Assessing the impact of climate change on flood characteristics at Langat river basin using Rainfall-Runoff Inundation (RRI) model

Abstract

Flood modelling is one of popular tools in flood management. It can simulate flood depth and streamflow at different sections of the studied area enabling hydrologist to have better understanding on the flood especially with the impact of climate change. This study aims to understand the flood impact due to climate change in a basin scale using Rainfall-Runoff Inundation (RRI) model. Langat River Basin in Selangor, Malaysia is selected due to its location and urbanised area. The RRI were set up and calibrated based on observed data obtained from Department of Irrigation and Drainage (DID) Malaysia, topographic data from HydroSHEDS at 15 arc-second and landuse data from PLANMalaysia. The projected climate data (2080–2099) were extracted from Non-Hydrostatic Regional Climate Model (NHRCM) developed by Meteorological Research Institute (MRI) under the worst case scenario, RCP8.5. The maximum 1-day rainfall at 100-year ARI were chosen as the rainfall input in RRI. It is found that the rainfall intensities in projected 100-year ARI shows a decrement by 6.4% to 12.4% at most area in Langat River Basin. This has cause the peak streamflow in Langat River to reduce by 6.8% and peak flood depth to change by ±3% in the future. Thus, it can be inferred that due to climate change, the peak streamflow and flood depth at Langat River Basin is reduce in the future though the impact is low.