Overtopping risk of high-hazard embankment dam under climate change condition

RESEARCH ARTICLE Overtopping risk of high-hazard embankment dam under climate change condition Wan Noorul Hafilah Wan Ariffin1*, Lariyah Mohd Sidek1*, Hidayah Basri1, Noorhayati Idros1, M. Torres Adrian2, Noor Hisham Abd Ghani3, Hazri Mohd Khambali4, Siti Mariam Allias Omar1, Muhammad Izzat Azhar Khebir1, Ali Najah AhmedID5 1 Dam Safety and Sustainability Intelligence Group, Institute of Energy Infrastructure, Universiti Tenaga Nasional (UNITEN), Selangor, Malaysia, 2 INGENIERI´A DE PRESAS S.L., Valencia, Spain, 3 National Water Research Institute of Malaysia (NAHRIM), Ministry of Energy Transition and Water Transformation (PETRA), Selangor, Malaysia, 4 Design and Dam Division, Department of Irrigation & Drainage, Kuala Lumpur, Malaysia, 5 Department of Engineering School of Engineering and Technology, Sunway University, Bandar Sunway, Petaling Jaya, Malaysia * noorul@water.gov.my (WNHWA); lariyah@uniten.edu.my (LMS) Abstract Climate change poses an escalating threat to the safety of high-hazard embankment dams, increases flood discharge impacting dam overtopping risk by altering the hydrological load of the original dam designed capacity. This paper’s primary aims are to evaluate climate change’s influence on extreme rainfall events and their impact on dam safety and to assess the overtopping risk of Batu Dam under various climate scenarios. This study focusses on assessing the overtopping risk of Batu Dam in Malaysia, utilizing regional climate model pro- jections from the Coupled Model Intercomparison Project 5 (CMIP5) spanning 2020 to

2100. Three Representative Concentration Pathways (RCPs)—RCP4.5, RCP6.0, and RCP8.5 as the scenario and divide into 3 period of study: early century (2020–2046), mid (2047–2073) and late-century (2074–2100) evaluated with hydrological analysis to access the dam safety. Using the Linear Scaling Method (LSM), we corrected the bias projection rainfall data from three Regional Climate Models (RCMs) for the RCPs. Future Probable Maximum Precipitation (PMP) was estimated using statistical analysis techniques devel- oped by the National Hydraulic Research Institute of Malaysia (NAHRIM). Additionally, Rainfall Intensity-Duration-Frequency (IDF) curves were updated based on climate scenar- ios outlined in the Hydrological Procedure 2021 and the associated Climate Change Fac- tors. The HEC-HMS hydrological model was employed to simulate PMF and IDF for ARIs ranging from 1 to 100,000 years, providing a comprehensive analysis of risks under future climatic conditions. Across all future climate scenarios, inflow events were projected to exceed the dam design inflow, with RCP8.5 indicating the highest inflow values, particularly later in the century, highlighting probability of overtopping risks. Late-century projections show inflow for ARI 50 under RCP8.5 exceeding PMF by 20%, while mid-century RCP6.0 results indicate a 15% higher inflow for ARI 50000. Early-century RCP4.5 shows a 10% increase for ARI 100000 compared to PMF. The study advocates adaptive dam safety man- agement and flood protection measures. This research provides crucial insights for embank-

ment dam owners, stressing the urgent need to address Batu Dam’s vulnerability to PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0311181 February 27, 2025 1 / 32 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Hafilah Wan Ariffin WN, Sidek LM, Basri H, Idros N, Adrian MT, Abd Ghani NH, et al. (2025) Overtopping risk of high-hazard embankment dam under climate change condition. PLoS ONE 20(2): e0311181. https://doi.org/10.1371/journal. pone.0311181 Editor: Sher Muhammad, ICIMOD: International Centre for Integrated Mountain Development, NEPAL Received: June 7, 2024 Accepted: September 14, 2024 Published: February 27, 2025 Copyright: © 2025 Hafilah Wan Ariffin et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: Rainfall data used in this study provided in the supplementary. Funding: This study was supported by Asia-Pacific Network (APN) via Collaborative Regional Research Programme (Project Code: CRRP2022- 07MY-Basri) and the Ministry of Higher Education (MoHE), Malaysia, through the Trans Disciplinary Research Grant Scheme, under project code of TRGS/1/2020/UNITEN/01/1/1.