Statistical downscaling of CMIP5 outputs for projecting future changes in rainfall in the Onkaparinga catchment

Rashid, Md. Mamunur and Beecham, Simon and Chowdhury, Rezaul K. (2015) Statistical downscaling of CMIP5 outputs for projecting future changes in rainfall in the Onkaparinga catchment. Science of the Total Environment, 530-531. pp. 171-182. ISSN 0048-9697

Abstract

A generalized linear model was fitted to stochastically downscaled multi-site daily rainfall projections from
CMIP5 General Circulation Models (GCMs) for the Onkaparinga catchment in South Australia to assess future
changes to hydrologically relevant metrics. For this purpose three GCMs, two multi-model ensembles (one by averaging the predictors of GCMs and the other by regressing the predictors of GCMs against reanalysis datasets) and two scenarios (RCP4.5 and RCP8.5) were considered. The downscaling model was able to reasonably reproduce the observed historical rainfall statistics when the model was driven by NCEP reanalysis datasets. Significant bias was observed in the rainfall when downscaled from historical outputs of GCMs. Bias was corrected using the Frequency Adapted Quantile Mapping technique. Future changes in rainfall were computed from the bias corrected downscaled rainfall forced by GCM outputs for the period 2041–2060 and these were then compared to the base period 1961–2000. The results show that annual and seasonal rainfalls are likely to significantly decrease for all models and scenarios in the future. The number of dry days and maximum consecutive dry days will increase whereas the number of wet days and maximum consecutive wet days will decrease. Future changes
of daily rainfall occurrence sequences combined with a reduction in rainfall amounts will lead to a drier catchment, thereby reducing the runoff potential. Because this is a catchment that is a significant source of Adelaide's water supply, irrigation water and water for maintaining environmental flows, an effective climate change adaptation strategy is needed in order to face future potential water shortages.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version, in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying
Date Deposited: 04 Jun 2018 05:18
Last Modified: 03 Sep 2018 03:50
Uncontrolled Keywords: generalized linear model, general circulation model, downscaling, rainfall, bias correction, climate change
Fields of Research : 04 Earth Sciences > 0401 Atmospheric Sciences > 040105 Climatology (excl.Climate Change Processes)
09 Engineering > 0905 Civil Engineering > 090509 Water Resources Engineering
Socio-Economic Objective: D Environment > 96 Environment > 9603 Climate and Climate Change > 960304 Climate Variability (excl. Social Impacts)
Identification Number or DOI: doi: 10.1016/j.scitotenv.2015.05.024
URI: http://eprints.usq.edu.au/id/eprint/34223

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