Constructing short‐duration IDF curves using coupled dynamical–statistical approach to assess climate change impacts

Abstract

This study demonstrates a methodology to construct short‐duration rainfall intensity–duration–frequency (IDF) curves and to quantify the variability in the rainfall intensities for different return periods with respect to the changing climate. A dynamical downscaling approach using the regional climate model (RCM) Weather Research and Forecasting (WRF) has been used to assess present and future climates using the downscaling of an ensemble of three global climate models (GCMs) (CSIRO‐ACCESS1.3, MPI‐ESM‐MR ECHAM6 and NIES‐MIROC5) under the Coupled Model Intercomparison Project phase 5 (CMIP5). Furthermore, a statistical approach using the well‐known simple scaling method has been applied to extend the 6‐hourly WRF precipitation output to the finer temporal scale of 10 min. The short‐duration IDF curves were then constructed for the present and future climates under two representative concentration pathway (RCP) scenarios RCP4.5 and RCP8.5. A preliminary examination for this case study over Bac Ninh, an industrial area in the northern Vietnam, shows that there is a substantial increase in short‐duration rainfall intensity in the future with respect to the baseline climate. The highest increase is towards the end of the century (2071–2100) ranging from 56 to 61% for a 10‐ and 100‐year return period for 24‐hr duration, respectively, while the increase is about 40–45% for the 10‐min duration. These results strongly suggest that severe flooding in the future climate over the study region may be likely. The study results might be useful for policymakers and infrastructure planning and for insurance companies around the study area.