STANDARDIZED PRECIPITATION INDEX (SPI) AND STANDARDIZED PRECIPITATION EVAPOTRANSPIRATION INDEX (SPEI) DROUGHT CHARACTERISTIC AND TREND ANALYSIS USING THE SECOND GENERATION CANADIAN EARTH SYSTEM MODEL (CanESM2) OUTPUTS UNDER REPRESENTATIVE CONCENTRATION PATHWAY (RCP) 8.5, Carpathian Journal of Earth and Environmental Sciences, August 2019, Vol. 14, No. 2, p. 399 - 408; DOI:10.26471/cjees/2019/014/089 - Carpathian Journal of Earth And Environmental Sciences

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Kit Fai FUNG¹, Yuk Feng HUANG^1*, Chai Hoon KOO¹ & Kok Weng TAN²

¹Department of Civil Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Bandar Sungai Long, Cheras, 43000 Kajang, Selangor, Malaysia: kitfaifung@gmail.com; *huangyf@utar.edu.my; kooch@utar.edu.my

²Department of Environmental Engineering, Faculty of Engineering and Green Technology, Universiti Tunku Abdul Rahman, Jalan Universiti, Bandar Barat, 31900 Kampar, Perak, Malaysia: tankokweng@utar.edu.my

STANDARDIZED PRECIPITATION INDEX (SPI) AND STANDARDIZED PRECIPITATION EVAPOTRANSPIRATION INDEX (SPEI) DROUGHT CHARACTERISTIC AND TREND ANALYSIS USING THE SECOND GENERATION CANADIAN EARTH SYSTEM MODEL (CanESM2) OUTPUTS UNDER REPRESENTATIVE CONCENTRATION PATHWAY (RCP) 8.5, Carpathian Journal of Earth and Environmental Sciences, August 2019, Vol. 14, No. 2, p. 399 - 408; DOI:10.26471/cjees/2019/014/089

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In the era of changing climate, drought assessment and monitoring are vital at the Langat River Basin, a fast-growing region in Peninsular Malaysia with two dams located in the basin. Drought indices Standardized Precipitation Index (SPI) that is solely based on rainfall, and Standardized Precipitation Evapotranspiration Index (SPEI) that considers both rainfall and potential evapotranspiration (PET), were adopted to assess the frequency and severity of droughts in this study. The General Circulation Model (GCM) outputs from the second generation Canadian Earth System Model (CanESM2) under the Representative Concentration Pathway (RCP) 8.5 were statistically downscaled using the Statistical Downscaling Model (SDSM) version 4.2.9 to produce the required regionalized rainfall and temperature data. Both indices with respective time scales of 1-, 3- and 6-month were calculated using observed and the projected climate data. Downscaling results showed that temperature of the basin will increase drastically in 2021-2050. Therefore, PET should not be excluded in drought assessments. It was found that SPI tends to underestimate drought events, and its correlation with SPEI decreases over time. Hence, SPEI, that considers the effect of PET, is more suitable for describing drought events. In general, projected high rainfall reduces the frequency and severity of drought in the Langat River Basin.