Time series trend analysis of temperature and rainfall in lake Tana Sub-basin, Ethiopia

Abstract

Background: To identify and quantify the impact of climate change on socioeconomic sectors and ecosystems, many global studies have been carried out and policy changes for mitigation and adaptation were recommended. However, the old-fashioned top-down approach, global study, has little local and regional specificity and has failed to address the regional and local consequences of climate change. Thus, this research was conducted in filling such knowledge gaps in Lake Tana sub-basin. The research was aimed at addressing the national and local issues of climate change and was done by analyzing time series temperature and rainfall trends in the highlands of Ethiopia and LTSB in particular. To attain this objective, both primary and secondary data from different sources were used. The collected data were analyzed following quantitative and qualitative analysis methods and Manna Kendall Trend test method was used. Results: The main findings revealed that the mean, maximum and minimum temperature had a general increasing trend; whereas, rainfall amount showed a general decreasing trend in Lake Tana Sub-basin. Analysis of the 40 years annual total rainfall data from 109 representative ground based meteorological stations in Ethiopia indicated a coefficient of variation ranging from 20 to 89 %. Of the 109 stations considered, 17 had above 42 % coefficient of variation highlighting the extreme variability of rainfall over the country Conclusions: To conclude, development planners should design strategies and plans by taking into account a declining summer rainfall and increasing temperature impacts on rural livelihoods.