Flood Hazard Assessment and Mitigation in the Tigris River: An HEC-RAS Approach (Al-Kut Dam to Al-Musandawq)

Document Type : Original Article

Authors

Department of Civil Engineering, Faculty of Engineering and Technology, University of Mazandaran, Mazandaran, Iran

Abstract

This study addresses the critical issue of flood hazard management in the Maysan region of Iraq, a city highly susceptible to recurrent and devastating floods, as tragically demonstrated by the 2019 flood event. Focusing on a 169 km reach of the Tigris River downstream of the Al-Kut barrage, including the Al-Musandawq channel, this research investigates the impact of riverine obstacles on flood dynamics. The primary objective is to assess and mitigate flood hazards through advanced hydrological modeling. The study employed the HEC-RAS model, utilizing 169 cross-sections surveyed in 2017 and incorporating digital elevation model (DEM) data. Model calibration, using hydrological and topographical inputs, yielded a Manning’s roughness coefficient of 0.031 for the Tigris River and 0.028 for the Al-Musandawi channel. High accuracy was confirmed by Nash-Sutcliffe Efficiency (NSE) indices of 0.979 and 0.986, respectively, alongside other error metrics (RMSE, MAE). Model simulations revealed that flood waves were primarily delayed, reaching Maysan city with minimal dispersion, leading to inundation. To mitigate these risks, two management approaches were considered: (1) removal of islands and sidebars within the river reach, and (2) construction of a weir. Due to the high cost and limited effectiveness of removing natural obstacles, the focus shifted to structural solutions. Scenarios were developed to design a weir with an optimal crest elevation. The goal was to prevent downstream flow to Maysan city from exceeding 700 m³s during flood seasons, while ensuring a minimum flow of 250 m³s during dry seasons. Simulations of peak flow rates (4000, 2500, 1050, 533, and 250 m³s) established an optimal weir crest elevation of 9.4 meters. This study provides crucial insights into flood mitigation strategies for the Tigris River, offering a data-driven approach to protect vulnerable downstream areas.

Keywords

Main Subjects

References

  1. Aerts, J. C., Botzen, W. W. Climate change impacts on pricing long-term flood insurance: A comprehensive study for the Netherlands. Global environmental change, 2011; 21: 1045–1060. doi:10.1016/j.gloenvcha.2011.04.005.
  2. Mohammed-Ali, W. S., Khairallah, R. S. Flood Risk Analysis: The Case of Tigris River (Tikrit/Iraq). Tikrit Journal of Engineering Sciences, 2023; 30: 112–118. doi:10.25130/tjes.30.1.11.
  3. Sabeeh, N. N., Alabdraba, W. M. S. The Hydrodynamic Model using HEC-RAS: The case of Tigris River Downstream of Samarra Barrage (Iraq). In: InIOP Conference Series: Earth and Environmental Science; 2022; p. 012017.
  4. Pekel, J. F., Cottam, A., Gorelick, N., Belward, A. S. High-resolution mapping of global surface water and its long-term changes. Nature, 2016; 540: 418–422. doi:10.1038/nature20584.
  5. Yarahmadi, M., Eskandari Damaneh, H., Khalighi Sigaroodi, S. Assessment of the Impact of Land Use/Land Cover Changes in the Hamoun Wetland on Land Surface Temperature Using Satellite Imagery. Civil Engineering and Applied Solutions, 2025; 1: 31–42. doi:10.22080/ceas.2025.29153.1009.
  6. Tellman, B., Sullivan, J. A., Kuhn, C., Kettner, A. J., Doyle, C. S., Brakenridge, G. R., Erickson, T. A., Slayback, D. A. Satellite imaging reveals increased proportion of population exposed to floods. Nature, 2021; 596: 80–86. doi:10.1038/s41586-021-03695-w.
  7. Nearing, G., Cohen, D., Dube, V., Gauch, M., Gilon, O., Harrigan, S., Hassidim, A., Klotz, D., Kratzert, F., Metzger, A., Nevo, S. Global prediction of extreme floods in ungauged watersheds. Nature, 2024; 627: 559–563. doi:10.1038/s41586-024-07145-1.
  8. Suresh, S., Hossain, F., Minocha, S., Das, P., Khan, S., Lee, H., Andreadis, K., Oddo, P. Satellite-based tracking of reservoir operations for flood management during the 2018 extreme weather event in Kerala, India. Remote Sensing of Environment, 2024; 307: 114149. doi:10.1016/j.rse.2024.114149.
  9. Aziz, F., Wang, X., Mahmood, M. Q., Awais, M., Trenouth, B. Coastal urban flood risk management: Challenges and opportunities− A systematic review. Journal of Hydrology, 2024; 645: 132271. doi:10.1016/j.jhydrol.2024.132271.
  10. Hansson, K., Danielson, M., Ekenberg, L. A framework for evaluation of flood management strategies. Journal of environmental management, 2008; 86: 465–480. doi:10.1016/j.jenvman.2006.12.037.
  11. Menoni, S., Molinari, D., Ballio, F., Minucci, G., Mejri, O., Atun, F., Berni, N., Pandolfo, C. Flood damage: a model for consistent, complete and multipurpose scenarios. Natural Hazards and Earth System Sciences, 2016; 16: 2783–2797. doi:10.5194/nhess-16-2783-2016.
  12. Hino, M., BenDor, T. K., Branham, J., Kaza, N., Sebastian, A., Sweeney, S. Growing safely or building risk? Journal of the American Planning Association, 2024; 90: 50–62. doi:10.1080/01944363.2022.2141821.
  13. Chakraborty, L., Thistlethwaite, J., Scott, D., Henstra, D., Minano, A., Rus, H. Assessing social vulnerability and identifying spatial hotspots of flood risk to inform socially just flood management policy. Risk Analysis, 2023; 43: 1058–1078. doi:10.1111/risa.13978.
  14. Jemberie, M. A., Melesse, A. M. Urban flood management through urban land use optimization using LID techniques, city of Addis Ababa, Ethiopia. Water, 2021; 13: 1721. doi:10.3390/w13131721.
  15. Long'or Lokidor, P., Taka, M., Lashford, C., Charlesworth, S. Nature‐based solutions for sustainable flood management in East Africa. Journal of Flood Risk Management, 2024; 17: e12954. doi:10.1111/jfr3.12954.
  16. Erena, S. H., Worku, H., De Paola, F. Flood hazard mapping using FLO-2D and local management strategies of Dire Dawa city, Ethiopia. Journal of Hydrology: Regional Studies, 2018; 19: 224–239. doi:10.1016/j.ejrh.2018.09.005.
  17. Nigusse, A. G., Adhanom, O. G. Flood hazard and flood risk vulnerability mapping using geo-spatial and MCDA around Adigrat, Tigray region, Northern Ethiopia. Momona Ethiopian Journal of Science, 2019; 11: 90–107. doi:10.4314/mejs.v11i1.6.
  18. Ban, H. J., Kwon, Y. J., Shin, H., Ryu, H. S., Hong, S. Flood monitoring using satellite-based RGB composite imagery and refractive index retrieval in visible and near-infrared bands. Remote Sensing, 2017; 9: 313. doi:10.3390/rs9040313.
  19. Ruiz-Bellet, J. L., Balasch, J. C., Tuset, J., Barriendos, M., Mazon, J., Pino, D. Historical, hydraulic, hydrological and meteorological reconstruction of Santa Tecla flash floods in Catalonia (NE Iberian Peninsula). Journal of Hydrology, 2015; 524: 279–295. doi:10.1016/j.jhydrol.2015.02.023.
  20. Chaudhry, M. H. Applied hydraulic transients. 3 ed. New York (US): Springer; 2014. doi:10.1007/978-1-4614-8538-4.
  21. Brunner, G. W. HEC-RAS river analysis system 2D modeling user’s manual. US Army Corps of Engineers—Hydrologic Engineering Center. 2016. Report No.:
  22. Babister, M., Barton, C. Australian Rainfall and Runoff Revision Project 15: Two Dimensional Modelling in Urban and Rural Floodplains. Canberra (AUS): Geoscience; 2012. Report No.: P15/S1/009.
  23. Maidment, D. R., Mays, L. W. Applied hydrology, Water Resources Handbook. Applied hydrology, Water Resources Handbook. New York, NY, USA: McGraw-Hill. ed. 1988.
  24. Chow, V. T. Open Channel Hydraulics. Il ed. Mc Graw Hill, New York; 1950.
Civil Engineering and Applied Solutions
Volume 3, Issue 1
Issue in Progress
January 2027
Pages 98-116

Files

History

  • Receive Date: 13 March 2026
  • Revise Date: 31 March 2026
  • Accept Date: 01 June 2026
  • First Publish Date: 01 June 2026

Share

How to cite

Statistics