverbed soil profile, average temperature, annual precipitation, maximum river discharge values for 25-, 50-, and 100-year flood events, and the hydrograph for the 2012 flood.
  • Satellite images.
  • Field surveys for observed river flow measurements used in model validation.

Main Results

• Under normal bridge conditions, a 25-year flood presents negligible inundation risk, while a 50-year flood approaches the overflow threshold, and a 100-year flood poses a considerably higher inundation risk, potentially exceeding the river's maximum depth of 7.7 meters.
• For scenarios where 20% of the first two bridge spans collapsed, water levels were slightly lower than a 25-year flood in normal conditions, with collapsed sediment acting as an ogee spillway, altering water levels.
• When structural failure exceeded 70% (70% and 100% collapse of the first two spans), the risk of overflow and inundation increased significantly, transforming the bridge into a dam with a limited water outlet, leading to substantial water accumulation upstream.
• In severe collapse scenarios (e.g., 100% collapse), water blockage shifted flow to the right side with approximately 7.7 times higher velocity, exacerbating erosion and contributing to potential complete bridge collapse.
• Climate change is projected to increase the frequency and intensity of extreme weather events, making historical flood data unreliable for future planning and necessitating reassessment of flood management infrastructure.

Contributions

• Developed a novel environmental risk-forecasting model specifically for historical bridges, addressing a gap in existing literature.
• Highlighted the critical interaction between hydrological processes, infrastructure vulnerability, and climate change impacts on historical structures.
• Emphasized the urgent need for adaptive measures in flood management and resilient infrastructure planning, particularly for culturally significant historical bridges.
• Demonstrated that integrating climate change projections into flood risk assessments is essential, as historical data alone are insufficient for future flood preparedness.
• Provided a comprehensive framework for understanding the complex interplay of evolving flood risks, sediment dynamics, and infrastructure stability in the context of climate change.
• Advocated for an interdisciplinary approach to flood risk management, integrating hydrology, engineering, and cultural heritage preservation.

Funding

The author declares that no funds, grants, or other support were received during the preparation of this manuscript.

Citation

@article{Boudaghpour2025Hydrological,
  author = {Boudaghpour, Siamak},
  title = {Hydrological impacts of climate-driven flood risks: analyzing the AqQala historical bridge collapse over the Gorganrud river},
  journal = {Modeling Earth Systems and Environment},
  year = {2025},
  doi = {10.1007/s40808-025-02700-9},
  url = {https://doi.org/10.1007/s40808-025-02700-9}
}