## 3 Results
### Trend and Variability of Rainfall and Temperature
#### 3.2.1 Trend and Variability of Rainfall  
In Sawena district, by analyzing rainfall (Table 3) the Mann-Kendall test results for monthly rainfall revealed a significant increasing trend in September (MKS = 84), October (MKS = 246), and November (MKS = 118), with the Sen's slope value showing annual changes of 0.096 mm, 1.284 mm, and 0.072 mm, respectively, at the 0.05 and 0.01 significance levels. October had the most pronounced upward trend, with a Sen's slope of 1.284 mm/year. March and August also showed an upward trend in rainfall, with increases of 0.136 mm and 0.067 mm per year, though these were not statistically significant. Similarly, January, February, April, May, June, July, and December showed decreasing trends in rainfall, but none of these trends were statistically significant.  
Regarding rainfall variability, January and February experienced the highest variability, with a fluctuation of 242.05% and 232.22%, respectively, indicating that rainfall in these months is highly inconsistent from year to year. In contrast, April showed the lowest variation at 38.1%, suggesting more stable and consistent rainfall during that month.  
During the winter season, as Table 4 indicated. rainfall variability is high, with a coefficient of variation of 126.75%, indicating substantial fluctuations in rainfall amounts from year to year. In contrast, spring experiences relatively low variability, with a coefficient of 32.25%, reflecting more consistent and stable rainfall patterns. Despite this stability, there is no significant trend in spring rainfall, as shown by a Kendall's tau of \(-0.105\) and a \(p\)-value of 0.345.  
Rainfall variability during summer and autumn is moderate, with coefficients of 56.49% and 57.84%, respectively. While both seasons exhibit similar levels of fluctuation, only autumn shows a significant increasing trend in rainfall, whereas summer does not. This suggests that autumn is becoming wetter over time, while the other seasons remain largely unchanged. A graphical representation of the rainfall trends in Sawena district is presented in Figures 2-6.  
Figure 2: Trend of winter season rainfall.  
\begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline
**Item** & **Mean Annual RF** & **Std. Deviation** &
\begin{tabular}{c} **Coefficient of** \\ **Variation** \\ \end{tabular} & **Kendall’s Tau** & **MK-Statistic (S)** & \(p\)**-Value** & **Sen’s Slope** \\ \hline Month & & & & & & & \\ January & 2.74 & 6.620 & 242.05 & \(-\)0.072 & \(-\)51 & 0.546 & 0.000 \\ February & 5.93 & 13.777 & 232.22 & \(-\)0.018 & \(-\)12 & 0.892 & 0.000 \\ March & 31.34 & 33.716 & 107.57 & 0.041 & 32 & 0.718 & 0.136 \\ April & 41.04 & 38.499 & 38.100 & \(-\)0.062 & \(-\)48 & 0.584 & \(-\)0.302 \\ May & 58.67 & 32.695 & 55.720 & \(-\)0.062 & \(-\)48 & 0.584 & \(-\)0.351 \\ June & 7.53 & 10.150 & 134.66 & \(-\)0.083 & \(-\)65 & 0.456 & \(-\)0.035 \\ July & 12.71 & 10.903 & 85.780 & \(-\)0.012 & \(-\)9 & 0.926 & \(-\)0.008 \\ August & 9.12 & 9.754 & 106.98 & 0.090 & 70 & 0.421 & 0.067 \\ September & 61.90 & 12.397 & 104.17 & 0.108 & 84 & 0.034 * & 0.096 \\ October & 44.80 & 41.643 & 92.953 & 0.315 & 246 & 0.004 * & 1.284 \\ November & 75.27 & 42.045 & 55.853 & 0.216 & 118 & 0.047 ** & 0.072 \\ December & 10.33 & 17.227 & 166.80 & \(-\)0.153 & \(-\)161 & 0.173 & \(-\)0.975 \\ Season & & & & & & \\ Winter & 18.99 & 24.077 & 126.75 & \(-\)0.159 & \(-\)124 & 0.152 & \(-\)0.129 \\ Spring & 191.06 & 61.626 & 32.253 & \(-\)0.105 & \(-\)82 & 0.345 & \(-\)1.044 \\ Summer & 29.36 & 16.588 & 56.490 & 0.064 & 50 & 0.568 & 0.117 \\ Autumn & 131.97 & 76.340 & 57.843 & 0.208 & 162 & 0.041 * & 1.935 \\ Annual & 371.40 & 102.214 & 27.521 & 0.062 & 48 & 0.449 & 0.653 \\ \hline \hline \end{tabular} Source: own computation; ** and * indicate 5% and 1% levels of significance, respectively.  
\end{table}
Table 4: Mann–Kendall trend analysis of rainfall in Sawena district (1984–2023).  
Figure 3: Trend of spring season rainfall.