## 6 Conclusions  
The long-term climate data in the upstream, midstream, downstream areas of the Varzob River Basin in Tajikistan have been assessed using original Mann-Kendall test, modified Mann-Kendall test, Sen's slope test, and Pettitt test. The main findings are as follows:1. The trend in mean annual temperature showed a significant increasing trend in all areas in VRB during the period 1991-2018. Almost all months indicated an increasing trend except November and December during the period 1991-2018.
2. The results of the annual precipitation showed a decreasing trend in upstream, mid-stream, and downstream areas, whereas in alpine areas (Anzob station), an increasing trend of annual precipitation was observed from 1960 to 1990. The monthly precipitation showed a significant decreasing trend in April, while January and February showed a significant increasing trend.
3. The trend in the MODIS data showed an increasing trend in snow cover area in April and July, while a decreasing trend was observed in February, September, November, and December during the period 2001-2022 in the VRB. The results revealed that at highly elevated areas, the snow cover area showed a spatially decreasing trend in the winter season. Hushyori station belongs to a low elevated region and showed the decreasing trend during most months. The station measurement-based data indicated the maximum monthly snow cover height in April (178 cm) at the Anzob station and in March at the Maykhura (138 cm) and Hushyori (54 cm) stations.  
A limitation of this study is that we only used the three climate stations that were available in three parts of the basin, and the snow cover based on the measurement was used for 2014. The MODIS data used have a spatial resolution of 500 m, and Landsat and Sentinel snow cover data can be taken into account in future studies. This study will serve as a basis for decision making for impact analysis and more in-depth climate research at the district level. To maintain the livelihoods of Central Asian populations, it is crucial to comprehend how temperature, precipitation, and snow cover have been altered through time and space. Further research could focus on reducing uncertainties and combining climate measurements with global climate model (GCM) data linked to a hydrological model to predict the impact of climate variability on water resources in the VRB.  
All authors were involved in the intellectual elements of this paper. Conceptualization, N.G. and Y.C.; formal analysis and writing--original draft preparation, N.G.; writing--review and editing, A.G.; methodology, Z.S., M.N., R.D. and S.A.; data curation and investigation, M.G. All authors have read and agreed to the published version of the manuscript.  
This study is supported by the National Natural Science Foundation of China (Grant No. U1903208) and the Research Fund for International Scientists of National Natural Science Foundation of China (Grant No. 42150410393).  
Not applicable.  
[PERSON] would like to express his sincere gratitude to the Chinese Academy of Science (CAS) and the World Academy of Science for the Developing World (TWAS) Presidents Fellowship program for international Ph.D. students (Awardee of 2019 CAS-TWAS Presidents fellowship) for the financial support for this study. The authors are thankful to the Ministry of Energy and Water Resources of the Republic of Tajikistan and the Agency of Hydrometeorology of the Committee for Environmental Protection under the Government of the Republic of Tajikistan for providing the data for this research.  
The authors declare no conflict of interest.