Projections of future rainfall and temperature using statistical downscaling techniques in Tana Basin, Ethiopia
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(2020) 6:77
ORIGINAL ARTICLE
Projections of future rainfall and temperature using statistical downscaling techniques in Tana Basin, Ethiopia Hailu Birara1 · R. P. Pandey2 · S. K. Mishra1 Received: 23 August 2019 / Accepted: 10 August 2020 © Springer Nature Switzerland AG 2020
Abstract Global climate changes are becoming main threats to hydrological cycle, which thus influence environmental, social, and economic systems. Climate change studies using global climate models (GCMs) are mostly used for mitigation and adaptation strategies regarding the changing climate. The current GCMs’ data are, however, too coarse to use directly at the regional and local scales for climate change studies. Two widely used statistical downscaling methods, namely LARS-WG and SDSM models, were used to study the current and future climate change of Tana Basin, Ethiopia. Four GCMs (GFCM21, HadCM3, MPEH5, and NCCCS) for LARS-WG and two GCMs (HadCM3 and CanESM2) for SDSM with different emission scenarios were evaluated. Overall results indicated an acceptable response of the models to simulate and forecast climatic variables under HadCM3 and CanESM2 GCMs. Rainfall results downscaled by LARS-WG from the four GCMs indicated high intermodal variabilities and non-consistence; Increasing trend of rainfall showed on three of the GCMs while one GCM showed a decreasing trend in the range of − 9.6% to 45.2%. The four GCMs rainfall average ensemble value showed an increasing trend ranging from 3.9% to 18.8%, which is also consistent with HadCM3 projections ranging from 4.1% to 19.2%. However, the downscaled results from all four models showed increasing maximum and minimum temperature for all time periods. The mean annual maximum and minimum temperature change increased from 0.9 °C to 2.9 °C and 0.6 °C to 2.5 °C, respectively, while annual mean relative change of rainfall ranged from 9.9% to 44.7%. Both SDSM and LARSWG methods were obtained good monthly rainfall data series than daily rainfall data series in the study area. However, both models with the selected GCMs (HadCM3 and CanESM2) performed reasonably well to simulate temperature than rainfall. Keywords Statistical downscaling model · GCMs · LARS-WG · SDSM · Tana basin · Ethiopia
Introduction Climate change is becoming one of the significant environmental, economic, and social threats to the world. Since 1950, a decrease in the amount of snow, a heating ocean, and rising sea levels have been noticed as results of climate system warming (Intergovernmental Panel on Climate Change [IPCC] 2014). This changing climate affects water resources, especially in tropical regions (Beecham et al. 2014). The climate system has been influenced by human-induced forces * Hailu Birara [email protected] 1
Department of Water Resources Development and Management, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
National Institute of Hydrology Roorkee, Roorkee, Uttarakhand 247667, India
2
activities for centuries. However, the impact of human activities started to extend
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