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

consider the effects of climate change. This adjustment helps account for the potential changes in precipitation patterns and intensities expected in the future due to climate change. By incorporating the CCF into the IDF curves, the study aimed to provide estimates of future rainfall intensities that account for the anticipated climate change effects. These esti- mates are essential for designing resilient infrastructure and making informed flood man- agement and water resource planning decisions. The IDF curve develops for return periods of 5, 10, 20, 50, 100, 500, and 1000, 5000, 10,000, 20,000, 50,000, and 100,000 years at Annual Maximum Series (AMS) moving totals for various durations of 1, 2, 3, 4, and 5 hours. AMS moving totals help capture the extreme precipitation events over consecutive hours within a year. Future IDF Curve obtained by derived Climate Change Factor (CCF). The following Eq (9) describes the general relationship between IDF future projections: IF ¼ l0Tk ðd þ yÞZ ð9Þ Where, rainfall intensity for the future. The original was modified, incorporating CCF. Then, the future can be written as: Where, IF Rainfall intensity for future. The original λ was modi- fied as λ^’, which incorporates CCF. Then, the future λ^’ can be written as: l0 ¼ CCFT ð10Þ Thus, the future design rainfall: IF ¼ CCFT ∗ lTk ðd þ yÞZ ð11Þ Then, the annual maximum of 1-hr rainfall events from climate models was used to calcu- late the CCF and subsequently applied to the current curve to develop the future IDF curves. Hydrological model

In this study, the US Army Corps of Engineers Hydrologic Engineering Centre (USACE) used their Hydrologic Modelling System (HEC-HMS) software to simulate flow in branched water- shed systems and determine the inflows across a wide range of return periods (1 to 100,000 years) and simulating the maximum possible flood (PMF) scenarios under various climate change conditions for Batu Dam. 1. Dividing Drainage Area into Subareas: The 50 km2 Batu Dam catchment is divided into six sub-catchments (S1-S6) as in Fig 4 Subareas basin model setup based on different soil types and land use patterns at Batu Dam. This is achieved using GIS tools within HEC-HMS, with a Digital Elevation Model (DEM) from ALOS PALSAR (30 m resolution) in the Universal Transverse Mercator (UTM) coordinate system. 2. Determination of Catchment’s Physical Characteristics: The physical characteristics, such as area, stream length, and slope, are determined using Global Mapper or GIS tools. These characteristics include the longest path of the stream, the centroid length (Lc), and elevation profiles. Data from the Revised Inflow Design Flood Batu Dam Kuala Lumpur Flood Mitigation Project Study (USBR, 1984) is also utilized. Detailed information on the physical characteristics is shown in Table 2. 3. Input parameters for HEC-HMS: All physical characteristics of the Batu Dam sub catch- ments such as the area of sub-catchments, the longest flow path, elevation, and slope of the PLOS ONE Climate change PLOS ONE | https://doi.org/10.1371/journal.pone.0311181 February 27, 2025 9 / 32