Formation of the asymmetric pattern of a river lithological catchment basin in relation to specific features of the tectonic structure of the territory

Abstract

A digital terrain model of the Izh River lithological catchment basin located within the Russian Plain was developed on the basis of the ESRI ArcGIS 10.4 technologies using the SRTM 30 data. The Hydrology tool of the Spatial Analyzer set was applied to vectorize the river network and boundaries of the individual catchments forming the Izh River basin. The basin area was evaluated by a complex of morphometric indicators, such as geometrical indices (the area, the basin length, and width, the length of erosion network, the roundness coefficient) and geomorphologic indices (mean absolute elevation of the basin and the altitudinal difference, the basin slope, gradient and density of the river network, the energy of relief). The analysis of morphometric indices proved that the right bank is structurally most pronounced in relief and differs from the relatively flattened left bank in a number of indicators, namely absolute elevation difference, surface slope, gradient of the river network, and ruggedness of relief. The highest asymmetry coefficient suggests the asymmetric configuration of the basin which is due to the left-hand shift of the catchment towards the right bank. The spatial analysis of geological-tectonic organization of the basin revealed heterogenic tectonic structures and showed the correlation of relief structure of the Izh River with the spatial pattern of tectonic structures. It is argued that the basin asymmetry is, on the one hand, due to the difference in tectonic structures of its right and left bank areas, and, on the other hand, owing to the intrusion of several right-bank tributaries of the Kama River, which is the main watercourse of the 1st order, into the left-bank part of the Izh River basin. Thus, it is shown that the asymmetry of the basin could be explained by the presence of tectonic contacts, which separate geological structures different in lithological composition, genesis and age, in which the rivers have channeled their ways.