Updating the geomorphological zoning of the West Siberian Plain based on the AW3D30 DEM

Abstract

Geomorphological zoning is routinely used to properly organize the available data on the landform type and genesis in large areas. Most of the existing geomorphological zoning charts for the West Siberian Plain were developed back in the 1970s. They have significant drawbacks in terms of boundary position accuracy and accounting and lack the latest data and are hardly suitable for research purposes. This study updated the geomorphological region boundaries of the West Siberian Plain. We used the ALOS World 3D digital surface model (30 m resolution) and the existing charts by S. Voskresensky, M. Gorodetskaya, Yu. Mescheryakov, V. Nikolayev, G. Richter, V. Trofimov, and G.A. Lazukov. It was a combined approach with manual and automatic interpretation. The visual features are slope breaks, terrace ledges, and watersheds. We applied object-oriented segmentation with k-means clustering for automatic classification. As a result, the boundary of the West Siberian Plain was corrected (its area is 2.93 mln. km²). 74 geomorphological regions were found. The average region area is 39,600 km², and the average absolute elevation is 88.1 m. The region boundaries can be reproduced and verified with any detailed digital surface model provided that it is created by continuous instrumental measurements of the surface elevations. We also estimated the average morphometric indices for each region (average elevation, slope angle, total curvature, thalweg density, and the share of land covered by lakes). Generally, there is a sustainable trend: the landform uniformity of the West Siberian Plain increases from north to south while the share of lakes decreases. We assumed that the most probable cause of the geomorphological differences between the northern and southern parts is the impact of the blanket glaciations on the northern part of the plain.