Climate analysis at relevant time scales is important for water resources management, agricultural planning, flood risk assessment, ecological modeling and climate change adaptation. This study analyses spatiotemporal variability and trends in rainfall and temperature in Alwero watershed, western Ethiopia. Our analysis is focused on describing spatial and temporal variability of rainfall in the study area including detection of trends, with no attempt at providing meteorological explanations to any of the patterns or trends. The study is based on gridded monthly rainfall and maximum and minimum temperature data series at a resolution of 4 × 4 km which were obtained from the National Meteorological Agency of Ethiopia for the period 1983–2016. The study area is represented by 558 points (each point representing 4 × 4 km area). Mean annual rainfall of the watershed is > 1600 mm. Annual, June–September ( Kiremt ), March–May ( Belg ) rainfall totals exhibit low inter-annual variability. Annual and October-February (Bega) rainfalls show statistically significant increasing trends at p = 0.01 level. May and November rainfall show statistically significant increasing trends at p = 0.01 level. March shows statistically significant decreasing trend at p = 0.1 level. The mean annual temperature of the watershed is 25 °C with standard deviation of 0.31 °C and coefficient of variation of 0.01 °C. Mean annual minimum and maximum temperatures show statistically non-significant decreasing trends. Bega season experienced statistically significant deceasing trend in the maximum temperature at p = 0.01 level. The year-to-year variability in the mean annual minimum and maximum temperatures showed that the 2000s is cooler than the preceding decades. Unlike our expectations, annual and seasonal rainfall totals showed increasing trends while maximum and minimum temperatures showed decreasing trends. Our results suggest that local level investigations such as this one are important in developing context-specific climate change adaptation and agricultural planning, instead of coarse-scale national level analysis guiding local level decisions.

中文翻译：

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埃塞俄比亚西部阿尔韦罗流域降雨和温度的时空变化和趋势

相关时间尺度的气候分析对于水资源管理、农业规划、洪水风险评估、生态建模和气候变化适应非常重要。本研究分析了埃塞俄比亚西部阿尔韦罗流域的降雨和温度的时空变异性和趋势。我们的分析侧重于描述研究区域降雨的空间和时间变化，包括趋势检测，不尝试对任何模式或趋势提供气象解释。该研究基于 1983-2016 年期间从埃塞俄比亚国家气象局获得的分辨率为 4 × 4 km 的网格化月降雨量和最高和最低温度数据系列。研究区域由 558 个点表示（每个点代表 4 × 4 km 区域）。流域年平均降雨量 > 1600 毫米。每年 6 月至 9 月（基雷姆特）、3 月至 5 月（比利时）的降雨总量显示出较低的年际变化。年度和 10 月至 2 月 (Bega) 降雨量在 p = 0.01 水平上显示出统计上显着的增加趋势。5 月和 11 月的降雨量在 p = 0.01 水平上显示出统计上显着的增加趋势。3 月在 p = 0.1 水平上显示出统计上显着的下降趋势。流域年平均气温25℃，标准差0.31℃，变异系数0.01℃。年平均最低和最高温度显示出统计上不显着的下降趋势。Bega 季节的最高温度在 p = 0.01 水平上经历了统计学上显着的下降趋势。年平均最低和最高温度的逐年变化表明 2000 年代比前几十年凉爽。与我们的预期不同，年度和季节性降雨总量呈上升趋势，而最高和最低气温呈下降趋势。我们的结果表明，像这样的地方层面的调查对于制定特定环境的气候变化适应和农业规划很重要，而不是指导地方层面决策的粗略的国家层面分析。