Journal of Water and Climate Change (Nov 2022)
Comparative analysis of long-term precipitation trends and its implication in the Modjo catchment, central Ethiopia
Abstract
Understanding trends and variability of precipitation is essential to improve water resources utilization as well as agricultural activities. This study aims to investigate the spatiotemporal trends and variability of rainfall in the Modjo watershed, central Ethiopia. The Mann-Kendall trend (M–K) test, innovative trend analysis (ITA) and Sen's slope estimator were used to determine temporal trends, while the inverse distance weighted interpolation technique was adopted to visualize the spatial trends in time series. The result showed that complex patterns of rainfall variability that range from 16 to 59%, 18 to 63%, and 50 to 90% for the annual, summer, and spring seasons, respectively was observed over the study watershed. The result also indicated that significant trend (p 0, SITA > 0), whereas negative trends (Z < 0, SITA < 0) were detected in the spring season. Comparatively, the ITA method is found to be robust and allows more detailed trend analysis results using graphical illustrations for extreme events. The study concludes that the increasing and decreasing trends in summer and spring rainfall patterns could have implications leading to an increase in extreme events and lower agricultural productivity, respectively. The result suggests the need for planning effective adaptation strategies at the regional and local scales. HIGHLIGHTS Comparative trend analysis approach was followed using the classical M–K test and ITA method.; The spatiotemporal trend is analyzed at station level which is not a common approach.; The study indicates the ITA method displays more significant trends than the M–K test.; Increasing extreme events and lower agricultural productivity were identified as the major implications in the future.; Establishing effective adaptation strategies in such a rain-fed agricultural watershed is needed.;
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