Spatiotemporal variability and trends of precipitation, temperature, and evapotranspiration in the Muger sub-basin of the Abbay basin Ethiopia

Abstract

This study used time series data from 1980 to 2022 to investigate spatiotemporal changes and trends of precipitation, temperature, and evapotranspiration in Muger sub-basin. The coefficient of variation (CV), precipitation concentration index (PCI), and seasonality index (SAI) were used to assess variability, while the Mann–Kendall test, Sen’s slope estimator, and innovative trend analysis (ITA) were applied to detect and quantify trends in climatic variables. Seasonally, the CV was highest in the winter season, indicating strong rainfall variability. Irregular rainfall distribution was observed at Debre Berhan station, as indicated by high PCI values. The SAI results show that the Muger sub-basin alternates between dry and wet conditions for both temperature and rainfall. The maximum significant increasing trend ( P  < 0.05) in annual rainfall was recorded at Gerba Guracha station (Z = 2.74, S = 8), while a significant decreasing trend was observed at Jeldu station (Z = − 3.28, S = − 23.26). The annual maximum temperature showed, the maximum significant increasing trend 0.038 °C/year recorded at Addis Ababa station. The minimum temperature reveals the maximum significant increasing trends across all seasons, with rate of 0.013 °C/year in winter, 0.046 °C/year in the spring, 0.033 °C/year in the summer, and 0.025 °C/year in the autumn. Sen’s slope revealed a maximum increasing rate 5.89 mm/year, whereas ITA of annual rainfall reveals upward and downward tendency at low, medium, and high cluster categories. All stations displayed an upward trend in annual ET 0 , with exception of Jeldu station, which had a magnitude of (− 6.195 mm/year). The rising trend in ET 0 could be the result of increasing temperature during the 1980–2022 period, further increasing stress on water resources. These changes indicate ongoing climate variability in the sub-basin, which may have important information for water resource availability and agricultural planning strategies in the Muger sub-basin.