Morphometric features of the structure of river basins Oina-Kharal ore node (Tuva, Russia)

The article presents a morphometric and fractal analysis of the river basins of the Kharal river and the OO-Khem river of the Oina- Haral ore node based on the Horton-Straler classification using geographical information system (GIS) methods. The analysis was performed on maps digitized at a scale of 1: 100 000. The morphometric characteristics under study, such as the number, orders of watercourses, and their length, were directly calculated in the ArcGIS program. The fractal dimension indicator was calculated using the software "Fractal dimension of the river network". A morphometric and fractal model of the catchment area has been tested. Morphometric analysis is performed by measuring linear parameters and allows us to observe qualitative and quantitative changes in the definition of the catchment area, taking into account the logarithmic scale of the number, length and average length of river watercourses of different orders. The advantage of the fractal model is that it requires only the values of the fractal dimension of river streams of different orders. The obtained morphometric and fractal models of rivers Kara-Khem, Chayyndy, Ak-Khem and Demerzhi reflect their implementation, and in the catchments of the rivers Shorlug, Sai-Kezhig, Oinaa, Kara-Adyr, Shennelig should be more river sections 2 and 3-th order. Analysis of the equilibrium index for the Kharal and Oo-Khem river basins indicates that the rivers of this basin are not in equilibrium, they have a relative degree of underdevelopment, except for the Chayynda river, which is over-developed (In = 1.4). The state of the imbalance is confirmed by fractal analysis, which indicates that river basins of the 4th order have watercourses of order 4, with a fractal dimension higher than those of the 3rd order. The reason is that the modern river network of the Oo-Khem river and the Kharal river is at a young stage of development, characteristic of mountain rivers; active deep and lateral erosion continues here, the longitudinal profiles are not developed. This is due to the complex history of basin development, with multiple changes in the bases of erosion caused by glaciation, with the restructuring of the river network and interception of rivers that occurred in the upper Pleistocene period due to the melting of the ice cover. The bifurcation coefficient of the river basins of the study area has the highest value for the flow of the 1st and 2nd orders, but decreases in the flow of the 3rd and 4th orders, since it is not affected by any structural control. The quantitative analysis of morphometric parameters can help to reveal the climatic, geomorphological, structural and geological features of the territory. From a theoretical point of view, this research makes a certain contribution to the development of fractal methodology for further accumulation of texture material. Within the Oina-Kharalsky ore node, testing of morphometric and fractal analysis of the river basins of the Kharal river and the Oo-Khem river can be used to predict and identify new placer gold deposits in the elements of the ancient river network.

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