Changes in future rainfall extremes over northwest Bangladesh using multi-model ensemble

Abstract

Bangladesh is rich in nearly every form of natural resource. Underground water and rainfall are critical parameters in civil and mechanical engineering. The impacts of climate change on precipitation across Bangladesh's northwestern zone were explored using daily precipitation data from eight bias-corrected general circulation models (GCMs) under the representative concentration pathway (RCP) 4.5 and RCP 8.5 scenarios. The northwestern zone is particularly prone to drought. CMIP5 models perform a probabilistic forecast of the future using the precipitation indices for the time period of (2010-2099). We will forecast changes in future climate indices for the period 2020-2099 using observed data and GCM model data. Future timespan can be separated into two sections: one is the near future (2020-2059) and another one is the far future (2060-2099). Menn-Kendell Test will give us future trend analysis report. Bayesian Model Averaging (BMA) will be used to do multi-model ensemble. Changes in extreme climate indices will be projected by spatial mapping. Extremely heavy precipitation days & heavy precipitation days are decreasing in almost all stations. But total annual precipitation has an increasing trend. For high emission scenario change in climate indices are more prominent & devastating. These are the major findings of this thesis. Our study only focuses on precipitation. But temperaturerelated indices are skipped in this case due to time shortage. So, giving a perfect future climate scenario is quite tough. It’s a major limitation in our study. But we see that most of the cases the indices are changing insignificantly in Ishwardi station. In some cases, Rangpur & Dinajpur will face some extreme weather events.