Structural and Morphometric Analysis of the Ihe-Ukhgun Small River Basin (Irkut River Basin)

Abstract

The article is devoted to the structural and morphometric analysis of a small rivers using the example of the Ihe-Ukhgun river basin (left tributary of the Irkut river), which is based on a complex processing of a digital elevation model (DEM). The author has prepared a hydrologically correct DEM based on the ALOS Digital Surface Model (DSM) satellite data, carried out an automated calculation and mapping of the basin erosion network based on the DEM data, calculated the structural indicators of the third-order basins for analyzing the basin organization of the small rivers network. Structural and morphometric analysis using GIS was practically not used for the Ihe-Ukhgun river basin which is placed in different landscapes, geological and geomorphological conditions. The work is based on geomorphometric and structural morphometric methods as well as the method of geoinformation mapping and relief modeling for analyzing lower-order basins. Thalweg erosion network modeling up to the fourth order of the river basin Ihe-Uhgun was carried out with using of DEM analysis in the ArcGIS 10 program. The map of the erosional network of the basin was constructed, morphometric indicators of rivers (length, area of basins, sum of slopes, coefficient of basin asymmetry, etc.) were obtained, and then the indices of the basin structure (structure of bifurcation, lengths, areas and slopes) were calculated. As a result, an asymmetric erosion network was revealed, which indicates a great work in the transfer of matter of first-order streams. First-order streams exceed those of the second and third orders streams in terms of catchment area, length and steepness of adjacent slopes. The interrelation of morphometric characteristics of different-order streams within third order sub-basins are most fully traced with the using of structural indices and their comparison with modal indicators. In general, the Ihe-Ukhgun river basin is characterized by a heterogeneous structure of the streams ratio of the first, second and third orders. The basins of the Khurguta, Khubyty and Ulan-Gol rivers have the highest degree of homogeneity. At the same time, for the Ihe-Ukhgun river basin, there is no direct relationship with the area of the third order drainage basins.