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

resources and dams across various regions, necessitating comprehensive assessments using hydrological models. This study integrated regional climate models with hydrological simulations to predict future scenarios and assess their impacts on Batu Dam, a high-hazard dam located in Selangor. The objective of this study is to assess the overtopping risk of embankment dams caused by hydrological load under the impact of climate change in the twenty-first century. The analysis has been described under a hydrological scenario, where flooding is the main load on which dams are imposed. The climate change projection data was obtained by downscaling Global Climate Models (GCM) to regional data under Coupled Model Intercomparison Project 5 (CMIP5) by NAHRIM spanning the years 2020 to 2100. The projected changes in future rain- fall pattern associated with climate change, and the reliability of existing IDF curves generated from historical data and simplified assumptions, need to be reviewed. Adjustments to the cur- rent IDF curves are necessary for reliable projections of future rainfall under different climate change scenarios. This study used generated GCM rainfall data simulations for four stations in the catchment area, considering RCP4.5, RCP6.0, and RCP8.5 scenarios. Then, an analysis of PMP is conducted by the NAHRIM envelope curve [22], which will then be an input to esti- mate the PMF. The result of simulated inflow design flood and check with the dam designed inflow to predict the probability of overtopping.

The overtopping risk of high-hazard embankment dams is a critical concern, especially under the changing climate conditions in Malaysia. As global temperatures rise and weather patterns become more unpredictable, the potential for extreme rainfall events leading to dam overtopping risk increases. Understanding and mitigating this risk is essential for ensuring the safety and stability of these vital structures. Dam safety management must consider climate change impacts [35]. Addressing this risk is imperative to safeguard communities and infra- structure downstream of these dams. Besides, to further carry out the adaptation of climate change under Sustainable Development Goals (SDG) 13 toward climate action for global sustainability. Study area The Batu Dam is considered the most critical dam due to its high hazard rating due to its high- est crest elevation, water level, and shortest distance to the downstream populous region [17]. The downstream region of the dam is densely populated and has been constructed to safeguard almost 1.25 million people affected by the threat of flooding. It encompasses a range of indus- tries, treatment plants for water, and residential areas. Due to a major flood in Kuala Lumpur in 1971, the establishment of this dam was mandated as part of a larger project to minimise the occurrence of future flooding mainly, protect against flooding in the Kuala Lumpur metropoli- tan area, and it also serves as a water supply reservoir. A surcharge, collectively with a spillway

and outlet, is established to allow for a discharge of 287.4 m3/s. This is done to defend from the inflow design flood. Fig 1 shows the study area of Batu Dam. Data This study obtained historical hydrological data from Malaysia Department of Irrigation and Drainage (DID) for four rainfall stations near the Batu Dam basin as illustrated in Fig 2. These stations include (i) 3216001—Kampung Sungai Tua (Kg. Sg. Tua), (ii) 3217001— Ibu Bekalan KM16, (iii) 3317001—Air Terjun, and (iv) 3317004 –Genting Sempah as show in Fig 2. The dataset’s gaps were filled using the Close Neighbour approach. Climate change’s impact on future water resources has been projected using GCM simulation data. Regional Climate Models (RCMs) are regional climate projections and climatic PLOS ONE Climate change PLOS ONE | https://doi.org/10.1371/journal.pone.0311181 February 27, 2025 4 / 32