## 4 Results
### Snow Cover Analysis in the Varzob River Basin  
Here, we described how dependent the river runoff is on snow reserves and trace its maximum runoff and low water period. Let us conduct a small study according to the Anzob meteorological station, which is the only station located in the Varzob river basin at an elevation of more than 3000 m.a.s.l. As can be seen in Figure 6, the period of maximum snow cover growth occurs in April, when the maximum snow height reaches 178 cm. Note that these data are considered to be the average of three rails installed at the meteorological site. This value is considered optimal for long-term data. There are periods with maximum snow height above two meters (240 cm along one of the rails installed at the meteorological site) and here you need to make allowances for the wind, which plays a role in the horizontal transfer of snow cover. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Anzob Precipitation (mm)**} \\ \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 & (-) & 0.481 & 0.186 & 0.632 & 0.527 & NS \\
1991–2018 & 1999 & \(-\)5.615 & \(-\)1.639 & \(-\)2.844 & 0.004 & *** \\
1960–2018 & 1994 & \(-\)1.343 & \(-\)1.752 & \(-\)3.521 & 0 & *** \\ \hline \multicolumn{6}{c}{**Maykhura Precipitation (mm)**} \\ \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 & 1969 & \(-\)7.794 & \(-\)1.167 & \(-\)4.174 & 0 & *** \\
1991–2018 & 1994 & \(-\)6.33 & \(-\)1.027 & \(-\)3.371 & 0 & *** \\
1964–2018 & 1993 & \(-\)3.262 & \(-\)1.604 & \(-\)6.064 & 0 & *** \\ \hline \multicolumn{6}{c}{**Hushyori Precipitation (mm)**} \\ \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 & 1969 & \(-\)1.01 & \(-\)0.204 & \(-\)0.596 & 0.551 & NS \\
1991–2018 & 2004 & \(-\)4.325 & \(-\)0.968 & \(-\)3.754 & 0 & *** \\
1960–2018 & 1986 & 0.925 & 0.477 & 1.879 & 0.06 & * \\ \hline \multicolumn{6}{c}{The significance levels tested are *** for \(p<0.001\), ** for \(p<0.01\), * for \(p<0.01\), * for \(p<0.05\), NS for \(p\geq 0.1\).} \\ \end{tabular}
\end{table} 
Table 5: Annual precipitation trends, Sen’s slope, change point (Pettti’s test), as well as original and modified Mann–Kendall (MK) tests for the trends (Z) in the upstream, midstream, and downstream meteorological stations in the Varzob River Basin in Tajikistan during three time periods (1960–1990, 1991–2018, and 1960–2018). Before beginning the analysis for this part, it should be noted that we chose the data for 2014 for demonstration purposes due to the availability of snow cover data from the measurement-based weather station for a limited period of time. As shown in Figure 8a, snow cover is observed all year around for almost nine months and only three months--when the low-water period is considered to be almost zero (with possible precipitation in the form of rain). Thus, we observed that the snow cover appears in early October and practically does not melt after that. Wet-dry snow begins to accumulate in the high-mountainous part of the Varzob River and the fall of this snow does not affect the overall flow of the river. The sub-zero temperature firmly holds the snow crust until the spring, when the warm rays of light begin to saturate the snow cover with warmth in the daytime and \"squeeze out\" the resulting water at night.