Assessment of Climate Change Impact on Probable Maximum Floods in a Tropical Catchment

Abstract

Increased extreme rainfall due to climate change will increase the probable maximum flood (PMF) and pose a severe threat the critical hydraulic infrastructure like hydroelectric and flood protection dams. As the rainfall extremes in tropical regions are highly sensitive to global warming, increase PMF can be much higher in the tropics. A study has been conducted to assess the impact of climate change on PMF in a tropical catchment located in peninsular Malaysia. A lumped hydrological model, Mike NAM, is calibrated and validated with observed climate and inflow data of Tenmengor reservoir, located in the state of Perak of Peninsular Malaysia. Regional climate model projected rainfall is used to generate probable maximum precipitation (PMP) for future periods. The hydrological model is used to simulate PMF from PMP estimated for the historical and two future periods, early (2031−2045) and late (2060−2075). The results revealed the NAM model could simulate the river flow with a Nash–Sutcliffe efficiency of 0.74 and root mean square error of 0.51. The application of the model with projected rainfall revealed an increase in PMP by 162 to 507% and 259 to 487% during early and late periods for different return periods ranging from 5 to 1000 years. This would cause an increase in PMF by 48.9% and 122.6% during early and late periods. A large increase in PMF indicates the possibility of devastating floods in the study area due to climate change.