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

Intensity duration frequency curve Historical rainfall intensity duration frequency (IDF) curve. Eq 8 was used to correct the IDF relationship for historical rainfall (Fig 10). The parameters λ, k, θ, and η were derived and generalised for the construction of IDF from simulated rainfall. The future IDF projection was obtained through distribution analysis to compute the return period for different dura- tions. The outputs were used to produce a future IDF table consisting of rainfall intensity, duration, and return period. Eq 8 demonstrates the typical IDF relationship for a specific return period obtained from the Department of Irrigation and Drainage Malaysia to calculate the IDF parameters. The calculated parameters are tabulated in Table 4. Future IDF curve for Batu Dam catchment. The corrected projected areal rainfall data from the Batu Dam catchment for a 1-hour period were used to generate IDF curves. These curves were generated for a range of time periods, including 5, 10, 20, 50, 100, 500, and 1000 years, as well as 5000, 10,000, 20,000, 50,000, and 100,000 years. Table 5 provides the values of CCF for deriving future IDF curves for different return periods, as shown in Figs 11–13. Inflow design flood hydrograph and PMF. PMF and IDF for (1, 3, 6, and 12 hours) and 24 hours (1,3 and 5-day) as shown in Fig 14 indicated the extreme flood peak at Batu Dam occurred after three hours with an inflow for the whole century and in different RCP 4.5, 6.0 and 8.5. Fig 15 illustrates the extreme flood peak at Batu Dam occurred after three hours with

an inflow for the whole century and in different RCP 4.5, 6.0, and 8.5 scenarios. Historical data hydrograph. The following hydrograph presents historical peak inflow data for Batu Dam under design flood conditions. Fig 7. Corrected daily projected rainfall (RCP 8.5) time series for Kg. Sg. Tua rainfall station. a) Corrected daily rainfall at Early Century b) Corrected daily rainfall at Mid Century c) Corrected daily rainfall at Late Century. https://doi.org/10.1371/journal.pone.0311181.g007 Fig 8. Average annual historical dan projected future rainfall for the Batu Dam catchment under all RCPs. Historical Data (1975–2020): Solid blue line shows recorded rainfall, fluctuating significantly with a spike around 1998–1999). RCP4.5 Projected Data (2020–2099): Dashed yellow line represents considerable variation in future rainfall projections. RCP6.0 Projected Data (2020–2099): Dashed orange line, showing increased variability and more extreme rainfall events. RCP8.5 Projected Data (2020–2099): Dashed red line predicting greater variability and extreme rainfall projections. https://doi.org/10.1371/journal.pone.0311181.g008 PLOS ONE Climate change PLOS ONE | https://doi.org/10.1371/journal.pone.0311181 February 27, 2025 15 / 32