Home – Home – Jornals – Geography and Natural Resources 2020 number 3

Soil-erosion processes in the basins of the Tugnui and Sukhara rivers of the Selenga middle mountain region of the Republic of Buryatia were studied. It was revealed that the Tugnui basin is characterized by slope water-erosion, fluvial and aeolian processes. Five soil-erosion areas were identified. It was found that areas of rare, weak, medium and high density and the degree of density of gullies are typical for the southern slopes of the Tsagan-Daban mountain range, the northern slopes of the ridge Zaganskii range, the Tugnuiskii intra-depression low-mountain range, the river valleys, and the treeless cultivated areas. The gullies are affected by sub-mountain deluvial-proluvial aprons occupying the most extensive areas on the bottom of the depression, the ledges and surfaces of river terraces, and the bottoms of balkas. Toward the mountains surrounding the depression, the density and the degree of density of gullies decrease considerably. Territories with the degree of linear dissection ranging from 0,07 to 0,25 km/km ² and the density of gullies varying from 0,13 to 0,51 gully/km ² were identified. Compared to the deflation processes, the middle part of the Tugnui steppe region and the areas within the basins of the Barka, Galtai and Sutai rivers were severely destroyed by gullies. The base level of erosion in this locality is more than 400 m, according to absolute elevations the watersheds (average value) and the elevation at the mouth. Different groups of gullies were identified according to the distribution of gullies along the length, and to the indicator of the intensity of the erosion processes. It was found that most of the gullies with a length of more than 600 m are in the stage of rest, increasing more in volume and sometimes in length, due to the growing small side gullies holes, and the most widespread types are slope and bottom, and more rarely, less often coastal scours. It was found that the determining factors in the development of gullies of these types include the occurrence of slopes with a steepness of 3-5°, the complexity of the terrain, the heterogeneity of soil-forming materials, the occurrence of thick loose deposits, rain precipitation of significant intensity, and high agricultural development. It is estimated that the total length of the scours in the basins of the Tugnui and Sukhara rivers is 834 km, with 480 km of them corresponding to the gully network in the most plowed valley of the Tugnui river which has a catchment area of 2770 km ² .