Local climate change indications: Historical trends, multi-model projections and implications in Bilate Catchment, Southern Ethiopia

Abstract

Climate change is a major factor affecting hydrologic processes, water resources and agricultural productions in a catchment. This study aimed to evaluate the historical trends, future climate changes, characteristics of heat waves, dry and wet months in Bilate catchment, southern Ethiopia. The Mann-Kendal, Theil-Sen estimator were employed to analyse the trends and magnitude of trends of historical temperature and rainfall. Ensemble mean of regional climate models (RCMs) was employed for the future climate projections of this (2021-2050), mid (2051-2070), and end (2081-2100) centuries relative to baseline (1981-2010). Results revealed that the change in temperature under RCP4.5 and RCP8.5 showed an increase in the three future periods. Under the scenarios, the monthly maximum temperature is projected to increase in the range of 0.1 to 2.4 °C and 0.1 to 4.2 °C, respectively. Likewise, the minimum temperature is in the range of 0.1 to 1.9°C and 0.3 to 3.5 °C. Under the scenarios, seasonal rainfall is projected to increase in the range of 124 to 3,009.9 mm and 52.5 to 1111.0 mm; while decreases are from -19.4 to -1679.3 and -243.3 to -2,444.7 mm, respectively. Besides, dry months and heat waves are expected to increase. The combined effect of a reduction in rainfall, increase in heat waves and dry months will likely impact on the people whose livelihood depend on rain-fed subsistence agriculture in the catchment. Water and crop yield reduction are the major implications in this century. These findings raise awareness about the impacts of climate change in the community and regional authorities to endorse development policies.