Droughts projection over the Niger and Volta River basins of West Africa at specific global warming levels. (24th March 2020)

• Record Type: Journal Article
• Authors: Oguntunde, Philip G.; Abiodun, Babatunde J.; Lischeid, Gunnar; Abatan, Abayomi A.
• Is Part Of: International journal of climatology. Volume 40:Number 13(2020)
• Page Start: 5688
• Page End: 5699
• Publication Date: 2020-03-24
• Subjects: climate change -- drought index -- global warming levels -- river basins -- West Africa -- CORDEX data; Climatology -- Periodicals; Climat -- Périodiques; Climatologie -- Périodiques; 551.605
• DOI: 10.1002/joc.6544
• Languages: English
• ISSNs: 0899-8418

Abstract

Abstract: This study investigates possible impacts of four global warming levels (GWLs: GWL1.5, GWL2.0, GWL2.5, and GWL3.0) on drought characteristics over Niger River basin (NRB) and Volta River basin (VRB). Two drought indices—Standardized Precipitation Index (SPI) and Standardized Precipitation‐Evapotranspiration Index (SPEI)—were employed in characterizing droughts in 20 multi‐model simulation outputs from the Coordinated Regional Climate Downscaling Experiment (CORDEX). The performance of the simulation in reproducing basic hydro‐climatological features and severe drought characteristics (i.e., magnitude and frequency) in the basins were evaluated. The projected changes in the future drought frequency were quantified and compared under the four GWLs for two climate forcing scenarios (RCP8.5 and RCP4.5). The regional climate model (RCM) ensemble gives a realistic simulation of historical hydro‐climatological variables needed to calculate the drought indices. With SPEI, the simulation ensemble projects an increase in the magnitude and frequency of severe droughts over both basins (NRB and VRB) at all GWLs, but the increase, which grows with the GWLs, is higher over NRB than over VRB. More than 75% of the simulations agree on the projected increase at GWL1.5 and all simulations agree on the increase at higher GWLs. With SPI, the projected changes in severe drought is weaker and the magnitude remains the same at all GWLs, suggesting that SPI projection may underestimate impacts of the GWLs on the intensity and severity of future drought. The results of this study have application in mitigating impact of global warming on future drought risk over the regional water systems. Abstract : This study investigates impacts of global warming levels (GWLs: GWL1.5, GWL2.0, GWL2.5, and GWL3.0) on drought characteristics over Niger and Volta River basins. The projected changes in drought frequency were quantified and compared for four GWLs under RCP8.5 and RCP4.5 scenarios. More than 75% of the simulations agree on the projected increase at GWL1.5 and all simulations agree on the increase at higher GWLs. The results of this study have implication for management of drought risk and regional water systems.