Spatiotemporal variability and trends of rainfall and temperature in the Northeastern Highlands of Ethiopia

Abstract

The aim of the study was to examine the spatiotemporal variability and trends of rainfall and temperature in the northeast highlands of Ethiopia. To achieve this objective, long-term historical monthly rainfall and temperature data were recorded and analyzed for more than 100 years (1900–2016). Gridded rainfall and temperature data were gathered from CenTrends Great Horn of Africa v1 and CRU_TS 4.01 with a resolution of 0.1° × 0.1° and 0.50 × 0.5°, respectively. The Mann–Kendall test was used to analyze the trends of rainfall data in different recording stations, and the Sen’s slope estimator was used to determine the magnitude of change. The Inverse Distance Weighted spatial analysis tool was used to illustrate the spatial trends of rainfall and temperature. The results of the coefficient of variation revealed that the decadal, annual and seasonal rainfall distributions were varied though belg rainfall found to be more variable than the others. The MK test result demonstrated that belg and annual rainfall exhibit a decreasing trend as compared to kiremt rainfall. The distribution of kiremt, belg and annual rainfall demonstrated decreasing trends at a rate of 0.432, 0.335 and 0.595 mm/year, respectively. The decadal rainfall also showed a decreasing trend at the rate of 6.537 mm/decade. On the other hand, the averages of annual, maximum and minimum temperature were increased at the rate of 0.0034, 0.0028 and 0.0095 °C/year, respectively. The decadal minimum, maximum and average temperature has shown increasing trend at the rate of 0.098 °C, 0.041 °C and 0.069 °C, respectively. An abrupt declined rainfall and increased temperature were observed since the 1970s. Climate variability strongly affects rain-fed agriculture more than any other activities. Hence, policymakers and stakeholders have to give top priority in the designing and introduction of appropriate area-specific adaptive strategies to reduce the impacts on crop production over livelihood zones. Rainwater harvesting and the development of small-scale irrigation schemes could be taken as viable options where rainfall is scarce and more variable.