## 4 Results
### Snow Cover Analysis in the Varzob River Basin
The flow of the river during this period is considered the most complete and full-flowing. The coldest months were February and December at Anzob station with a mean daily temperature of \(-15\)\({}^{\circ}\)C, and the warmest temperature was recorded in July at +10.1 \({}^{\circ}\)C. At the same time, the snow cover lay until June, i.e., it can be said that the last natural recharge of the river runoff ends in June and precipitation in the form of rain wash away the remnants of the snow cover. The accumulation of snow cover occurs from October and continues until the beginning of April, and then, precipitation in the form of rain begins to wash away the accumulated snow cover, which has a beneficial effect on the runoff of the Varzob River. During the low-water period (July, August, September), the precipitation does not have a special effect on the increase in the river flow. Figure 7: The annual precipitation change points during the periods of (**a**,**d**,**g**) 1960–1990, (**b**,**e**,**h**) 1991–2018, and (**c**,**f**,**i**) 1960–2018 based on the Pettitt’s test at Anzob, Maykhura, and Hushyori meteorological stations in the upstream, midstream, and downstream areas of the Varzob River Basin in Tajikistan. The Maykhura snow avalanche station in the midstream region (Figure 8b) is the only station located in the Varzob River Basin at an elevation of 2000 m.a.s.l. As shown in Figure 6, the maximum height in snow cover occurs in March, when the maximum snow height reaches almost 138 cm. Snow cover is observed all year for almost six months and only six months--the low-water period is considered to be almost zero (with the possible loss of small precipitation in the form of rain). Thus, we note that the snow cover appears in the first ten days of November and is practically unstable. Wet-dry snow begins to accumulate in December when the temperature is firmly in minus weather. The sub-zero temperature firmly holds the snow crust until the onset of spring. The coldest months at Maykhura station were January, with a mean daily temperature of \(-\)6.1 \({}^{\circ}\)C, and the warmest temperature was recorded in July at +19.4 \({}^{\circ}\)C. At the same time, the snow cover lay until May, i.e., it can be said that the last natural recharge of the Varzob river runoff ends in May. Figure 8: The monthly changes of the snow cover, temperature, and precipitation in the upstream, midstream, and downstream regions in 2014 in the Varzob River Basin in Tajikistan. We analyze the period of the accumulation of snow cover in the lower parts of the Varzob river. At Hushyori station, the maximum increase in snow cover occurs in February, when the maximum snow height reaches almost 54 cm (Figure 8c). These data are considered the average value for three rails installed at the meteorological site. Snow cover is observed all year around for almost five months and the low-water period is considered to be almost zero (with possible slight precipitation in the form of rain) for only seven months. Snow cover appears in the last ten days of November and is practically unstable. Wet-dry snow begins to accumulate in December when the night temperature is firmly in below zero. At Hushyori station, the temperature is below zero only in February--this is the coldest month with a mean daily temperature of \(-2.4\)\({}^{\circ}\)C, and the warmest temperature was recorded in July at +24.2 \({}^{\circ}\)C. At the same time, the snow cover lay until April, i.e., it can be said that the last natural recharge of the river flow ends in March in VRB and the observed precipitation in the form of rain washes away the remnants of the snow cover. The highest snow is observed in the high-mountain zone (Anzob area) of the Varzob River Basin, with a maximum snow height exceeding 2.5 m. Snow saturation occurs in winter during unstable weather and fog formation, as well as in February-March at positive daytime temperatures. [PERSON] et al. [61] studied the snow cover dynamics in the Amu Draya and Syr Darya River Basin in Central Asia.