## 2 Study Area  
The Varzob River Basin is located in the southwest of Tajikistan. It is formed by the confluence of the rivers Ziddi and Myakhura [41]. The length of the river is 71 km [42]. The Varzob River Basin covers an area of 1740 km\({}^{2}\)[43]. The VRB's territory has a significant economic impact on the nation. The city of Dushanbe is situated on the extensive terraces of the Dushanbinka River's lower reaches (capital of Tajikistan). As a passageway to the high- mountainous region of Central Tajikistan and the basin of the upstream and midstream regions of the river, the Varzob gorge cuts over the southern slope of the Gissar Range [41]. Zeravshan, which is situated in the Fergana intermountain valley, is the only exit from the south to the republic's northern areas. Due to its dependence on the height of the sun above the horizon and the length of solar illumination of the Earth's surface, the latitudinal position is of critical physical and geographical significance. The vast continental massif of Eurasia contains the Varzob River Basin. It receives atmospheric moisture from Atlantic Ocean which is thousands of kilometers away. The formidable Hindu Kush chain blocks access to the Indian Ocean, which is located approximately 1400-1500 km away [44]. All of this comes together to establish the primary characteristics of the climate of the land as well as the denudation processes that take place on it. Because of the great distance that separates it from the primary regions that contribute moisture to the atmosphere, the basin features a distinctly continental climate. As a result of its location on the southern slope of the Gissar Range and the foothills of that range, the VRB has a large southern exposure, and the surface of the land that is the focus of this analysis faces south. This also has an effect on the processes that are involved in denudation as well as the conditions that are necessary for the production of denudation relief. The orographic core of the basin is the gorge of the river. The Varzob River Basin is stretched in a meridional orientation from north to south. It creates two halves that are roughly equivalent to one another within the basin. The Ziddi and Maykhura rivers form the Varzoba River in the middle reaches, close to the village Gushary on 1890 m a.s.l. [45] This location is at the foot of the axial part of the Gissar Range (1100 m) [42]. The elevation of Kofarnihon River is 720 m [8]. That is a drop of 1200 m over approximately 55 km. Although the Ziddi and Maykhura rivers form the Varzob River, originating at an elevation of 3700-3800 m, the actual drop is significantly greater [42]. The transverse character of the gorge changes in the higher sections of the Varzob, ranging from V-shaped to a classic canyon with vertical slopes. Short routes have relative heights of 1500-2000 m [43]. There are no conditions for the formation and preservation of accumulative terraces. Massive scree cones with avalanche origins descend to the river almost everywhere along the gorge's slopes. The river frequently alters its grade [45]. Figure 1 shows the study area and the locations of the climate station in the VRB. The valleys of the Varzob's large tributaries resemble essentially identical great gorges formed by erosion to the main valley. Among these are the valleys of the rivers Ziddi, Maikhura, Sioma, Gurke, and Varzobi-Bolo, as well as the valleys of their individual constituents Diamalik and Takob, Obidzhuk, and Luchob [44]. Some of them, such as the Maykhura, Sioma, and Ziddi rivers, as well as their tributaries, have characteristic glacial valleys in their higher stages (trogs) [42]. The Varzob River significantly affects the runoff and water content of the Kofarnihon River Basin. The main runoff (80%) of the Kofarnihon River is formed in the right-bank part of the basin, on the southern slope of the Gissar Range [46].