## 4 Results
### Precipitation Analysis in the Varzob River Basin  
Figure 5 indicates the monthly precipitation changes in upstream, midstream, and downstream areas of the VRB. The annual amount of precipitation is 494 mm at Anzob station. The Anzob region is characterized by an annual course of precipitation reaching its minimum in August-September and its maximum in March-May. Annually precipitation mostly (44%) falls in the spring, 26% falls in winter, and 13-17% falls in the summer and autumn months. The average annual relative humidity is 65% and the average monthly ranges from 50 to 80%. Considering the second period (1991-2018), we can say that the period of precipitation has partially changed in temporal precipitation, as there was an increase in precipitation in February and March and a decrease in April. In mountainous terrain, precipitation forms mudflows on the river during the periods of late autumn and during spring floods. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Anzob Average Temperature (\({}^{\circ}\)C)**} \\ \hline Period & Change Point & Sen’s Slope & \begin{tabular}{c} Original MK \\ Test Z-Value \\ \end{tabular} & \
\begin{tabular}{c} Modified MK \\ Test Z-Value \\ \end{tabular} & \(p\)-Value &
\begin{tabular}{c} Significance Based on \\ the Modified MK Test \\ \end{tabular} \\ \hline
1961–1990 & 1976 & 0.019 & 1.356 & 5.775 & 0 & *** \\
1991–2018 & 2007 & \(-\)0.00064 & 0 & 0 & 1 & NS \\
1961–2018 & 2007 & 0.002 & 0.489 & 1.067 & 0.285 & NS \\ \hline \multicolumn{6}{c}{**Maykhura Average Temperature (\({}^{\circ}\)C)**} \\ \hline Period & Change point & Sen’s slope & \begin{tabular}{c} Original MK \\ Test Z-Value \\ \end{tabular} & \
\begin{tabular}{c} Modified MK \\ Test Z-Value \\ \end{tabular} & \(p\)-value &
\begin{tabular}{c} Significance Based on \\ the Modified MK Test \\ \end{tabular} \\ \hline
1964–1990 & 1976 & 0.034 & 0.242 & 6.695 & 0 & *** \\
1991–2017 & 2000 & 0.065 & 3.835 & 9.331 & 0 & *** \\
1964–2017 & 1998 & 0.028 & 4.103 & 8.542 & 0 & *** \\ \hline \multicolumn{6}{c}{**Hushyori Average Temperature (\({}^{\circ}\)C)**} \\ \hline Period & Change point & Sen’s slope & \begin{tabular}{c} Original MK \\ Test Z-value \\ \end{tabular} & \
\begin{tabular}{c} Modified MK \\ Test Z-value \\ \end{tabular} & \(p\)-value &
\begin{tabular}{c} Significance Based on \\ the Modified MK Test \\ \end{tabular} \\ \hline
1960–1990 & 1971 & \(-\)0.004 & \(-\)0.187 & \(-\)0.839 & 0.401 & NS \\
1991–2018 & 1998 & 0.05 & 3.32 & 6.224 & 0 & *** \\
1960–2018 & 1998 & 0.015 & 2.825 & 5.032 & 0 & *** \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Annual air temperature trends, Sen’s slope, change point (Petti’s test), as well as the original and modified Mann–Kendall (MK) tests for the trends (Z) in the upstream, midstream, and downstream regions of the Varzob River Basin in Tajikistan during three time periods (1960–1990, 1991–2018, and 1960–2018). At the Maykhura station, the annual amount of precipitation is about 1185 mm. The Maykhura meteorological station area is characterized by an annual precipitation pattern with a maximum in March (1964-1990) and in February and March (1991-2018) and a minimum in August-September. Most of them fall from December to April. According to the analysis and monitoring of precipitation during the period 1960-1990 at Maykhura station, it can be said that March is considered the most intense month in terms of precipitation, and August is considered the least water. Considering the second period (1991-2018), we can say that the period of precipitation has partially changed in temporal precipitation, as there was an increase in precipitation in February and March and a decrease in April. At Hushyori station, the annual amount of precipitation is 1188 mm. The station is characterized by an annual course of precipitation with a minimum in August-September and a maximum in March. Their main amount of 45% falls in the spring, 35% falls in the winter, and 5-15% of the annual precipitation falls in the summer and autumn months.