Statistical downscaling (Delta method) of precipitation and temperature for Bilate watershed, Ethiopia

Abstract

It is important to investigate potential changes in temperature and precipitation for assessing the impacts of future climate change on agricultural production for specific regions. In this study, climate scenarios of precipitation and temperature for the bilate watershed were generated. Statistical downscaling techniques of the Delta method analysis protocol of the Agricultural Intercomparison and Improvement Project (AgMIP) was used to project the future climate state in the farm lands of Bilate Watershed. In this study, climate change scenarios were generated for two Representative Concentration Pathways (RCPs): RCP 4.5 and RCP 8.5 using 20 GCMs from CMIP5 bias-corrected under three future time slices; near-term (2010-2039), mid-century (2040-2069) and end-century (2071-2099). Rainfall is projected to increase in total amount under all-time slices and emissions pathways but with pronounced inter and intra-variability. Minimum temperature will significantly increase during mid-century by 1.81°C (RCP 4.5) and 2.55°C (RCP 8.5) and by 2.1°C (RCP 4.5) and 4.27°C (RCP8.5) during end-century relative to the baseline. The projected increase in maximum temperature during mid-century is 1.43°C under RCP 4.5 and 1.99°C under RCP 8.5 and during end-century by 1.65°C under RCP 4.5 and 3.5°C under RCP8.5 during end-century. Key words: Agricultural Intercomparison and Improvement Project (AgMIP), climate change, Delta method, Global climate models (GCMs), statistical downscaling, watershed.